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Date: Sun, 17 Oct 2021 11:44:10 +0200 From: Marcos Del Sol Vives <marcos@...a.pet> To: x86@...nel.org Cc: Marcos Del Sol Vives <marcos@...a.pet>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org Subject: [PATCH v2] x86: add support DM&P devices DM&P devices were not being properly identified, which resulted in unneeded Spectre/Meltdown mitigations being applied. The manufacturer states that these devices execute always in-order and don't support either speculative execution or branch prediction, so they are not vulnerable to this class of attack. [1] This is something I've personally tested by a simple timing analysis on my Vortex86MX CPU, and can confirm it is true. Identification for some devices that lack the CPUID product name call has also been added, so they appear properly on /proc/cpuinfo. 1: https://www.ssv-embedded.de/doks/infos/DMP_Ann_180108_Meltdown.pdf Signed-off-by: Marcos Del Sol Vives <marcos@...a.pet> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Ingo Molnar <mingo@...hat.com> Cc: Borislav Petkov <bp@...en8.de> Cc: "H. Peter Anvin" <hpa@...or.com> Cc: linux-kernel@...r.kernel.org --- arch/x86/Kconfig.cpu | 13 +++++++++++ arch/x86/include/asm/processor.h | 3 ++- arch/x86/kernel/cpu/Makefile | 1 + arch/x86/kernel/cpu/common.c | 2 ++ arch/x86/kernel/cpu/vortex.c | 39 ++++++++++++++++++++++++++++++++ 5 files changed, 57 insertions(+), 1 deletion(-) create mode 100644 arch/x86/kernel/cpu/vortex.c diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu index 814fe0d349b0..eefc434351db 100644 --- a/arch/x86/Kconfig.cpu +++ b/arch/x86/Kconfig.cpu @@ -508,3 +508,16 @@ config CPU_SUP_ZHAOXIN CPU might render the kernel unbootable. If unsure, say N. + +config CPU_SUP_VORTEX_32 + default y + bool "Support Vortex processors" if PROCESSOR_SELECT + depends on X86_32 + help + This enables detection, tunings and quirks for Vortex processors + + You need this enabled if you want your kernel to run on a + Vortex CPU. Disabling this option on other types of CPUs + makes the kernel a tiny bit smaller. + + If unsure, say N. diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 9ad2acaaae9b..64e5290b29d0 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -164,7 +164,8 @@ enum cpuid_regs_idx { #define X86_VENDOR_NSC 8 #define X86_VENDOR_HYGON 9 #define X86_VENDOR_ZHAOXIN 10 -#define X86_VENDOR_NUM 11 +#define X86_VENDOR_VORTEX 11 +#define X86_VENDOR_NUM 12 #define X86_VENDOR_UNKNOWN 0xff diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile index 637b499450d1..9661e3e802be 100644 --- a/arch/x86/kernel/cpu/Makefile +++ b/arch/x86/kernel/cpu/Makefile @@ -43,6 +43,7 @@ obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o obj-$(CONFIG_CPU_SUP_ZHAOXIN) += zhaoxin.o +obj-$(CONFIG_CPU_SUP_VORTEX_32) += vortex.o obj-$(CONFIG_X86_MCE) += mce/ obj-$(CONFIG_MTRR) += mtrr/ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 0f8885949e8c..325d6022599b 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1044,6 +1044,8 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = { VULNWL(CENTAUR, 5, X86_MODEL_ANY, NO_SPECULATION), VULNWL(INTEL, 5, X86_MODEL_ANY, NO_SPECULATION), VULNWL(NSC, 5, X86_MODEL_ANY, NO_SPECULATION), + VULNWL(VORTEX, 5, X86_MODEL_ANY, NO_SPECULATION), + VULNWL(VORTEX, 6, X86_MODEL_ANY, NO_SPECULATION), /* Intel Family 6 */ VULNWL_INTEL(ATOM_SALTWELL, NO_SPECULATION | NO_ITLB_MULTIHIT), diff --git a/arch/x86/kernel/cpu/vortex.c b/arch/x86/kernel/cpu/vortex.c new file mode 100644 index 000000000000..e2685470ba94 --- /dev/null +++ b/arch/x86/kernel/cpu/vortex.c @@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/kernel.h> +#include <asm/processor.h> +#include "cpu.h" + +/* + * No special init required for Vortex processors. + */ + +static const struct cpu_dev vortex_cpu_dev = { + .c_vendor = "Vortex", + .c_ident = { "Vortex86 SoC" }, + .legacy_models = { + { + .family = 5, + .model_names = { + [2] = "Vortex86DX", + [8] = "Vortex86MX", + }, + }, + { + .family = 6, + .model_names = { + /* + * Both the Vortex86EX and the Vortex86EX2 + * have the same family and model id. + * + * However, the -EX2 supports the product name + * CPUID call, so this name will only be used + * for the -EX, which does not. + */ + [0] = "Vortex86EX", + }, + }, + }, + .c_x86_vendor = X86_VENDOR_VORTEX, +}; + +cpu_dev_register(vortex_cpu_dev); -- 2.25.1
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