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Message-Id: <20230921114940.957141-1-pbonzini@redhat.com>
Date: Thu, 21 Sep 2023 07:49:40 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: bp@...en8.de
Subject: [PATCH] x86/cpu: clear SVM feature if disabled by BIOS
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@...hat.com>
---
arch/x86/include/asm/msr-index.h | 6 +++++-
arch/x86/include/asm/svm.h | 6 ------
arch/x86/kernel/cpu/amd.c | 10 ++++++++++
arch/x86/kernel/cpu/hygon.c | 10 ++++++++++
arch/x86/kvm/svm/svm.c | 8 --------
5 files changed, 25 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 1d111350197f..6a6b0f763f67 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -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
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 19bf955b67e0..fb8366af59da 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -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
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index dd8379d84445..1011ce20f513 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -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
diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c
index defdc594be14..16f34639ecf7 100644
--- a/arch/x86/kernel/cpu/hygon.c
+++ b/arch/x86/kernel/cpu/hygon.c
@@ -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
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f283eb47f6ac..7b91efb72ea6 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -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;
}
--
2.39.1
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