Re: [PATCH v15 03/26] x86/fpu/xstate: Introduce CET MSR XSAVES supervisor states
From: Borislav Petkov <bp@alien8.de>
Date: 2020-11-26 11:02:20
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linux-arch, linux-doc, linux-mm, lkml
On Tue, Nov 10, 2020 at 08:21:48AM -0800, Yu-cheng Yu wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 972a34d93505..6f05ab2a1fa4 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h@@ -922,4 +922,24 @@ #define MSR_VM_IGNNE 0xc0010115 #define MSR_VM_HSAVE_PA 0xc0010117 +/* Control-flow Enforcement Technology MSRs */ +#define MSR_IA32_U_CET 0x6a0 /* user mode cet setting */ +#define MSR_IA32_S_CET 0x6a2 /* kernel mode cet setting */ +#define MSR_IA32_PL0_SSP 0x6a4 /* kernel shstk pointer */ +#define MSR_IA32_PL1_SSP 0x6a5 /* ring-1 shstk pointer */ +#define MSR_IA32_PL2_SSP 0x6a6 /* ring-2 shstk pointer */ +#define MSR_IA32_PL3_SSP 0x6a7 /* user shstk pointer */ +#define MSR_IA32_INT_SSP_TAB 0x6a8 /* exception shstk table */ + +/* MSR_IA32_U_CET and MSR_IA32_S_CET bits */
Pls put the bit defines under the MSRs they belong to.
+#define CET_SHSTK_EN BIT_ULL(0) +#define CET_WRSS_EN BIT_ULL(1) +#define CET_ENDBR_EN BIT_ULL(2) +#define CET_LEG_IW_EN BIT_ULL(3) +#define CET_NO_TRACK_EN BIT_ULL(4) +#define CET_SUPPRESS_DISABLE BIT_ULL(5) +#define CET_RESERVED (BIT_ULL(6) | BIT_ULL(7) | BIT_ULL(8) | BIT_ULL(9)) +#define CET_SUPPRESS BIT_ULL(10) +#define CET_WAIT_ENDBR BIT_ULL(11)
...
* Clear XSAVE features that are disabled in the normal CPUID.
*/
for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
- if (!boot_cpu_has(xsave_cpuid_features[i]))
- xfeatures_mask_all &= ~BIT_ULL(i);
+ if (xsave_cpuid_features[i] == X86_FEATURE_SHSTK) {
+ /*
+ * X86_FEATURE_SHSTK and X86_FEATURE_IBT share
+ * same states, but can be enabled separately.
+ */
+ if (!boot_cpu_has(X86_FEATURE_SHSTK) &&
+ !boot_cpu_has(X86_FEATURE_IBT))
+ xfeatures_mask_all &= ~BIT_ULL(i);
+ } else {
+ if ((xsave_cpuid_features[i] == -1) || ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
That is a new check. I guess it could be done first to simplify the
code:
for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
if (xsave_cpuid_features[i] == -1) {
xfeatures_mask_all &= ~BIT_ULL(i);
continue;
}
/* the rest of the bla */
Yes?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette