[PATCH v3 5/5] KVM: x86: Move supported EFER bits to kvm_caps
From: Yosry Ahmed
Date: Mon Jul 13 2026 - 14:11:24 EST
Supported EFER bits naturally fits into kvm_caps because it gets
recomputed during vendor initialization (e.g. to account for EFER.SVME
being allowed/disallowed based on nested being enabled/disabled). Move
efer_supported_bits into kvm_caps as supported_efer_bits (for naming
consistency).
As the bitmask is now globally visible as part of kvm_caps, there's
little use for helpers to enable/disable specific bits, so drop them and
open-code updates to kvm_caps.supported_efer_bits.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx>
Signed-off-by: Yosry Ahmed <yosry@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/msrs.c | 19 ++-----------------
arch/x86/kvm/msrs.h | 2 --
arch/x86/kvm/x86.c | 15 ++++++++-------
4 files changed, 12 insertions(+), 26 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 58f156ae31e75..80b92ed440fa1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -274,6 +274,8 @@ struct kvm_caps {
u64 supported_xss;
u64 supported_perf_cap;
+ u64 supported_efer_bits;
+
u64 supported_quirks;
u64 inapplicable_quirks;
};
diff --git a/arch/x86/kvm/msrs.c b/arch/x86/kvm/msrs.c
index 8e33b87b5e8f0..66fa7140d65d9 100644
--- a/arch/x86/kvm/msrs.c
+++ b/arch/x86/kvm/msrs.c
@@ -19,8 +19,6 @@ bool __read_mostly report_ignored_msrs = true;
module_param(report_ignored_msrs, bool, 0644);
EXPORT_SYMBOL_FOR_KVM_INTERNAL(report_ignored_msrs);
-static u64 __read_mostly efer_supported_bits;
-
#define MAX_IO_MSRS 256
struct msr_bitmap_range {
@@ -605,7 +603,7 @@ static bool __kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
}
bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
{
- if (efer & ~efer_supported_bits)
+ if (efer & ~kvm_caps.supported_efer_bits)
return false;
return __kvm_valid_efer(vcpu, efer);
@@ -618,7 +616,7 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
u64 efer = msr_info->data;
int r;
- if (efer & ~efer_supported_bits)
+ if (efer & ~kvm_caps.supported_efer_bits)
return 1;
if (!msr_info->host_initiated) {
@@ -649,19 +647,6 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
return 0;
}
-void kvm_init_efer_bits(void)
-{
- /* Enable syscall by default because its emulated by KVM */
- efer_supported_bits = (u64)EFER_SCE;
-}
-EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_efer_bits);
-
-void kvm_enable_efer_bits(u64 mask)
-{
- efer_supported_bits |= mask;
-}
-EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_enable_efer_bits);
-
bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type)
{
struct kvm_x86_msr_filter *msr_filter;
diff --git a/arch/x86/kvm/msrs.h b/arch/x86/kvm/msrs.h
index 1f772e1717588..7cc182a15b3b3 100644
--- a/arch/x86/kvm/msrs.h
+++ b/arch/x86/kvm/msrs.h
@@ -58,8 +58,6 @@ int kvm_get_set_one_reg(struct kvm_vcpu *vcpu, unsigned int ioctl,
int kvm_get_reg_list(struct kvm_vcpu *vcpu,
struct kvm_reg_list __user *user_list);
-void kvm_init_efer_bits(void);
-void kvm_enable_efer_bits(u64);
bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
int kvm_emulate_msr_read(struct kvm_vcpu *vcpu, u32 index, u64 *data);
int kvm_emulate_msr_write(struct kvm_vcpu *vcpu, u32 index, u64 data);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 83f608dad0605..a020b1cbb3f3e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6913,24 +6913,25 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_setup_xss_caps);
static void kvm_setup_efer_caps(void)
{
- kvm_init_efer_bits();
+ /* Enable syscall by default because its emulated by KVM */
+ kvm_caps.supported_efer_bits = (u64)EFER_SCE;
if (kvm_cpu_cap_has(X86_FEATURE_LM))
- kvm_enable_efer_bits(EFER_LME | EFER_LMA);
+ kvm_caps.supported_efer_bits |= (EFER_LME | EFER_LMA);
if (kvm_cpu_cap_has(X86_FEATURE_NX))
- kvm_enable_efer_bits(EFER_NX);
+ kvm_caps.supported_efer_bits |= EFER_NX;
if (kvm_cpu_cap_has(X86_FEATURE_FXSR_OPT))
- kvm_enable_efer_bits(EFER_FFXSR);
+ kvm_caps.supported_efer_bits |= EFER_FFXSR;
if (kvm_cpu_cap_has(X86_FEATURE_AUTOIBRS))
- kvm_enable_efer_bits(EFER_AUTOIBRS);
+ kvm_caps.supported_efer_bits |= EFER_AUTOIBRS;
if (kvm_cpu_cap_has(X86_FEATURE_SVM)) {
- kvm_enable_efer_bits(EFER_SVME);
+ kvm_caps.supported_efer_bits |= EFER_SVME;
if (!boot_cpu_has(X86_FEATURE_EFER_LMSLE_MBZ))
- kvm_enable_efer_bits(EFER_LMSLE);
+ kvm_caps.supported_efer_bits |= EFER_LMSLE;
}
}
--
2.55.0.141.g00534a21ce-goog