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Date: Tue, 8 Aug 2023 20:54:51 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
torvalds@...ux-foundation.org, stable@...r.kernel.org
Cc: lwn@....net, jslaby@...e.cz,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: Linux 4.19.290
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index dee993602c31..a531b208902f 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -472,16 +472,17 @@ Description: information about CPUs heterogeneity.
cpu_capacity: capacity of cpu#.
What: /sys/devices/system/cpu/vulnerabilities
+ /sys/devices/system/cpu/vulnerabilities/gather_data_sampling
+ /sys/devices/system/cpu/vulnerabilities/itlb_multihit
+ /sys/devices/system/cpu/vulnerabilities/l1tf
+ /sys/devices/system/cpu/vulnerabilities/mds
/sys/devices/system/cpu/vulnerabilities/meltdown
+ /sys/devices/system/cpu/vulnerabilities/mmio_stale_data
+ /sys/devices/system/cpu/vulnerabilities/spec_store_bypass
/sys/devices/system/cpu/vulnerabilities/spectre_v1
/sys/devices/system/cpu/vulnerabilities/spectre_v2
- /sys/devices/system/cpu/vulnerabilities/spec_store_bypass
- /sys/devices/system/cpu/vulnerabilities/l1tf
- /sys/devices/system/cpu/vulnerabilities/mds
/sys/devices/system/cpu/vulnerabilities/srbds
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
- /sys/devices/system/cpu/vulnerabilities/itlb_multihit
- /sys/devices/system/cpu/vulnerabilities/mmio_stale_data
Date: January 2018
Contact: Linux kernel mailing list <linux-kernel@...r.kernel.org>
Description: Information about CPU vulnerabilities
diff --git a/Documentation/admin-guide/hw-vuln/gather_data_sampling.rst b/Documentation/admin-guide/hw-vuln/gather_data_sampling.rst
new file mode 100644
index 000000000000..264bfa937f7d
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/gather_data_sampling.rst
@@ -0,0 +1,109 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+GDS - Gather Data Sampling
+==========================
+
+Gather Data Sampling is a hardware vulnerability which allows unprivileged
+speculative access to data which was previously stored in vector registers.
+
+Problem
+-------
+When a gather instruction performs loads from memory, different data elements
+are merged into the destination vector register. However, when a gather
+instruction that is transiently executed encounters a fault, stale data from
+architectural or internal vector registers may get transiently forwarded to the
+destination vector register instead. This will allow a malicious attacker to
+infer stale data using typical side channel techniques like cache timing
+attacks. GDS is a purely sampling-based attack.
+
+The attacker uses gather instructions to infer the stale vector register data.
+The victim does not need to do anything special other than use the vector
+registers. The victim does not need to use gather instructions to be
+vulnerable.
+
+Because the buffers are shared between Hyper-Threads cross Hyper-Thread attacks
+are possible.
+
+Attack scenarios
+----------------
+Without mitigation, GDS can infer stale data across virtually all
+permission boundaries:
+
+ Non-enclaves can infer SGX enclave data
+ Userspace can infer kernel data
+ Guests can infer data from hosts
+ Guest can infer guest from other guests
+ Users can infer data from other users
+
+Because of this, it is important to ensure that the mitigation stays enabled in
+lower-privilege contexts like guests and when running outside SGX enclaves.
+
+The hardware enforces the mitigation for SGX. Likewise, VMMs should ensure
+that guests are not allowed to disable the GDS mitigation. If a host erred and
+allowed this, a guest could theoretically disable GDS mitigation, mount an
+attack, and re-enable it.
+
+Mitigation mechanism
+--------------------
+This issue is mitigated in microcode. The microcode defines the following new
+bits:
+
+ ================================ === ============================
+ IA32_ARCH_CAPABILITIES[GDS_CTRL] R/O Enumerates GDS vulnerability
+ and mitigation support.
+ IA32_ARCH_CAPABILITIES[GDS_NO] R/O Processor is not vulnerable.
+ IA32_MCU_OPT_CTRL[GDS_MITG_DIS] R/W Disables the mitigation
+ 0 by default.
+ IA32_MCU_OPT_CTRL[GDS_MITG_LOCK] R/W Locks GDS_MITG_DIS=0. Writes
+ to GDS_MITG_DIS are ignored
+ Can't be cleared once set.
+ ================================ === ============================
+
+GDS can also be mitigated on systems that don't have updated microcode by
+disabling AVX. This can be done by setting gather_data_sampling="force" or
+"clearcpuid=avx" on the kernel command-line.
+
+If used, these options will disable AVX use by turning off XSAVE YMM support.
+However, the processor will still enumerate AVX support. Userspace that
+does not follow proper AVX enumeration to check both AVX *and* XSAVE YMM
+support will break.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+The mitigation can be disabled by setting "gather_data_sampling=off" or
+"mitigations=off" on the kernel command line. Not specifying either will default
+to the mitigation being enabled. Specifying "gather_data_sampling=force" will
+use the microcode mitigation when available or disable AVX on affected systems
+where the microcode hasn't been updated to include the mitigation.
+
+GDS System Information
+------------------------
+The kernel provides vulnerability status information through sysfs. For
+GDS this can be accessed by the following sysfs file:
+
+/sys/devices/system/cpu/vulnerabilities/gather_data_sampling
+
+The possible values contained in this file are:
+
+ ============================== =============================================
+ Not affected Processor not vulnerable.
+ Vulnerable Processor vulnerable and mitigation disabled.
+ Vulnerable: No microcode Processor vulnerable and microcode is missing
+ mitigation.
+ Mitigation: AVX disabled,
+ no microcode Processor is vulnerable and microcode is missing
+ mitigation. AVX disabled as mitigation.
+ Mitigation: Microcode Processor is vulnerable and mitigation is in
+ effect.
+ Mitigation: Microcode (locked) Processor is vulnerable and mitigation is in
+ effect and cannot be disabled.
+ Unknown: Dependent on
+ hypervisor status Running on a virtual guest processor that is
+ affected but with no way to know if host
+ processor is mitigated or vulnerable.
+ ============================== =============================================
+
+GDS Default mitigation
+----------------------
+The updated microcode will enable the mitigation by default. The kernel's
+default action is to leave the mitigation enabled.
diff --git a/Documentation/admin-guide/hw-vuln/index.rst b/Documentation/admin-guide/hw-vuln/index.rst
index 2adec1e6520a..245468b0f2be 100644
--- a/Documentation/admin-guide/hw-vuln/index.rst
+++ b/Documentation/admin-guide/hw-vuln/index.rst
@@ -16,3 +16,4 @@ are configurable at compile, boot or run time.
multihit.rst
special-register-buffer-data-sampling.rst
processor_mmio_stale_data.rst
+ gather_data_sampling.rst
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 42ddd78ea001..84c34f7e8984 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1290,6 +1290,26 @@
Format: off | on
default: on
+ gather_data_sampling=
+ [X86,INTEL] Control the Gather Data Sampling (GDS)
+ mitigation.
+
+ Gather Data Sampling is a hardware vulnerability which
+ allows unprivileged speculative access to data which was
+ previously stored in vector registers.
+
+ This issue is mitigated by default in updated microcode.
+ The mitigation may have a performance impact but can be
+ disabled. On systems without the microcode mitigation
+ disabling AVX serves as a mitigation.
+
+ force: Disable AVX to mitigate systems without
+ microcode mitigation. No effect if the microcode
+ mitigation is present. Known to cause crashes in
+ userspace with buggy AVX enumeration.
+
+ off: Disable GDS mitigation.
+
gcov_persist= [GCOV] When non-zero (default), profiling data for
kernel modules is saved and remains accessible via
debugfs, even when the module is unloaded/reloaded.
@@ -2555,22 +2575,23 @@
Disable all optional CPU mitigations. This
improves system performance, but it may also
expose users to several CPU vulnerabilities.
- Equivalent to: nopti [X86,PPC]
+ Equivalent to: gather_data_sampling=off [X86]
kpti=0 [ARM64]
- nospectre_v1 [PPC]
+ kvm.nx_huge_pages=off [X86]
+ l1tf=off [X86]
+ mds=off [X86]
+ mmio_stale_data=off [X86]
+ no_entry_flush [PPC]
+ no_uaccess_flush [PPC]
nobp=0 [S390]
+ nopti [X86,PPC]
+ nospectre_v1 [PPC]
nospectre_v1 [X86]
nospectre_v2 [X86,PPC,S390,ARM64]
- spectre_v2_user=off [X86]
spec_store_bypass_disable=off [X86,PPC]
+ spectre_v2_user=off [X86]
ssbd=force-off [ARM64]
- l1tf=off [X86]
- mds=off [X86]
tsx_async_abort=off [X86]
- kvm.nx_huge_pages=off [X86]
- no_entry_flush [PPC]
- no_uaccess_flush [PPC]
- mmio_stale_data=off [X86]
Exceptions:
This does not have any effect on
diff --git a/Makefile b/Makefile
index 9af8ec084269..5cd8768fc083 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
VERSION = 4
PATCHLEVEL = 19
-SUBLEVEL = 289
+SUBLEVEL = 290
EXTRAVERSION =
NAME = "People's Front"
diff --git a/arch/Kconfig b/arch/Kconfig
index dd71b34fe4f5..6e77e795517d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -249,6 +249,9 @@ config ARCH_HAS_FORTIFY_SOURCE
config ARCH_HAS_SET_MEMORY
bool
+config ARCH_HAS_CPU_FINALIZE_INIT
+ bool
+
# Select if arch init_task must go in the __init_task_data section
config ARCH_TASK_STRUCT_ON_STACK
bool
diff --git a/arch/alpha/include/asm/bugs.h b/arch/alpha/include/asm/bugs.h
deleted file mode 100644
index 78030d1c7e7e..000000000000
--- a/arch/alpha/include/asm/bugs.h
+++ /dev/null
@@ -1,20 +0,0 @@
-/*
- * include/asm-alpha/bugs.h
- *
- * Copyright (C) 1994 Linus Torvalds
- */
-
-/*
- * This is included by init/main.c to check for architecture-dependent bugs.
- *
- * Needs:
- * void check_bugs(void);
- */
-
-/*
- * I don't know of any alpha bugs yet.. Nice chip
- */
-
-static void check_bugs(void)
-{
-}
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 41bde0e62e90..9b075719a7d9 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -4,6 +4,7 @@ config ARM
default y
select ARCH_CLOCKSOURCE_DATA
select ARCH_DISCARD_MEMBLOCK if !HAVE_ARCH_PFN_VALID && !KEXEC
+ select ARCH_HAS_CPU_FINALIZE_INIT if MMU
select ARCH_HAS_DEBUG_VIRTUAL if MMU
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_ELF_RANDOMIZE
diff --git a/arch/arm/include/asm/bugs.h b/arch/arm/include/asm/bugs.h
index 73a99c72a930..21b6f742b3ba 100644
--- a/arch/arm/include/asm/bugs.h
+++ b/arch/arm/include/asm/bugs.h
@@ -1,6 +1,4 @@
/*
- * arch/arm/include/asm/bugs.h
- *
* Copyright (C) 1995-2003 Russell King
*
* This program is free software; you can redistribute it and/or modify
@@ -13,10 +11,8 @@
extern void check_writebuffer_bugs(void);
#ifdef CONFIG_MMU
-extern void check_bugs(void);
extern void check_other_bugs(void);
#else
-#define check_bugs() do { } while (0)
#define check_other_bugs() do { } while (0)
#endif
diff --git a/arch/arm/kernel/bugs.c b/arch/arm/kernel/bugs.c
index d41d3598e5e5..e9fc25350784 100644
--- a/arch/arm/kernel/bugs.c
+++ b/arch/arm/kernel/bugs.c
@@ -1,5 +1,6 @@
// SPDX-Identifier: GPL-2.0
#include <linux/init.h>
+#include <linux/cpu.h>
#include <asm/bugs.h>
#include <asm/proc-fns.h>
@@ -11,7 +12,7 @@ void check_other_bugs(void)
#endif
}
-void __init check_bugs(void)
+void __init arch_cpu_finalize_init(void)
{
check_writebuffer_bugs();
check_other_bugs();
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 0d56b19b7511..58f63446c657 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -8,6 +8,7 @@ menu "Processor type and features"
config IA64
bool
+ select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select PCI if (!IA64_HP_SIM)
diff --git a/arch/ia64/include/asm/bugs.h b/arch/ia64/include/asm/bugs.h
deleted file mode 100644
index 0d6b9bded56c..000000000000
--- a/arch/ia64/include/asm/bugs.h
+++ /dev/null
@@ -1,20 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * This is included by init/main.c to check for architecture-dependent bugs.
- *
- * Needs:
- * void check_bugs(void);
- *
- * Based on <asm-alpha/bugs.h>.
- *
- * Modified 1998, 1999, 2003
- * David Mosberger-Tang <davidm@....hp.com>, Hewlett-Packard Co.
- */
-#ifndef _ASM_IA64_BUGS_H
-#define _ASM_IA64_BUGS_H
-
-#include <asm/processor.h>
-
-extern void check_bugs (void);
-
-#endif /* _ASM_IA64_BUGS_H */
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 0e6c2d9fb498..41af687bc1dc 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -1050,8 +1050,7 @@ cpu_init (void)
platform_cpu_init();
}
-void __init
-check_bugs (void)
+void __init arch_cpu_finalize_init(void)
{
ia64_patch_mckinley_e9((unsigned long) __start___mckinley_e9_bundles,
(unsigned long) __end___mckinley_e9_bundles);
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 070553791e97..05b7e4cbb16e 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -2,6 +2,7 @@
config M68K
bool
default y
+ select ARCH_HAS_CPU_FINALIZE_INIT if MMU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA
select ARCH_MIGHT_HAVE_PC_PARPORT if ISA
select ARCH_NO_COHERENT_DMA_MMAP if !MMU
diff --git a/arch/m68k/include/asm/bugs.h b/arch/m68k/include/asm/bugs.h
deleted file mode 100644
index 745530651e0b..000000000000
--- a/arch/m68k/include/asm/bugs.h
+++ /dev/null
@@ -1,21 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * include/asm-m68k/bugs.h
- *
- * Copyright (C) 1994 Linus Torvalds
- */
-
-/*
- * This is included by init/main.c to check for architecture-dependent bugs.
- *
- * Needs:
- * void check_bugs(void);
- */
-
-#ifdef CONFIG_MMU
-extern void check_bugs(void); /* in arch/m68k/kernel/setup.c */
-#else
-static void check_bugs(void)
-{
-}
-#endif
diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
index de44899c0e61..461e14f46cfe 100644
--- a/arch/m68k/kernel/setup_mm.c
+++ b/arch/m68k/kernel/setup_mm.c
@@ -10,6 +10,7 @@
*/
#include <linux/kernel.h>
+#include <linux/cpu.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/delay.h>
@@ -526,7 +527,7 @@ static int __init proc_hardware_init(void)
module_init(proc_hardware_init);
#endif
-void check_bugs(void)
+void __init arch_cpu_finalize_init(void)
{
#if defined(CONFIG_FPU) && !defined(CONFIG_M68KFPU_EMU)
if (m68k_fputype == 0) {
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 8a227a80f6bd..8d1d065aac35 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -4,6 +4,7 @@ config MIPS
default y
select ARCH_BINFMT_ELF_STATE
select ARCH_CLOCKSOURCE_DATA
+ select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_DISCARD_MEMBLOCK
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
diff --git a/arch/mips/include/asm/bugs.h b/arch/mips/include/asm/bugs.h
index d8ab8b7129b5..6d04d7d3a8f2 100644
--- a/arch/mips/include/asm/bugs.h
+++ b/arch/mips/include/asm/bugs.h
@@ -1,17 +1,11 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
- * This is included by init/main.c to check for architecture-dependent bugs.
- *
* Copyright (C) 2007 Maciej W. Rozycki
- *
- * Needs:
- * void check_bugs(void);
*/
#ifndef _ASM_BUGS_H
#define _ASM_BUGS_H
#include <linux/bug.h>
-#include <linux/delay.h>
#include <linux/smp.h>
#include <asm/cpu.h>
@@ -31,17 +25,6 @@ static inline void check_bugs_early(void)
#endif
}
-static inline void check_bugs(void)
-{
- unsigned int cpu = smp_processor_id();
-
- cpu_data[cpu].udelay_val = loops_per_jiffy;
- check_bugs32();
-#ifdef CONFIG_64BIT
- check_bugs64();
-#endif
-}
-
static inline int r4k_daddiu_bug(void)
{
#ifdef CONFIG_64BIT
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 124bc842306d..b424f5e84487 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -11,6 +11,8 @@
* Copyright (C) 2000, 2001, 2002, 2007 Maciej W. Rozycki
*/
#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/export.h>
#include <linux/screen_info.h>
@@ -1108,3 +1110,14 @@ static int __init setnocoherentio(char *str)
}
early_param("nocoherentio", setnocoherentio);
#endif
+
+void __init arch_cpu_finalize_init(void)
+{
+ unsigned int cpu = smp_processor_id();
+
+ cpu_data[cpu].udelay_val = loops_per_jiffy;
+ check_bugs32();
+
+ if (IS_ENABLED(CONFIG_CPU_R4X00_BUGS64))
+ check_bugs64();
+}
diff --git a/arch/parisc/include/asm/bugs.h b/arch/parisc/include/asm/bugs.h
deleted file mode 100644
index 0a7f9db6bd1c..000000000000
--- a/arch/parisc/include/asm/bugs.h
+++ /dev/null
@@ -1,20 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * include/asm-parisc/bugs.h
- *
- * Copyright (C) 1999 Mike Shaver
- */
-
-/*
- * This is included by init/main.c to check for architecture-dependent bugs.
- *
- * Needs:
- * void check_bugs(void);
- */
-
-#include <asm/processor.h>
-
-static inline void check_bugs(void)
-{
-// identify_cpu(&boot_cpu_data);
-}
diff --git a/arch/powerpc/include/asm/bugs.h b/arch/powerpc/include/asm/bugs.h
deleted file mode 100644
index 42fdb73e3068..000000000000
--- a/arch/powerpc/include/asm/bugs.h
+++ /dev/null
@@ -1,18 +0,0 @@
-#ifndef _ASM_POWERPC_BUGS_H
-#define _ASM_POWERPC_BUGS_H
-
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-/*
- * This file is included by 'init/main.c' to check for
- * architecture-dependent bugs.
- */
-
-static inline void check_bugs(void) { }
-
-#endif /* _ASM_POWERPC_BUGS_H */
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 1fb7b6d72baf..63e00320eb3c 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
config SUPERH
def_bool y
+ select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_MIGHT_HAVE_PC_PARPORT
diff --git a/arch/sh/include/asm/bugs.h b/arch/sh/include/asm/bugs.h
deleted file mode 100644
index 030df56bfdb2..000000000000
--- a/arch/sh/include/asm/bugs.h
+++ /dev/null
@@ -1,78 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __ASM_SH_BUGS_H
-#define __ASM_SH_BUGS_H
-
-/*
- * This is included by init/main.c to check for architecture-dependent bugs.
- *
- * Needs:
- * void check_bugs(void);
- */
-
-/*
- * I don't know of any Super-H bugs yet.
- */
-
-#include <asm/processor.h>
-
-extern void select_idle_routine(void);
-
-static void __init check_bugs(void)
-{
- extern unsigned long loops_per_jiffy;
- char *p = &init_utsname()->machine[2]; /* "sh" */
-
- select_idle_routine();
-
- current_cpu_data.loops_per_jiffy = loops_per_jiffy;
-
- switch (current_cpu_data.family) {
- case CPU_FAMILY_SH2:
- *p++ = '2';
- break;
- case CPU_FAMILY_SH2A:
- *p++ = '2';
- *p++ = 'a';
- break;
- case CPU_FAMILY_SH3:
- *p++ = '3';
- break;
- case CPU_FAMILY_SH4:
- *p++ = '4';
- break;
- case CPU_FAMILY_SH4A:
- *p++ = '4';
- *p++ = 'a';
- break;
- case CPU_FAMILY_SH4AL_DSP:
- *p++ = '4';
- *p++ = 'a';
- *p++ = 'l';
- *p++ = '-';
- *p++ = 'd';
- *p++ = 's';
- *p++ = 'p';
- break;
- case CPU_FAMILY_SH5:
- *p++ = '6';
- *p++ = '4';
- break;
- case CPU_FAMILY_UNKNOWN:
- /*
- * Specifically use CPU_FAMILY_UNKNOWN rather than
- * default:, so we're able to have the compiler whine
- * about unhandled enumerations.
- */
- break;
- }
-
- printk("CPU: %s\n", get_cpu_subtype(¤t_cpu_data));
-
-#ifndef __LITTLE_ENDIAN__
- /* 'eb' means 'Endian Big' */
- *p++ = 'e';
- *p++ = 'b';
-#endif
- *p = '\0';
-}
-#endif /* __ASM_SH_BUGS_H */
diff --git a/arch/sh/include/asm/processor.h b/arch/sh/include/asm/processor.h
index 6fbf8c80e498..386786b1594a 100644
--- a/arch/sh/include/asm/processor.h
+++ b/arch/sh/include/asm/processor.h
@@ -173,6 +173,8 @@ extern unsigned int instruction_size(unsigned int insn);
#define instruction_size(insn) (4)
#endif
+void select_idle_routine(void);
+
#endif /* __ASSEMBLY__ */
#ifdef CONFIG_SUPERH32
diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index be616ee0cf87..5169309fdf98 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -18,6 +18,7 @@
#include <linux/smp.h>
#include <linux/atomic.h>
#include <asm/pgalloc.h>
+#include <asm/processor.h>
#include <asm/smp.h>
#include <asm/bl_bit.h>
diff --git a/arch/sh/kernel/setup.c b/arch/sh/kernel/setup.c
index b2f44eb7ce19..8ef497062350 100644
--- a/arch/sh/kernel/setup.c
+++ b/arch/sh/kernel/setup.c
@@ -42,6 +42,7 @@
#include <asm/smp.h>
#include <asm/mmu_context.h>
#include <asm/mmzone.h>
+#include <asm/processor.h>
#include <asm/sparsemem.h>
/*
@@ -361,3 +362,57 @@ int test_mode_pin(int pin)
{
return sh_mv.mv_mode_pins() & pin;
}
+
+void __init arch_cpu_finalize_init(void)
+{
+ char *p = &init_utsname()->machine[2]; /* "sh" */
+
+ select_idle_routine();
+
+ current_cpu_data.loops_per_jiffy = loops_per_jiffy;
+
+ switch (current_cpu_data.family) {
+ case CPU_FAMILY_SH2:
+ *p++ = '2';
+ break;
+ case CPU_FAMILY_SH2A:
+ *p++ = '2';
+ *p++ = 'a';
+ break;
+ case CPU_FAMILY_SH3:
+ *p++ = '3';
+ break;
+ case CPU_FAMILY_SH4:
+ *p++ = '4';
+ break;
+ case CPU_FAMILY_SH4A:
+ *p++ = '4';
+ *p++ = 'a';
+ break;
+ case CPU_FAMILY_SH4AL_DSP:
+ *p++ = '4';
+ *p++ = 'a';
+ *p++ = 'l';
+ *p++ = '-';
+ *p++ = 'd';
+ *p++ = 's';
+ *p++ = 'p';
+ break;
+ case CPU_FAMILY_UNKNOWN:
+ /*
+ * Specifically use CPU_FAMILY_UNKNOWN rather than
+ * default:, so we're able to have the compiler whine
+ * about unhandled enumerations.
+ */
+ break;
+ }
+
+ pr_info("CPU: %s\n", get_cpu_subtype(¤t_cpu_data));
+
+#ifndef __LITTLE_ENDIAN__
+ /* 'eb' means 'Endian Big' */
+ *p++ = 'e';
+ *p++ = 'b';
+#endif
+ *p = '\0';
+}
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 426accab2a88..e231779928dd 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -12,6 +12,7 @@ config 64BIT
config SPARC
bool
default y
+ select ARCH_HAS_CPU_FINALIZE_INIT if !SMP
select ARCH_MIGHT_HAVE_PC_PARPORT if SPARC64 && PCI
select ARCH_MIGHT_HAVE_PC_SERIO
select OF
diff --git a/arch/sparc/include/asm/bugs.h b/arch/sparc/include/asm/bugs.h
deleted file mode 100644
index 02fa369b9c21..000000000000
--- a/arch/sparc/include/asm/bugs.h
+++ /dev/null
@@ -1,18 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/* include/asm/bugs.h: Sparc probes for various bugs.
- *
- * Copyright (C) 1996, 2007 David S. Miller (davem@...emloft.net)
- */
-
-#ifdef CONFIG_SPARC32
-#include <asm/cpudata.h>
-#endif
-
-extern unsigned long loops_per_jiffy;
-
-static void __init check_bugs(void)
-{
-#if defined(CONFIG_SPARC32) && !defined(CONFIG_SMP)
- cpu_data(0).udelay_val = loops_per_jiffy;
-#endif
-}
diff --git a/arch/sparc/kernel/setup_32.c b/arch/sparc/kernel/setup_32.c
index 13664c377196..3ee6609e6eb5 100644
--- a/arch/sparc/kernel/setup_32.c
+++ b/arch/sparc/kernel/setup_32.c
@@ -422,3 +422,10 @@ static int __init topology_init(void)
}
subsys_initcall(topology_init);
+
+#if defined(CONFIG_SPARC32) && !defined(CONFIG_SMP)
+void __init arch_cpu_finalize_init(void)
+{
+ cpu_data(0).udelay_val = loops_per_jiffy;
+}
+#endif
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 6b9938919f0b..8f0cb2809939 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -5,6 +5,7 @@ menu "UML-specific options"
config UML
bool
default y
+ select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_HAS_KCOV
select ARCH_NO_PREEMPT
select HAVE_ARCH_AUDITSYSCALL
diff --git a/arch/um/include/asm/bugs.h b/arch/um/include/asm/bugs.h
deleted file mode 100644
index 4473942a0839..000000000000
--- a/arch/um/include/asm/bugs.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __UM_BUGS_H
-#define __UM_BUGS_H
-
-void check_bugs(void);
-
-#endif
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index c23f8857a798..66390c321155 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -3,6 +3,7 @@
* Licensed under the GPL
*/
+#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/mm.h>
@@ -352,7 +353,7 @@ void __init setup_arch(char **cmdline_p)
setup_hostinfo(host_info, sizeof host_info);
}
-void __init check_bugs(void)
+void __init arch_cpu_finalize_init(void)
{
arch_check_bugs();
os_check_bugs();
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index be4403a8e1b4..9fd2e3c2494a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -50,6 +50,7 @@ config X86
select ARCH_CLOCKSOURCE_DATA
select ARCH_DISCARD_MEMBLOCK
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
+ select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_ELF_RANDOMIZE
@@ -2437,6 +2438,25 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
def_bool y
depends on X86_64 || X86_PAE
+config GDS_FORCE_MITIGATION
+ bool "Force GDS Mitigation"
+ depends on CPU_SUP_INTEL
+ default n
+ help
+ Gather Data Sampling (GDS) is a hardware vulnerability which allows
+ unprivileged speculative access to data which was previously stored in
+ vector registers.
+
+ This option is equivalent to setting gather_data_sampling=force on the
+ command line. The microcode mitigation is used if present, otherwise
+ AVX is disabled as a mitigation. On affected systems that are missing
+ the microcode any userspace code that unconditionally uses AVX will
+ break with this option set.
+
+ Setting this option on systems not vulnerable to GDS has no effect.
+
+ If in doubt, say N.
+
config ARCH_ENABLE_HUGEPAGE_MIGRATION
def_bool y
depends on X86_64 && HUGETLB_PAGE && MIGRATION
diff --git a/arch/x86/include/asm/bugs.h b/arch/x86/include/asm/bugs.h
index 542509b53e0f..dd8ff1ca2aef 100644
--- a/arch/x86/include/asm/bugs.h
+++ b/arch/x86/include/asm/bugs.h
@@ -4,8 +4,6 @@
#include <asm/processor.h>
-extern void check_bugs(void);
-
#if defined(CONFIG_CPU_SUP_INTEL)
void check_mpx_erratum(struct cpuinfo_x86 *c);
#else
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index bd4374f56651..5cf8dca571cf 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -409,5 +409,6 @@
#define X86_BUG_MMIO_UNKNOWN X86_BUG(26) /* CPU is too old and its MMIO Stale Data status is unknown */
#define X86_BUG_RETBLEED X86_BUG(27) /* CPU is affected by RETBleed */
#define X86_BUG_EIBRS_PBRSB X86_BUG(28) /* EIBRS is vulnerable to Post Barrier RSB Predictions */
+#define X86_BUG_GDS X86_BUG(29) /* CPU is affected by Gather Data Sampling */
#endif /* _ASM_X86_CPUFEATURES_H */
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 4f274d851986..51dc8201b51e 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -42,7 +42,7 @@ extern int dump_fpu(struct pt_regs *ptregs, struct user_i387_struct *fpstate);
extern void fpu__init_cpu(void);
extern void fpu__init_system_xstate(void);
extern void fpu__init_cpu_xstate(void);
-extern void fpu__init_system(struct cpuinfo_x86 *c);
+extern void fpu__init_system(void);
extern void fpu__init_check_bugs(void);
extern void fpu__resume_cpu(void);
extern u64 fpu__get_supported_xfeatures_mask(void);
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 616f8e637bc3..b51ac6eed904 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -80,6 +80,8 @@ early_set_memory_decrypted(unsigned long vaddr, unsigned long size) { return 0;
static inline int __init
early_set_memory_encrypted(unsigned long vaddr, unsigned long size) { return 0; }
+static inline void mem_encrypt_init(void) { }
+
#define __bss_decrypted
#endif /* CONFIG_AMD_MEM_ENCRYPT */
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index d9c6603dcd63..efedd16231ff 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -138,6 +138,15 @@
* Not susceptible to Post-Barrier
* Return Stack Buffer Predictions.
*/
+#define ARCH_CAP_GDS_CTRL BIT(25) /*
+ * CPU is vulnerable to Gather
+ * Data Sampling (GDS) and
+ * has controls for mitigation.
+ */
+#define ARCH_CAP_GDS_NO BIT(26) /*
+ * CPU is not vulnerable to Gather
+ * Data Sampling (GDS).
+ */
#define MSR_IA32_FLUSH_CMD 0x0000010b
#define L1D_FLUSH BIT(0) /*
@@ -156,6 +165,8 @@
#define MSR_IA32_MCU_OPT_CTRL 0x00000123
#define RNGDS_MITG_DIS BIT(0)
#define FB_CLEAR_DIS BIT(3) /* CPU Fill buffer clear disable */
+#define GDS_MITG_DIS BIT(4) /* Disable GDS mitigation */
+#define GDS_MITG_LOCKED BIT(5) /* GDS mitigation locked */
#define MSR_IA32_SYSENTER_CS 0x00000174
#define MSR_IA32_SYSENTER_ESP 0x00000175
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 680fa070e18b..6e1acbdd27a5 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -9,7 +9,6 @@
* - Andrew D. Balsa (code cleanup).
*/
#include <linux/init.h>
-#include <linux/utsname.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/nospec.h>
@@ -25,9 +24,7 @@
#include <asm/msr.h>
#include <asm/vmx.h>
#include <asm/paravirt.h>
-#include <asm/alternative.h>
#include <asm/pgtable.h>
-#include <asm/set_memory.h>
#include <asm/intel-family.h>
#include <asm/e820/api.h>
#include <asm/hypervisor.h>
@@ -47,6 +44,7 @@ static void __init md_clear_select_mitigation(void);
static void __init taa_select_mitigation(void);
static void __init mmio_select_mitigation(void);
static void __init srbds_select_mitigation(void);
+static void __init gds_select_mitigation(void);
/* The base value of the SPEC_CTRL MSR without task-specific bits set */
u64 x86_spec_ctrl_base;
@@ -115,21 +113,8 @@ EXPORT_SYMBOL_GPL(mds_idle_clear);
DEFINE_STATIC_KEY_FALSE(mmio_stale_data_clear);
EXPORT_SYMBOL_GPL(mmio_stale_data_clear);
-void __init check_bugs(void)
+void __init cpu_select_mitigations(void)
{
- identify_boot_cpu();
-
- /*
- * identify_boot_cpu() initialized SMT support information, let the
- * core code know.
- */
- cpu_smt_check_topology();
-
- if (!IS_ENABLED(CONFIG_SMP)) {
- pr_info("CPU: ");
- print_cpu_info(&boot_cpu_data);
- }
-
/*
* Read the SPEC_CTRL MSR to account for reserved bits which may
* have unknown values. AMD64_LS_CFG MSR is cached in the early AMD
@@ -165,39 +150,7 @@ void __init check_bugs(void)
l1tf_select_mitigation();
md_clear_select_mitigation();
srbds_select_mitigation();
-
- arch_smt_update();
-
-#ifdef CONFIG_X86_32
- /*
- * Check whether we are able to run this kernel safely on SMP.
- *
- * - i386 is no longer supported.
- * - In order to run on anything without a TSC, we need to be
- * compiled for a i486.
- */
- if (boot_cpu_data.x86 < 4)
- panic("Kernel requires i486+ for 'invlpg' and other features");
-
- init_utsname()->machine[1] =
- '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
- alternative_instructions();
-
- fpu__init_check_bugs();
-#else /* CONFIG_X86_64 */
- alternative_instructions();
-
- /*
- * Make sure the first 2MB area is not mapped by huge pages
- * There are typically fixed size MTRRs in there and overlapping
- * MTRRs into large pages causes slow downs.
- *
- * Right now we don't do that with gbpages because there seems
- * very little benefit for that case.
- */
- if (!direct_gbpages)
- set_memory_4k((unsigned long)__va(0), 1);
-#endif
+ gds_select_mitigation();
}
/*
@@ -648,6 +601,149 @@ static int __init srbds_parse_cmdline(char *str)
}
early_param("srbds", srbds_parse_cmdline);
+#undef pr_fmt
+#define pr_fmt(fmt) "GDS: " fmt
+
+enum gds_mitigations {
+ GDS_MITIGATION_OFF,
+ GDS_MITIGATION_UCODE_NEEDED,
+ GDS_MITIGATION_FORCE,
+ GDS_MITIGATION_FULL,
+ GDS_MITIGATION_FULL_LOCKED,
+ GDS_MITIGATION_HYPERVISOR,
+};
+
+#if IS_ENABLED(CONFIG_GDS_FORCE_MITIGATION)
+static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FORCE;
+#else
+static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FULL;
+#endif
+
+static const char * const gds_strings[] = {
+ [GDS_MITIGATION_OFF] = "Vulnerable",
+ [GDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode",
+ [GDS_MITIGATION_FORCE] = "Mitigation: AVX disabled, no microcode",
+ [GDS_MITIGATION_FULL] = "Mitigation: Microcode",
+ [GDS_MITIGATION_FULL_LOCKED] = "Mitigation: Microcode (locked)",
+ [GDS_MITIGATION_HYPERVISOR] = "Unknown: Dependent on hypervisor status",
+};
+
+bool gds_ucode_mitigated(void)
+{
+ return (gds_mitigation == GDS_MITIGATION_FULL ||
+ gds_mitigation == GDS_MITIGATION_FULL_LOCKED);
+}
+EXPORT_SYMBOL_GPL(gds_ucode_mitigated);
+
+void update_gds_msr(void)
+{
+ u64 mcu_ctrl_after;
+ u64 mcu_ctrl;
+
+ switch (gds_mitigation) {
+ case GDS_MITIGATION_OFF:
+ rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
+ mcu_ctrl |= GDS_MITG_DIS;
+ break;
+ case GDS_MITIGATION_FULL_LOCKED:
+ /*
+ * The LOCKED state comes from the boot CPU. APs might not have
+ * the same state. Make sure the mitigation is enabled on all
+ * CPUs.
+ */
+ case GDS_MITIGATION_FULL:
+ rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
+ mcu_ctrl &= ~GDS_MITG_DIS;
+ break;
+ case GDS_MITIGATION_FORCE:
+ case GDS_MITIGATION_UCODE_NEEDED:
+ case GDS_MITIGATION_HYPERVISOR:
+ return;
+ };
+
+ wrmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
+
+ /*
+ * Check to make sure that the WRMSR value was not ignored. Writes to
+ * GDS_MITG_DIS will be ignored if this processor is locked but the boot
+ * processor was not.
+ */
+ rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl_after);
+ WARN_ON_ONCE(mcu_ctrl != mcu_ctrl_after);
+}
+
+static void __init gds_select_mitigation(void)
+{
+ u64 mcu_ctrl;
+
+ if (!boot_cpu_has_bug(X86_BUG_GDS))
+ return;
+
+ if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
+ gds_mitigation = GDS_MITIGATION_HYPERVISOR;
+ goto out;
+ }
+
+ if (cpu_mitigations_off())
+ gds_mitigation = GDS_MITIGATION_OFF;
+ /* Will verify below that mitigation _can_ be disabled */
+
+ /* No microcode */
+ if (!(x86_read_arch_cap_msr() & ARCH_CAP_GDS_CTRL)) {
+ if (gds_mitigation == GDS_MITIGATION_FORCE) {
+ /*
+ * This only needs to be done on the boot CPU so do it
+ * here rather than in update_gds_msr()
+ */
+ setup_clear_cpu_cap(X86_FEATURE_AVX);
+ pr_warn("Microcode update needed! Disabling AVX as mitigation.\n");
+ } else {
+ gds_mitigation = GDS_MITIGATION_UCODE_NEEDED;
+ }
+ goto out;
+ }
+
+ /* Microcode has mitigation, use it */
+ if (gds_mitigation == GDS_MITIGATION_FORCE)
+ gds_mitigation = GDS_MITIGATION_FULL;
+
+ rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
+ if (mcu_ctrl & GDS_MITG_LOCKED) {
+ if (gds_mitigation == GDS_MITIGATION_OFF)
+ pr_warn("Mitigation locked. Disable failed.\n");
+
+ /*
+ * The mitigation is selected from the boot CPU. All other CPUs
+ * _should_ have the same state. If the boot CPU isn't locked
+ * but others are then update_gds_msr() will WARN() of the state
+ * mismatch. If the boot CPU is locked update_gds_msr() will
+ * ensure the other CPUs have the mitigation enabled.
+ */
+ gds_mitigation = GDS_MITIGATION_FULL_LOCKED;
+ }
+
+ update_gds_msr();
+out:
+ pr_info("%s\n", gds_strings[gds_mitigation]);
+}
+
+static int __init gds_parse_cmdline(char *str)
+{
+ if (!str)
+ return -EINVAL;
+
+ if (!boot_cpu_has_bug(X86_BUG_GDS))
+ return 0;
+
+ if (!strcmp(str, "off"))
+ gds_mitigation = GDS_MITIGATION_OFF;
+ else if (!strcmp(str, "force"))
+ gds_mitigation = GDS_MITIGATION_FORCE;
+
+ return 0;
+}
+early_param("gather_data_sampling", gds_parse_cmdline);
+
#undef pr_fmt
#define pr_fmt(fmt) "Spectre V1 : " fmt
@@ -2196,6 +2292,11 @@ static ssize_t retbleed_show_state(char *buf)
return sprintf(buf, "%s\n", retbleed_strings[retbleed_mitigation]);
}
+static ssize_t gds_show_state(char *buf)
+{
+ return sysfs_emit(buf, "%s\n", gds_strings[gds_mitigation]);
+}
+
static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
char *buf, unsigned int bug)
{
@@ -2245,6 +2346,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
case X86_BUG_RETBLEED:
return retbleed_show_state(buf);
+ case X86_BUG_GDS:
+ return gds_show_state(buf);
+
default:
break;
}
@@ -2309,4 +2413,9 @@ ssize_t cpu_show_retbleed(struct device *dev, struct device_attribute *attr, cha
{
return cpu_show_common(dev, attr, buf, X86_BUG_RETBLEED);
}
+
+ssize_t cpu_show_gds(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return cpu_show_common(dev, attr, buf, X86_BUG_GDS);
+}
#endif
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index ec324be00603..d315e928b95c 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -13,14 +13,20 @@
#include <linux/sched/mm.h>
#include <linux/sched/clock.h>
#include <linux/sched/task.h>
+#include <linux/sched/smt.h>
#include <linux/init.h>
#include <linux/kprobes.h>
#include <linux/kgdb.h>
+#include <linux/mem_encrypt.h>
#include <linux/smp.h>
+#include <linux/cpu.h>
#include <linux/io.h>
#include <linux/syscore_ops.h>
#include <asm/stackprotector.h>
+#include <linux/utsname.h>
+
+#include <asm/alternative.h>
#include <asm/perf_event.h>
#include <asm/mmu_context.h>
#include <asm/archrandom.h>
@@ -56,6 +62,7 @@
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/uv/uv.h>
#endif
+#include <asm/set_memory.h>
#include "cpu.h"
@@ -1040,6 +1047,12 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
#define MMIO_SBDS BIT(2)
/* CPU is affected by RETbleed, speculating where you would not expect it */
#define RETBLEED BIT(3)
+/* CPU is affected by SMT (cross-thread) return predictions */
+#define SMT_RSB BIT(4)
+/* CPU is affected by SRSO */
+#define SRSO BIT(5)
+/* CPU is affected by GDS */
+#define GDS BIT(6)
static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
VULNBL_INTEL_STEPPINGS(IVYBRIDGE, X86_STEPPING_ANY, SRBDS),
@@ -1052,18 +1065,20 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
VULNBL_INTEL_STEPPINGS(BROADWELL_X, X86_STEPPING_ANY, MMIO),
VULNBL_INTEL_STEPPINGS(BROADWELL_CORE, X86_STEPPING_ANY, SRBDS),
VULNBL_INTEL_STEPPINGS(SKYLAKE_MOBILE, X86_STEPPING_ANY, SRBDS | MMIO | RETBLEED),
- VULNBL_INTEL_STEPPINGS(SKYLAKE_X, X86_STEPPING_ANY, MMIO | RETBLEED),
+ VULNBL_INTEL_STEPPINGS(SKYLAKE_X, X86_STEPPING_ANY, MMIO | RETBLEED | GDS),
VULNBL_INTEL_STEPPINGS(SKYLAKE_DESKTOP, X86_STEPPING_ANY, SRBDS | MMIO | RETBLEED),
- VULNBL_INTEL_STEPPINGS(KABYLAKE_MOBILE, X86_STEPPING_ANY, SRBDS | MMIO | RETBLEED),
- VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPING_ANY, SRBDS | MMIO | RETBLEED),
+ VULNBL_INTEL_STEPPINGS(KABYLAKE_MOBILE, X86_STEPPING_ANY, SRBDS | MMIO | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPING_ANY, SRBDS | MMIO | RETBLEED | GDS),
VULNBL_INTEL_STEPPINGS(CANNONLAKE_MOBILE,X86_STEPPING_ANY, RETBLEED),
- VULNBL_INTEL_STEPPINGS(ICELAKE_MOBILE, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED),
- VULNBL_INTEL_STEPPINGS(ICELAKE_XEON_D, X86_STEPPING_ANY, MMIO),
- VULNBL_INTEL_STEPPINGS(ICELAKE_X, X86_STEPPING_ANY, MMIO),
- VULNBL_INTEL_STEPPINGS(COMETLAKE, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED),
- VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED),
+ VULNBL_INTEL_STEPPINGS(ICELAKE_MOBILE, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(ICELAKE_XEON_D, X86_STEPPING_ANY, MMIO | GDS),
+ VULNBL_INTEL_STEPPINGS(ICELAKE_X, X86_STEPPING_ANY, MMIO | GDS),
+ VULNBL_INTEL_STEPPINGS(COMETLAKE, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(TIGERLAKE_L, X86_STEPPING_ANY, GDS),
+ VULNBL_INTEL_STEPPINGS(TIGERLAKE, X86_STEPPING_ANY, GDS),
VULNBL_INTEL_STEPPINGS(LAKEFIELD, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED),
- VULNBL_INTEL_STEPPINGS(ROCKETLAKE, X86_STEPPING_ANY, MMIO | RETBLEED),
+ VULNBL_INTEL_STEPPINGS(ROCKETLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT, X86_STEPPING_ANY, MMIO | MMIO_SBDS),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_X, X86_STEPPING_ANY, MMIO),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS),
@@ -1186,6 +1201,16 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
!(ia32_cap & ARCH_CAP_PBRSB_NO))
setup_force_cpu_bug(X86_BUG_EIBRS_PBRSB);
+ /*
+ * Check if CPU is vulnerable to GDS. If running in a virtual machine on
+ * an affected processor, the VMM may have disabled the use of GATHER by
+ * disabling AVX2. The only way to do this in HW is to clear XCR0[2],
+ * which means that AVX will be disabled.
+ */
+ if (cpu_matches(cpu_vuln_blacklist, GDS) && !(ia32_cap & ARCH_CAP_GDS_NO) &&
+ boot_cpu_has(X86_FEATURE_AVX))
+ setup_force_cpu_bug(X86_BUG_GDS);
+
if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN))
return;
@@ -1271,8 +1296,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
cpu_set_bug_bits(c);
- fpu__init_system(c);
-
#ifdef CONFIG_X86_32
/*
* Regardless of whether PCID is enumerated, the SDM says
@@ -1661,6 +1684,8 @@ void identify_secondary_cpu(struct cpuinfo_x86 *c)
validate_apic_and_package_id(c);
x86_spec_ctrl_setup_ap();
update_srbds_msr();
+ if (boot_cpu_has_bug(X86_BUG_GDS))
+ update_gds_msr();
}
static __init int setup_noclflush(char *arg)
@@ -1978,8 +2003,6 @@ void cpu_init(void)
clear_all_debug_regs();
dbg_restore_debug_regs();
- fpu__init_cpu();
-
if (is_uv_system())
uv_cpu_init();
@@ -2043,8 +2066,6 @@ void cpu_init(void)
clear_all_debug_regs();
dbg_restore_debug_regs();
- fpu__init_cpu();
-
load_fixmap_gdt(cpu);
}
#endif
@@ -2097,3 +2118,69 @@ void microcode_check(void)
pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
pr_warn("x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update.\n");
}
+
+void __init arch_cpu_finalize_init(void)
+{
+ identify_boot_cpu();
+
+ /*
+ * identify_boot_cpu() initialized SMT support information, let the
+ * core code know.
+ */
+ cpu_smt_check_topology();
+
+ if (!IS_ENABLED(CONFIG_SMP)) {
+ pr_info("CPU: ");
+ print_cpu_info(&boot_cpu_data);
+ }
+
+ cpu_select_mitigations();
+
+ arch_smt_update();
+
+ if (IS_ENABLED(CONFIG_X86_32)) {
+ /*
+ * Check whether this is a real i386 which is not longer
+ * supported and fixup the utsname.
+ */
+ if (boot_cpu_data.x86 < 4)
+ panic("Kernel requires i486+ for 'invlpg' and other features");
+
+ init_utsname()->machine[1] =
+ '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
+ }
+
+ /*
+ * Must be before alternatives because it might set or clear
+ * feature bits.
+ */
+ fpu__init_system();
+ fpu__init_cpu();
+
+ alternative_instructions();
+
+ if (IS_ENABLED(CONFIG_X86_64)) {
+ /*
+ * Make sure the first 2MB area is not mapped by huge pages
+ * There are typically fixed size MTRRs in there and overlapping
+ * MTRRs into large pages causes slow downs.
+ *
+ * Right now we don't do that with gbpages because there seems
+ * very little benefit for that case.
+ */
+ if (!direct_gbpages)
+ set_memory_4k((unsigned long)__va(0), 1);
+ } else {
+ fpu__init_check_bugs();
+ }
+
+ /*
+ * This needs to be called before any devices perform DMA
+ * operations that might use the SWIOTLB bounce buffers. It will
+ * mark the bounce buffers as decrypted so that their usage will
+ * not cause "plain-text" data to be decrypted when accessed. It
+ * must be called after late_time_init() so that Hyper-V x86/x64
+ * hypercalls work when the SWIOTLB bounce buffers are decrypted.
+ */
+ mem_encrypt_init();
+}
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 4eb9bf68b122..ca1b8bf380a2 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -79,9 +79,11 @@ extern void detect_ht(struct cpuinfo_x86 *c);
extern void check_null_seg_clears_base(struct cpuinfo_x86 *c);
unsigned int aperfmperf_get_khz(int cpu);
+void cpu_select_mitigations(void);
extern void x86_spec_ctrl_setup_ap(void);
extern void update_srbds_msr(void);
+extern void update_gds_msr(void);
extern u64 x86_read_arch_cap_msr(void);
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 9692ccc583bb..644372a10c89 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -49,7 +49,7 @@ void fpu__init_cpu(void)
fpu__init_cpu_xstate();
}
-static bool fpu__probe_without_cpuid(void)
+static bool __init fpu__probe_without_cpuid(void)
{
unsigned long cr0;
u16 fsw, fcw;
@@ -67,7 +67,7 @@ static bool fpu__probe_without_cpuid(void)
return fsw == 0 && (fcw & 0x103f) == 0x003f;
}
-static void fpu__init_system_early_generic(struct cpuinfo_x86 *c)
+static void __init fpu__init_system_early_generic(void)
{
if (!boot_cpu_has(X86_FEATURE_CPUID) &&
!test_bit(X86_FEATURE_FPU, (unsigned long *)cpu_caps_cleared)) {
@@ -297,10 +297,10 @@ static void __init fpu__init_parse_early_param(void)
* Called on the boot CPU once per system bootup, to set up the initial
* FPU state that is later cloned into all processes:
*/
-void __init fpu__init_system(struct cpuinfo_x86 *c)
+void __init fpu__init_system(void)
{
fpu__init_parse_early_param();
- fpu__init_system_early_generic(c);
+ fpu__init_system_early_generic();
/*
* The FPU has to be operational for some of the
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 8783d065f927..1f1298f6cbc2 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -231,6 +231,7 @@ static void notrace start_secondary(void *unused)
#endif
load_current_idt();
cpu_init();
+ fpu__init_cpu();
x86_cpuinit.early_percpu_clock_init();
preempt_disable();
smp_callin();
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ff7ec9b507e3..cdf2cb1eb923 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -217,6 +217,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
u64 __read_mostly host_xcr0;
+extern bool gds_ucode_mitigated(void);
+
static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt);
static inline void kvm_async_pf_hash_reset(struct kvm_vcpu *vcpu)
@@ -1224,6 +1226,9 @@ u64 kvm_get_arch_capabilities(void)
/* Guests don't need to know "Fill buffer clear control" exists */
data &= ~ARCH_CAP_FB_CLEAR_CTRL;
+ if (!boot_cpu_has_bug(X86_BUG_GDS) || gds_ucode_mitigated())
+ data |= ARCH_CAP_GDS_NO;
+
return data;
}
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 75807c2a1e17..66f83562d329 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -27,6 +27,7 @@
#include <asm/desc.h>
#include <asm/pgtable.h>
#include <asm/cpu.h>
+#include <asm/fpu/internal.h>
#include <xen/interface/xen.h>
#include <xen/interface/vcpu.h>
@@ -58,6 +59,7 @@ static void cpu_bringup(void)
int cpu;
cpu_init();
+ fpu__init_cpu();
touch_softlockup_watchdog();
preempt_disable();
diff --git a/arch/xtensa/include/asm/bugs.h b/arch/xtensa/include/asm/bugs.h
deleted file mode 100644
index 69b29d198249..000000000000
--- a/arch/xtensa/include/asm/bugs.h
+++ /dev/null
@@ -1,18 +0,0 @@
-/*
- * include/asm-xtensa/bugs.h
- *
- * This is included by init/main.c to check for architecture-dependent bugs.
