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x86/cpu: Clear SVM feature if disabled by BIOS

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When SVM is disabled by BIOS, one cannot use KVM but the
SVM feature is still shown in the output of /proc/cpuinfo.
On Intel machines, VMX is cleared by init_ia32_feat_ctl(),
so do the same on AMD and Hygon processors.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230921114940.957141-1-pbonzini@redhat.com
This commit is contained in:
Paolo Bonzini 2023-09-21 07:49:40 -04:00 committed by Borislav Petkov (AMD)
parent ce9ecca023
commit 7deda2ce5b
5 changed files with 25 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
arch/x86/include/asm/msr-index.h
View file

@ -1112,12 +1112,16 @@
#define MSR_IA32_VMX_MISC_INTEL_PT (1ULL << 14)
#define MSR_IA32_VMX_MISC_VMWRITE_SHADOW_RO_FIELDS (1ULL << 29)
#define MSR_IA32_VMX_MISC_PREEMPTION_TIMER_SCALE 0x1F
/* AMD-V MSRs */
/* AMD-V MSRs */
#define MSR_VM_CR 0xc0010114
#define MSR_VM_IGNNE 0xc0010115
#define MSR_VM_HSAVE_PA 0xc0010117
#define SVM_VM_CR_VALID_MASK 0x001fULL
#define SVM_VM_CR_SVM_LOCK_MASK 0x0008ULL
#define SVM_VM_CR_SVM_DIS_MASK 0x0010ULL
/* Hardware Feedback Interface */
#define MSR_IA32_HW_FEEDBACK_PTR 0x17d0
#define MSR_IA32_HW_FEEDBACK_CONFIG 0x17d1

6
arch/x86/include/asm/svm.h
View file

@ -229,10 +229,6 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
#define SVM_IOIO_SIZE_MASK (7 << SVM_IOIO_SIZE_SHIFT)
#define SVM_IOIO_ASIZE_MASK (7 << SVM_IOIO_ASIZE_SHIFT)
#define SVM_VM_CR_VALID_MASK 0x001fULL
#define SVM_VM_CR_SVM_LOCK_MASK 0x0008ULL
#define SVM_VM_CR_SVM_DIS_MASK 0x0010ULL
#define SVM_NESTED_CTL_NP_ENABLE BIT(0)
#define SVM_NESTED_CTL_SEV_ENABLE BIT(1)
#define SVM_NESTED_CTL_SEV_ES_ENABLE BIT(2)
@ -571,8 +567,6 @@ struct vmcb {
#define SVM_CPUID_FUNC 0x8000000a
#define SVM_VM_CR_SVM_DISABLE 4
#define SVM_SELECTOR_S_SHIFT 4
#define SVM_SELECTOR_DPL_SHIFT 5
#define SVM_SELECTOR_P_SHIFT 7

10
arch/x86/kernel/cpu/amd.c
View file

@ -1031,6 +1031,8 @@ static void zenbleed_check(struct cpuinfo_x86 *c)
static void init_amd(struct cpuinfo_x86 *c)
{
u64 vm_cr;
early_init_amd(c);
/*
@ -1082,6 +1084,14 @@ static void init_amd(struct cpuinfo_x86 *c)
init_amd_cacheinfo(c);
if (cpu_has(c, X86_FEATURE_SVM)) {
rdmsrl(MSR_VM_CR, vm_cr);
if (vm_cr & SVM_VM_CR_SVM_DIS_MASK) {
pr_notice_once("SVM disabled (by BIOS) in MSR_VM_CR\n");
clear_cpu_cap(c, X86_FEATURE_SVM);
}
}
if (!cpu_has(c, X86_FEATURE_LFENCE_RDTSC) && cpu_has(c, X86_FEATURE_XMM2)) {
/*
* Use LFENCE for execution serialization. On families which

10
arch/x86/kernel/cpu/hygon.c
View file

@ -290,6 +290,8 @@ static void early_init_hygon(struct cpuinfo_x86 *c)
static void init_hygon(struct cpuinfo_x86 *c)
{
u64 vm_cr;
early_init_hygon(c);
/*
@ -320,6 +322,14 @@ static void init_hygon(struct cpuinfo_x86 *c)
init_hygon_cacheinfo(c);
if (cpu_has(c, X86_FEATURE_SVM)) {
rdmsrl(MSR_VM_CR, vm_cr);
if (vm_cr & SVM_VM_CR_SVM_DIS_MASK) {
pr_notice_once("SVM disabled (by BIOS) in MSR_VM_CR\n");
clear_cpu_cap(c, X86_FEATURE_SVM);
}
}
if (cpu_has(c, X86_FEATURE_XMM2)) {
/*
* Use LFENCE for execution serialization. On families which

8
arch/x86/kvm/svm/svm.c
View file

@ -531,8 +531,6 @@ static bool __kvm_is_svm_supported(void)
int cpu = smp_processor_id();
struct cpuinfo_x86 *c = &cpu_data(cpu);
u64 vm_cr;
if (c->x86_vendor != X86_VENDOR_AMD &&
c->x86_vendor != X86_VENDOR_HYGON) {
pr_err("CPU %d isn't AMD or Hygon\n", cpu);
@ -549,12 +547,6 @@ static bool __kvm_is_svm_supported(void)
return false;
}
rdmsrl(MSR_VM_CR, vm_cr);
if (vm_cr & (1 << SVM_VM_CR_SVM_DISABLE)) {
pr_err("SVM disabled (by BIOS) in MSR_VM_CR on CPU %d\n", cpu);
return false;
}
return true;
}