File 64763137-x86-AutoIBRS-definitions.patch of Package xen.34725

Overview Repositories Revisions Requests Users Attributes Meta

File 64763137-x86-AutoIBRS-definitions.patch of Package xen.34725

# Commit 8347d6bb29bfd0c3b5acdc078574a8643c5a5637
# Date 2023-05-30 18:24:07 +0100
# Author Alejandro Vallejo <alejandro.vallejo@cloud.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86: Add bit definitions for Automatic IBRS

This is an AMD feature to reduce the IBRS handling overhead. Once enabled,
processes running at CPL=0 are automatically IBRS-protected even if
SPEC_CTRL.IBRS is not set. Furthermore, the RAS/RSB is cleared on VMEXIT.

The feature is exposed in CPUID and toggled in EFER.

Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

--- a/tools/misc/xen-cpuid.c
+++ b/tools/misc/xen-cpuid.c
@@ -192,6 +192,7 @@ static const char *const str_e21a[32] =
 {
     [ 2] = "lfence+",
     [ 6] = "nscb",
+    [ 8] = "auto-ibrs",
 
     /* 26 */                [27] = "sbpb",
     [28] = "ibpb-brtype",   [29] = "srso-no",
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -128,6 +128,7 @@
 #define cpu_has_amd_ssbd        boot_cpu_has(X86_FEATURE_AMD_SSBD)
 #define cpu_has_virt_ssbd       boot_cpu_has(X86_FEATURE_VIRT_SSBD)
 #define cpu_has_ssb_no          boot_cpu_has(X86_FEATURE_SSB_NO)
+#define cpu_has_auto_ibrs       boot_cpu_has(X86_FEATURE_AUTO_IBRS)
 
 /* CPUID level 0x00000007:0.edx */
 #define cpu_has_avx512_4vnniw   boot_cpu_has(X86_FEATURE_AVX512_4VNNIW)
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -179,6 +179,7 @@
 #define  EFER_NXE                           (_AC(1, ULL) << 11) /* No Execute Enable */
 #define  EFER_SVME                          (_AC(1, ULL) << 12) /* Secure Virtual Machine Enable */
 #define  EFER_FFXSE                         (_AC(1, ULL) << 14) /* Fast FXSAVE/FXRSTOR */
+#define  EFER_AIBRSE                        (_AC(1, ULL) << 21) /* Automatic IBRS Enable */
 
 #define EFER_KNOWN_MASK \
     (EFER_SCE | EFER_LME | EFER_LMA | EFER_NXE | EFER_SVME | EFER_FFXSE)
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -299,6 +299,7 @@ XEN_CPUFEATURE(FSRCS,        10*32+12) /
 /* AMD-defined CPU features, CPUID level 0x80000021.eax, word 11 */
 XEN_CPUFEATURE(LFENCE_DISPATCH,    11*32+ 2) /*A  LFENCE always serializing */
 XEN_CPUFEATURE(NSCB,               11*32+ 6) /*A  Null Selector Clears Base (and limit too) */
+XEN_CPUFEATURE(AUTO_IBRS,          11*32+ 8) /*   Automatic IBRS */
 XEN_CPUFEATURE(SBPB,               11*32+27) /*A  Selective Branch Predictor Barrier */
 XEN_CPUFEATURE(IBPB_BRTYPE,        11*32+28) /*A  IBPB flushes Branch Type predictions too */
 XEN_CPUFEATURE(SRSO_NO,            11*32+29) /*A  Hardware not vulenrable to Speculative Return Stack Overflow */

Places

File 64763137-x86-AutoIBRS-definitions.patch of Package xen.34725

Places