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Date: Tue, 26 Nov 2019 12:22:34 +0100
From: Borislav Petkov <bp@...e.de>
To: x86-ml <x86@...nel.org>
Cc: lkml <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH] x86: Filter MSR writes from luserspace
Hi,
so this has been on my TODO list for a while. I'd like to disable writes
to certain MSRs and MSR ranges because luserspace has no job poking at
those at all. If there's a need for poking at MSRs, a proper userspace
interface needs to be designed instead of plain writes into the MSRs.
There's a "msr.allow_writes" root-only param for the use case where CPU
folks want to be poking at MSRs. And yes, that is a valid use case -
they wanna be poking at their MSRs.
In any case, writes do taint the kernel now so that it is known that
something has been poking at the MSRs.
Thoughts?
---
... to certain important MSRs.
v0: add allow_writes param for root.
Not-yet-signed-off-by: Borislav Petkov <bp@...e.de>
---
arch/x86/events/amd/power.c | 4 -
arch/x86/events/intel/knc.c | 4 -
arch/x86/include/asm/msr-index.h | 8 ++
arch/x86/include/asm/processor.h | 2 +
arch/x86/kernel/cpu/bugs.c | 2 +-
arch/x86/kernel/cpu/common.c | 165 +++++++++++++++++++++++++++++++
arch/x86/kernel/msr.c | 20 +++-
drivers/hwmon/fam15h_power.c | 4 -
8 files changed, 195 insertions(+), 14 deletions(-)
diff --git a/arch/x86/events/amd/power.c b/arch/x86/events/amd/power.c
index abef51320e3a..0a6a31aff792 100644
--- a/arch/x86/events/amd/power.c
+++ b/arch/x86/events/amd/power.c
@@ -13,10 +13,6 @@
#include <asm/cpu_device_id.h>
#include "../perf_event.h"
-#define MSR_F15H_CU_PWR_ACCUMULATOR 0xc001007a
-#define MSR_F15H_CU_MAX_PWR_ACCUMULATOR 0xc001007b
-#define MSR_F15H_PTSC 0xc0010280
-
/* Event code: LSB 8 bits, passed in attr->config any other bit is reserved. */
#define AMD_POWER_EVENT_MASK 0xFFULL
diff --git a/arch/x86/events/intel/knc.c b/arch/x86/events/intel/knc.c
index 618001c208e8..68ab91524242 100644
--- a/arch/x86/events/intel/knc.c
+++ b/arch/x86/events/intel/knc.c
@@ -148,10 +148,6 @@ static struct event_constraint knc_event_constraints[] =
EVENT_CONSTRAINT_END
};
-#define MSR_KNC_IA32_PERF_GLOBAL_STATUS 0x0000002d
-#define MSR_KNC_IA32_PERF_GLOBAL_OVF_CONTROL 0x0000002e
-#define MSR_KNC_IA32_PERF_GLOBAL_CTRL 0x0000002f
-
#define KNC_ENABLE_COUNTER0 0x00000001
#define KNC_ENABLE_COUNTER1 0x00000002
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 084e98da04a7..04cc381246fd 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -388,6 +388,10 @@
#define MSR_KNC_EVNTSEL0 0x00000028
#define MSR_KNC_EVNTSEL1 0x00000029
+#define MSR_KNC_IA32_PERF_GLOBAL_STATUS 0x0000002d
+#define MSR_KNC_IA32_PERF_GLOBAL_OVF_CONTROL 0x0000002e
+#define MSR_KNC_IA32_PERF_GLOBAL_CTRL 0x0000002f
+
/* Alternative perfctr range with full access. */
#define MSR_IA32_PMC0 0x000004c1
@@ -472,6 +476,10 @@
#define MSR_F15H_IC_CFG 0xc0011021
#define MSR_F15H_EX_CFG 0xc001102c
+#define MSR_F15H_CU_PWR_ACCUMULATOR 0xc001007a
+#define MSR_F15H_CU_MAX_PWR_ACCUMULATOR 0xc001007b
+#define MSR_F15H_PTSC 0xc0010280
+
/* Fam 10h MSRs */
#define MSR_FAM10H_MMIO_CONF_BASE 0xc0010058
#define FAM10H_MMIO_CONF_ENABLE (1<<0)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 54f5d54280f6..77ccb268c545 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -970,6 +970,8 @@ bool xen_set_default_idle(void);
void stop_this_cpu(void *dummy);
void df_debug(struct pt_regs *regs, long error_code);
void microcode_check(void);
+void msr_write_callback(int cpu, u32 reg, u32 low, u32 hi);
+int msr_filter_write(u32 reg);
enum l1tf_mitigations {
L1TF_MITIGATION_OFF,
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 4c7b0fa15a19..86b8cdeb3caa 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -56,7 +56,7 @@ static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS;
* AMD specific MSR info for Speculative Store Bypass control.
* x86_amd_ls_cfg_ssbd_mask is initialized in identify_boot_cpu().
*/
-u64 __ro_after_init x86_amd_ls_cfg_base;
+u64 x86_amd_ls_cfg_base;
u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
/* Control conditional STIBP in switch_to() */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index fffe21945374..0974d0b0feb4 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -53,6 +53,7 @@
#include <asm/microcode_intel.h>
#include <asm/intel-family.h>
#include <asm/cpu_device_id.h>
+#include <asm/spec-ctrl.h>
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/uv/uv.h>
@@ -2000,3 +2001,167 @@ void arch_smt_update(void)
/* Check whether IPI broadcasting can be enabled */
apic_smt_update();
}
+
+void msr_write_callback(int cpu, u32 reg, u32 lo, u32 hi)
+{
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ if (reg == MSR_AMD64_LS_CFG) {
+ u64 new = ((u64)hi << 32) | lo;
+ struct msr msr;
+
+ if (new != x86_amd_ls_cfg_base) {
+ x86_amd_ls_cfg_base = new;
+
+ msr.q = new;
+
+ wrmsr_on_cpus(cpu_online_mask, MSR_AMD64_LS_CFG, &msr);
+ }
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(msr_write_callback);
+
+int msr_filter_write(u32 reg)
+{
+ /* all perf counter MSRs */
+ switch (reg) {
+ case MSR_K7_EVNTSEL0:
+ case MSR_K7_PERFCTR0:
+ case MSR_F15H_PERF_CTL:
+ case MSR_F15H_PERF_CTR:
+ case MSR_AMD64_IBSBRTARGET:
+ case MSR_AMD64_IBSCTL:
+ case MSR_AMD64_IBSFETCHCTL:
+ case MSR_AMD64_IBSOPCTL:
+ case MSR_AMD64_IBSOPDATA4:
+ case MSR_AMD64_IBSOP_REG_COUNT:
+ case MSR_AMD64_IBSOP_REG_MASK:
+ case MSR_AMD64_IBS_REG_COUNT_MAX:
+ case MSR_ARCH_PERFMON_EVENTSEL0:
+ case MSR_ARCH_PERFMON_FIXED_CTR0:
+ case MSR_ARCH_PERFMON_FIXED_CTR_CTRL:
+ case MSR_ARCH_PERFMON_PERFCTR0:
+ case MSR_CORE_C1_RES:
+ case MSR_CORE_C3_RESIDENCY:
+ case MSR_CORE_C6_RESIDENCY:
+ case MSR_CORE_C7_RESIDENCY:
+ case MSR_CORE_PERF_GLOBAL_CTRL:
+ case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
+ case MSR_CORE_PERF_GLOBAL_STATUS:
+ case MSR_DRAM_ENERGY_STATUS:
+ case MSR_F15H_CU_MAX_PWR_ACCUMULATOR:
+ case MSR_F15H_CU_PWR_ACCUMULATOR:
+ case MSR_F15H_NB_PERF_CTL:
+ case MSR_F15H_PTSC:
+ case MSR_F16H_L2I_PERF_CTL:
+ case MSR_F17H_IRPERF:
+ case MSR_IA32_APERF:
+ case MSR_IA32_DEBUGCTLMSR:
+ case MSR_IA32_DS_AREA:
+ case MSR_IA32_MISC_ENABLE:
