File 5edfbbea-x86-spec-ctrl-CPUID-MSR-defs-for-SRBDS.patch of Package xen.16551
# Commit caab85ab58c0cdf74ab070a5de5c4df89f509ff3
# Date 2020-06-09 17:42:18 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/spec-ctrl: CPUID/MSR definitions for Special Register Buffer Data Sampling
This is part of XSA-320 / CVE-2020-0543
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wl@xen.org>
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -483,10 +483,10 @@ accounting for hardware capabilities as
Currently accepted:
-The Speculation Control hardware features `md-clear`, `ibrsb`, `stibp`, `ibpb`,
-`l1d-flush` and `ssbd` are used by default if available and applicable. They can
-be ignored, e.g. `no-ibrsb`, at which point Xen won't use them itself, and
-won't offer them to guests.
+The Speculation Control hardware features `srbds-ctrl`, `md-clear`, `ibrsb`,
+`stibp`, `ibpb`, `l1d-flush` and `ssbd` are used by default if available and
+applicable. They can be ignored, e.g. `no-ibrsb`, at which point Xen won't
+use them itself, and won't offer them to guests.
`rdrand` can be used to override the default disabling of the feature on certain
AMD systems. Its negative form can of course also be used to suppress use and
--- a/tools/libxl/libxl_cpuid.c
+++ b/tools/libxl/libxl_cpuid.c
@@ -213,6 +213,7 @@ int libxl_cpuid_parse_config(libxl_cpuid
{"avx512-4vnniw",0x00000007, 0, CPUID_REG_EDX, 2, 1},
{"avx512-4fmaps",0x00000007, 0, CPUID_REG_EDX, 3, 1},
+ {"srbds-ctrl", 0x00000007, 0, CPUID_REG_EDX, 9, 1},
{"md-clear", 0x00000007, 0, CPUID_REG_EDX, 10, 1},
{"cet-ibt", 0x00000007, 0, CPUID_REG_EDX, 20, 1},
{"ibrsb", 0x00000007, 0, CPUID_REG_EDX, 26, 1},
--- a/tools/misc/xen-cpuid.c
+++ b/tools/misc/xen-cpuid.c
@@ -157,6 +157,7 @@ static const char *const str_7d0[32] =
[ 2] = "avx512_4vnniw", [ 3] = "avx512_4fmaps",
[ 4] = "fsrm",
+ /* 8 */ [ 9] = "srbds-ctrl",
[10] = "md-clear",
/* 12 */ [13] = "tsx-force-abort",
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -134,6 +134,7 @@ int guest_rdmsr(struct vcpu *v, uint32_t
/* Write-only */
case MSR_TSX_FORCE_ABORT:
case MSR_TSX_CTRL:
+ case MSR_MCU_OPT_CTRL:
case MSR_U_CET:
case MSR_S_CET:
case MSR_PL0_SSP ... MSR_INTERRUPT_SSP_TABLE:
@@ -288,6 +289,7 @@ int guest_wrmsr(struct vcpu *v, uint32_t
/* Read-only */
case MSR_TSX_FORCE_ABORT:
case MSR_TSX_CTRL:
+ case MSR_MCU_OPT_CTRL:
case MSR_U_CET:
case MSR_S_CET:
case MSR_PL0_SSP ... MSR_INTERRUPT_SSP_TABLE:
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -312,12 +312,13 @@ static void __init print_details(enum in
printk("Speculative mitigation facilities:\n");
/* Hardware features which pertain to speculative mitigations. */
- printk(" Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
+ printk(" Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
(_7d0 & cpufeat_mask(X86_FEATURE_IBRSB)) ? " IBRS/IBPB" : "",
(_7d0 & cpufeat_mask(X86_FEATURE_STIBP)) ? " STIBP" : "",
(_7d0 & cpufeat_mask(X86_FEATURE_L1D_FLUSH)) ? " L1D_FLUSH" : "",
(_7d0 & cpufeat_mask(X86_FEATURE_SSBD)) ? " SSBD" : "",
(_7d0 & cpufeat_mask(X86_FEATURE_MD_CLEAR)) ? " MD_CLEAR" : "",
+ (_7d0 & cpufeat_mask(X86_FEATURE_SRBDS_CTRL)) ? " SRBDS_CTRL" : "",
(e8b & cpufeat_mask(X86_FEATURE_IBPB)) ? " IBPB" : "",
(caps & ARCH_CAPS_IBRS_ALL) ? " IBRS_ALL" : "",
(caps & ARCH_CAPS_RDCL_NO) ? " RDCL_NO" : "",
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -179,6 +179,9 @@
#define MSR_IA32_VMX_TRUE_ENTRY_CTLS 0x490
#define MSR_IA32_VMX_VMFUNC 0x491
+#define MSR_MCU_OPT_CTRL 0x00000123
+#define MCU_OPT_CTRL_RNGDS_MITG_DIS (_AC(1, ULL) << 0)
+
#define MSR_U_CET 0x000006a0
#define MSR_S_CET 0x000006a2
#define MSR_PL0_SSP 0x000006a4
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -252,6 +252,7 @@ XEN_CPUFEATURE(IBPB, 8*32+12) /
/* Intel-defined CPU features, CPUID level 0x00000007:0.edx, word 9 */
XEN_CPUFEATURE(AVX512_4VNNIW, 9*32+ 2) /*A AVX512 Neural Network Instructions */
XEN_CPUFEATURE(AVX512_4FMAPS, 9*32+ 3) /*A AVX512 Multiply Accumulation Single Precision */
+XEN_CPUFEATURE(SRBDS_CTRL, 9*32+ 9) /* MSR_MCU_OPT_CTRL and RNGDS_MITG_DIS. */
XEN_CPUFEATURE(MD_CLEAR, 9*32+10) /*A VERW clears microarchitectural buffers */
XEN_CPUFEATURE(TSX_FORCE_ABORT, 9*32+13) /* MSR_TSX_FORCE_ABORT.RTM_ABORT */
XEN_CPUFEATURE(CET_IBT, 9*32+20) /* CET - Indirect Branch Tracking */