- *
- * Xtensa processors don't have any bugs. :)
- *
- * This file is subject to the terms and conditions of the GNU General
- * Public License. See the file "COPYING" in the main directory of
- * this archive for more details.
- */
-
-#ifndef _XTENSA_BUGS_H
-#define _XTENSA_BUGS_H
-
-static void check_bugs(void) { }
-
-#endif /* _XTENSA_BUGS_H */
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 878ed43d8753..b1bb6f43f896 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -584,6 +584,12 @@ ssize_t __weak cpu_show_retbleed(struct device *dev,
return sysfs_emit(buf, "Not affected\n");
}
+ssize_t __weak cpu_show_gds(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "Not affected\n");
+}
+
static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
@@ -595,6 +601,7 @@ static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);
static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL);
+static DEVICE_ATTR(gather_data_sampling, 0444, cpu_show_gds, NULL);
static struct attribute *cpu_root_vulnerabilities_attrs[] = {
&dev_attr_meltdown.attr,
@@ -608,6 +615,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = {
&dev_attr_srbds.attr,
&dev_attr_mmio_stale_data.attr,
&dev_attr_retbleed.attr,
+ &dev_attr_gather_data_sampling.attr,
NULL
};
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index d2b79d7c0b88..6faf36bfdeaf 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -389,7 +389,7 @@ static void xenvif_get_requests(struct xenvif_queue *queue,
struct gnttab_map_grant_ref *gop = queue->tx_map_ops + *map_ops;
struct xen_netif_tx_request *txp = first;
- nr_slots = shinfo->nr_frags + 1;
+ nr_slots = shinfo->nr_frags + frag_overflow + 1;
copy_count(skb) = 0;
XENVIF_TX_CB(skb)->split_mask = 0;
@@ -455,8 +455,8 @@ static void xenvif_get_requests(struct xenvif_queue *queue,
}
}
- for (shinfo->nr_frags = 0; shinfo->nr_frags < nr_slots;
- shinfo->nr_frags++, gop++) {
+ for (shinfo->nr_frags = 0; nr_slots > 0 && shinfo->nr_frags < MAX_SKB_FRAGS;
+ shinfo->nr_frags++, gop++, nr_slots--) {
index = pending_index(queue->pending_cons++);
pending_idx = queue->pending_ring[index];
xenvif_tx_create_map_op(queue, pending_idx, txp,
@@ -469,12 +469,12 @@ static void xenvif_get_requests(struct xenvif_queue *queue,
txp++;
}
- if (frag_overflow) {
+ if (nr_slots > 0) {
shinfo = skb_shinfo(nskb);
frags = shinfo->frags;
- for (shinfo->nr_frags = 0; shinfo->nr_frags < frag_overflow;
+ for (shinfo->nr_frags = 0; shinfo->nr_frags < nr_slots;
shinfo->nr_frags++, txp++, gop++) {
index = pending_index(queue->pending_cons++);
pending_idx = queue->pending_ring[index];
@@ -485,6 +485,11 @@ static void xenvif_get_requests(struct xenvif_queue *queue,
}
skb_shinfo(skb)->frag_list = nskb;
+ } else if (nskb) {
+ /* A frag_list skb was allocated but it is no longer needed
+ * because enough slots were converted to copy ops above.
+ */
+ kfree_skb(nskb);
}
(*copy_ops) = cop - queue->tx_copy_ops;
diff --git a/include/asm-generic/bugs.h b/include/asm-generic/bugs.h
deleted file mode 100644
index 69021830f078..000000000000
--- a/include/asm-generic/bugs.h
+++ /dev/null
@@ -1,11 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __ASM_GENERIC_BUGS_H
-#define __ASM_GENERIC_BUGS_H
-/*
- * This file is included by 'init/main.c' to check for
- * architecture-dependent bugs.
- */
-
-static inline void check_bugs(void) { }
-
-#endif /* __ASM_GENERIC_BUGS_H */
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 12ed4cb751de..c376a59a3e42 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -170,6 +170,12 @@ void arch_cpu_idle_enter(void);
void arch_cpu_idle_exit(void);
void arch_cpu_idle_dead(void);
+#ifdef CONFIG_ARCH_HAS_CPU_FINALIZE_INIT
+void arch_cpu_finalize_init(void);
+#else
+static inline void arch_cpu_finalize_init(void) { }
+#endif
+
int cpu_report_state(int cpu);
int cpu_check_up_prepare(int cpu);
void cpu_set_state_online(int cpu);
diff --git a/init/main.c b/init/main.c
index 489a5aa7ba53..08c312abbaf1 100644
--- a/init/main.c
+++ b/init/main.c
@@ -91,10 +91,8 @@
#include <linux/cache.h>
#include <linux/rodata_test.h>
#include <linux/jump_label.h>
-#include <linux/mem_encrypt.h>
#include <asm/io.h>
-#include <asm/bugs.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
@@ -493,8 +491,6 @@ void __init __weak thread_stack_cache_init(void)
}
#endif
-void __init __weak mem_encrypt_init(void) { }
-
bool initcall_debug;
core_param(initcall_debug, initcall_debug, bool, 0644);
@@ -674,14 +670,6 @@ asmlinkage __visible void __init start_kernel(void)
*/
locking_selftest();
- /*
- * This needs to be called before any devices perform DMA
- * operations that might use the SWIOTLB bounce buffers. It will
- * mark the bounce buffers as decrypted so that their usage will
- * not cause "plain-text" data to be decrypted when accessed.
- */
- mem_encrypt_init();
-
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
@@ -700,6 +688,9 @@ asmlinkage __visible void __init start_kernel(void)
late_time_init();
sched_clock_init();
calibrate_delay();
+
+ arch_cpu_finalize_init();
+
pid_idr_init();
anon_vma_init();
#ifdef CONFIG_X86
@@ -726,7 +717,6 @@ asmlinkage __visible void __init start_kernel(void)
taskstats_init_early();
delayacct_init();
- check_bugs();
acpi_subsystem_init();
arch_post_acpi_subsys_init();
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