+ case MSR_IA32_MPERF:
+ case MSR_IA32_PEBS_ENABLE:
+ case MSR_IA32_PERF_CAPABILITIES:
+ case MSR_IA32_PMC0:
+ case MSR_IA32_RTIT_ADDR0_A:
+ case MSR_IA32_RTIT_ADDR0_B:
+ case MSR_IA32_RTIT_ADDR1_A:
+ case MSR_IA32_RTIT_ADDR1_B:
+ case MSR_IA32_RTIT_ADDR2_A:
+ case MSR_IA32_RTIT_ADDR2_B:
+ case MSR_IA32_RTIT_ADDR3_A:
+ case MSR_IA32_RTIT_ADDR3_B:
+ case MSR_IA32_RTIT_CTL:
+ case MSR_IA32_RTIT_OUTPUT_BASE:
+ case MSR_IA32_RTIT_OUTPUT_MASK:
+ case MSR_IA32_RTIT_STATUS:
+ case MSR_IA32_THERM_STATUS:
+ case MSR_IA32_VMX_MISC:
+ case MSR_KNC_EVNTSEL0:
+ case MSR_KNC_IA32_PERF_GLOBAL_CTRL:
+ case MSR_KNC_IA32_PERF_GLOBAL_OVF_CONTROL:
+ case MSR_KNC_IA32_PERF_GLOBAL_STATUS:
+ case MSR_KNC_PERFCTR0:
+ case MSR_KNL_CORE_C6_RESIDENCY:
+ case MSR_LBR_CORE_FROM:
+ case MSR_LBR_CORE_TO:
+ case MSR_LBR_INFO_0:
+ case MSR_LBR_NHM_FROM:
+ case MSR_LBR_NHM_TO:
+ case MSR_LBR_SELECT:
+ case MSR_LBR_TOS:
+ case MSR_OFFCORE_RSP_0:
+ case MSR_OFFCORE_RSP_1:
+ case MSR_P4_ALF_ESCR0:
+ case MSR_P4_ALF_ESCR1:
+ case MSR_P4_BPU_CCCR0:
+ case MSR_P4_BPU_ESCR0:
+ case MSR_P4_BPU_ESCR1:
+ case MSR_P4_BPU_PERFCTR0:
+ case MSR_P4_BSU_ESCR0:
+ case MSR_P4_BSU_ESCR1:
+ case MSR_P4_CRU_ESCR0:
+ case MSR_P4_CRU_ESCR1:
+ case MSR_P4_CRU_ESCR2:
+ case MSR_P4_CRU_ESCR3:
+ case MSR_P4_CRU_ESCR4:
+ case MSR_P4_CRU_ESCR5:
+ case MSR_P4_DAC_ESCR0:
+ case MSR_P4_DAC_ESCR1:
+ case MSR_P4_FIRM_ESCR0:
+ case MSR_P4_FIRM_ESCR1:
+ case MSR_P4_FLAME_ESCR0:
+ case MSR_P4_FLAME_ESCR1:
+ case MSR_P4_FSB_ESCR0:
+ case MSR_P4_FSB_ESCR1:
+ case MSR_P4_IQ_ESCR0:
+ case MSR_P4_IQ_ESCR1:
+ case MSR_P4_IS_ESCR0:
+ case MSR_P4_IS_ESCR1:
+ case MSR_P4_ITLB_ESCR0:
+ case MSR_P4_ITLB_ESCR1:
+ case MSR_P4_IX_ESCR0:
+ case MSR_P4_IX_ESCR1:
+ case MSR_P4_MOB_ESCR0:
+ case MSR_P4_MOB_ESCR1:
+ case MSR_P4_MS_ESCR0:
+ case MSR_P4_MS_ESCR1:
+ case MSR_P4_PEBS_MATRIX_VERT:
+ case MSR_P4_PMH_ESCR0:
+ case MSR_P4_PMH_ESCR1:
+ case MSR_P4_RAT_ESCR0:
+ case MSR_P4_RAT_ESCR1:
+ case MSR_P4_SAAT_ESCR0:
+ case MSR_P4_SAAT_ESCR1:
+ case MSR_P4_SSU_ESCR0:
+ case MSR_P4_SSU_ESCR1:
+ case MSR_P4_TBPU_ESCR0:
+ case MSR_P4_TBPU_ESCR1:
+ case MSR_P4_TC_ESCR0:
+ case MSR_P4_TC_ESCR1:
+ case MSR_P4_U2L_ESCR0:
+ case MSR_P4_U2L_ESCR1:
+ case MSR_PEBS_FRONTEND:
+ case MSR_PEBS_LD_LAT_THRESHOLD:
