[PATCH 44/60] kvm: x86: Move cpu_caps to struct kvm_vcpu_arch_common
From: Jörg Rödel
Date: Mon Jun 08 2026 - 11:24:52 EST
From: Joerg Roedel <joerg.roedel@xxxxxxx>
Now that CPUID state is shared across all planes, cpu_caps can be
shared as well.
Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 33 +++++++++++++++++----------------
arch/x86/kvm/cpuid.c | 18 +++++++++---------
arch/x86/kvm/cpuid.h | 17 +++++++++--------
arch/x86/kvm/svm/svm.c | 4 ++--
arch/x86/kvm/vmx/vmx.c | 2 +-
5 files changed, 38 insertions(+), 36 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3a64bdae6e23..b0d040528f9d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -800,6 +800,23 @@ struct kvm_vcpu_arch_common {
struct kvm_cpuid_entry2 *cpuid_entries;
bool cpuid_dynamic_bits_dirty;
bool is_amd_compatible;
+
+ /*
+ * cpu_caps holds the effective guest capabilities, i.e. the features
+ * the vCPU is allowed to use. Typically, but not always, features can
+ * be used by the guest if and only if both KVM and userspace want to
+ * expose the feature to the guest.
+ *
+ * A common exception is for virtualization holes, i.e. when KVM can't
+ * prevent the guest from using a feature, in which case the vCPU "has"
+ * the feature regardless of what KVM or userspace desires.
+ *
+ * Note, features that don't require KVM involvement in any way are
+ * NOT enforced/sanitized by KVM, i.e. are taken verbatim from the
+ * guest CPUID provided by userspace.
+ */
+ u32 cpu_caps[NR_KVM_CPU_CAPS];
+
};
int kvm_arch_vcpu_common_init(struct kvm_vcpu_common *common);
@@ -925,22 +942,6 @@ struct kvm_vcpu_arch {
int halt_request; /* real mode on Intel only */
- /*
- * cpu_caps holds the effective guest capabilities, i.e. the features
- * the vCPU is allowed to use. Typically, but not always, features can
- * be used by the guest if and only if both KVM and userspace want to
- * expose the feature to the guest.
- *
- * A common exception is for virtualization holes, i.e. when KVM can't
- * prevent the guest from using a feature, in which case the vCPU "has"
- * the feature regardless of what KVM or userspace desires.
- *
- * Note, features that don't require KVM involvement in any way are
- * NOT enforced/sanitized by KVM, i.e. are taken verbatim from the
- * guest CPUID provided by userspace.
- */
- u32 cpu_caps[NR_KVM_CPU_CAPS];
-
u64 reserved_gpa_bits;
int maxphyaddr;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 6d948d63306c..27e2f7e25038 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -284,7 +284,7 @@ static __always_inline void kvm_update_feature_runtime(struct kvm_vcpu *vcpu,
bool has_feature)
{
cpuid_entry_change(entry, x86_feature, has_feature);
- guest_cpu_cap_change(vcpu, x86_feature, has_feature);
+ guest_cpu_cap_change(vcpu->common, x86_feature, has_feature);
}
static void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
@@ -382,7 +382,7 @@ void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
bool allow_gbpages;
int i;
- memset(vcpu->arch.cpu_caps, 0, sizeof(vcpu->arch.cpu_caps));
+ memset(common->arch.cpu_caps, 0, sizeof(common->arch.cpu_caps));
BUILD_BUG_ON(ARRAY_SIZE(reverse_cpuid) != NR_KVM_CPU_CAPS);
/*
@@ -408,9 +408,9 @@ void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
* in guest CPUID. Note, this includes features that are
* supported by KVM but aren't advertised to userspace!
