The following commit has been merged into the x86/cpu branch of tip: Commit-ID: 639475d434b88b58827e1aae601ed1853803f5be Gitweb: https://git.kernel.org/tip/639475d434b88b58827e1aae601ed1853803f5be Author: Marcos Del Sol Vives <marcos@xxxxxxxx> AuthorDate: Sun, 17 Oct 2021 11:44:10 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Thu, 21 Oct 2021 15:49:07 +02:00 x86/CPU: Add support for Vortex CPUs 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. Add identification for some devices that lack the CPUID product name call, so they appear properly on /proc/cpuinfo. ¹https://www.ssv-embedded.de/doks/infos/DMP_Ann_180108_Meltdown.pdf [ bp: Massage commit message. ] Signed-off-by: Marcos Del Sol Vives <marcos@xxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lkml.kernel.org/r/20211017094408.1512158-1-marcos@xxxxxxxx --- 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 814fe0d..eefc434 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 9ad2aca..64e5290 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 637b499..9661e3e 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 0f88859..325d602 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 0000000..e268547 --- /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);
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