+ case MSR_PKG_C10_RESIDENCY:
+ case MSR_PKG_C2_RESIDENCY:
+ case MSR_PKG_C3_RESIDENCY:
+ case MSR_PKG_C6_RESIDENCY:
+ case MSR_PKG_C7_RESIDENCY:
+ case MSR_PKG_C8_RESIDENCY:
+ case MSR_PKG_C9_RESIDENCY:
+ case MSR_PKG_ENERGY_STATUS:
+ case MSR_PLATFORM_ENERGY_STATUS:
+ case MSR_PLATFORM_INFO:
+ case MSR_PP0_ENERGY_STATUS:
+ case MSR_PP1_ENERGY_STATUS:
+ case MSR_PPERF:
+ case MSR_RAPL_POWER_UNIT:
+ case MSR_SMI_COUNT:
+ return -EPERM;
+
+ default:
+ return 0;
+ }
+}
+EXPORT_SYMBOL_GPL(msr_filter_write);
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 1547be359d7f..8b87ea3ea680 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -41,6 +41,7 @@
static struct class *msr_class;
static enum cpuhp_state cpuhp_msr_state;
+static bool allow_writes;
static ssize_t msr_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
@@ -84,6 +85,12 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
if (err)
return err;
+ if (!allow_writes) {
+ err = msr_filter_write(reg);
+ if (err)
+ return err;
+ }
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -95,11 +102,20 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
if (err)
break;
+
+ msr_write_callback(cpu, reg, data[0], data[1]);
+
tmp += 2;
bytes += 8;
}
- return bytes ? bytes : err;
+ if (bytes) {
+ add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+
+ return bytes;
+ }
+
+ return err;
}
static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
@@ -242,6 +258,8 @@ static void __exit msr_exit(void)
}
module_exit(msr_exit)
+module_param(allow_writes, bool, 0400);
+
MODULE_AUTHOR("H. Peter Anvin <hpa@...or.com>");
MODULE_DESCRIPTION("x86 generic MSR driver");
MODULE_LICENSE("GPL");
diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
index 267eac00a3fb..29f5fed28c2a 100644
--- a/drivers/hwmon/fam15h_power.c
+++ b/drivers/hwmon/fam15h_power.c
@@ -41,10 +41,6 @@ MODULE_LICENSE("GPL");
/* set maximum interval as 1 second */
#define MAX_INTERVAL 1000
-#define MSR_F15H_CU_PWR_ACCUMULATOR 0xc001007a
-#define MSR_F15H_CU_MAX_PWR_ACCUMULATOR 0xc001007b
-#define MSR_F15H_PTSC 0xc0010280
-
#define PCI_DEVICE_ID_AMD_15H_M70H_NB_F4 0x15b4
struct fam15h_power_data {
--
2.21.0
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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