*/
- vcpu->arch.cpu_caps[i] = kvm_cpu_caps[i] |
- cpuid_get_reg_unsafe(&emulated, cpuid.reg);
- vcpu->arch.cpu_caps[i] &= cpuid_get_reg_unsafe(entry, cpuid.reg);
+ common->arch.cpu_caps[i] = kvm_cpu_caps[i] |
+ cpuid_get_reg_unsafe(&emulated, cpuid.reg);
+ common->arch.cpu_caps[i] &= cpuid_get_reg_unsafe(entry, cpuid.reg);
}
kvm_update_cpuid_runtime(vcpu);
@@ -428,7 +428,7 @@ void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
*/
allow_gbpages = tdp_enabled ? boot_cpu_has(X86_FEATURE_GBPAGES) :
guest_cpu_cap_has(vcpu, X86_FEATURE_GBPAGES);
- guest_cpu_cap_change(vcpu, X86_FEATURE_GBPAGES, allow_gbpages);
+ guest_cpu_cap_change(common, X86_FEATURE_GBPAGES, allow_gbpages);
best = kvm_find_cpuid_entry(vcpu, 1);
if (best && apic) {
@@ -536,8 +536,8 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
swap(common->arch.cpuid_entries, e2);
swap(common->arch.cpuid_nent, nent);
- memcpy(vcpu_caps, vcpu->arch.cpu_caps, sizeof(vcpu_caps));
- BUILD_BUG_ON(sizeof(vcpu_caps) != sizeof(vcpu->arch.cpu_caps));
+ memcpy(vcpu_caps, common->arch.cpu_caps, sizeof(vcpu_caps));
+ BUILD_BUG_ON(sizeof(vcpu_caps) != sizeof(common->arch.cpu_caps));
/*
* KVM does not correctly handle changing guest CPUID after KVM_RUN or
@@ -582,7 +582,7 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
return 0;
err:
- memcpy(vcpu->arch.cpu_caps, vcpu_caps, sizeof(vcpu_caps));
+ memcpy(common->arch.cpu_caps, vcpu_caps, sizeof(vcpu_caps));
swap(common->arch.cpuid_entries, e2);
swap(common->arch.cpuid_nent, nent);
return r;
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 143ea8531611..75abf447eabf 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -239,36 +239,37 @@ static __always_inline bool guest_pv_has(struct kvm_vcpu *vcpu,
return vcpu->arch.pv_cpuid.features & (1u << kvm_feature);
}
-static __always_inline void guest_cpu_cap_set(struct kvm_vcpu *vcpu,
+static __always_inline void guest_cpu_cap_set(struct kvm_vcpu_common *common,
unsigned int x86_feature)
{
unsigned int x86_leaf = __feature_leaf(x86_feature);
- vcpu->arch.cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
+ common->arch.cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
}
-static __always_inline void guest_cpu_cap_clear(struct kvm_vcpu *vcpu,
+static __always_inline void guest_cpu_cap_clear(struct kvm_vcpu_common *common,
unsigned int x86_feature)
{
unsigned int x86_leaf = __feature_leaf(x86_feature);
- vcpu->arch.cpu_caps[x86_leaf] &= ~__feature_bit(x86_feature);
+ common->arch.cpu_caps[x86_leaf] &= ~__feature_bit(x86_feature);
}
-static __always_inline void guest_cpu_cap_change(struct kvm_vcpu *vcpu,
+static __always_inline void guest_cpu_cap_change(struct kvm_vcpu_common *common,
unsigned int x86_feature,
bool guest_has_cap)
{
if (guest_has_cap)
- guest_cpu_cap_set(vcpu, x86_feature);
+ guest_cpu_cap_set(common, x86_feature);
else
- guest_cpu_cap_clear(vcpu, x86_feature);
+ guest_cpu_cap_clear(common, x86_feature);
}
static __always_inline bool guest_cpu_cap_has(struct kvm_vcpu *vcpu,
unsigned int x86_feature)
{
unsigned int x86_leaf = __feature_leaf(x86_feature);
+ struct kvm_vcpu_common *common = vcpu->common;
/*
* Except for MWAIT, querying dynamic feature bits is disallowed, so
@@ -278,7 +279,7 @@ static __always_inline bool guest_cpu_cap_has(struct kvm_vcpu *vcpu,
x86_feature == X86_FEATURE_OSXSAVE ||
x86_feature == X86_FEATURE_OSPKE);
- return vcpu->arch.cpu_caps[x86_leaf] & __feature_bit(x86_feature);
+ return common->arch.cpu_caps[x86_leaf] & __feature_bit(x86_feature);
}
static inline bool kvm_vcpu_is_legal_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 612db7ad8b2a..0b57dde29e40 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4706,7 +4706,7 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
* XSS on VM-Enter/VM-Exit. Failure to do so would effectively give
* the guest read/write access to the host's XSS.
*/
- guest_cpu_cap_change(vcpu, X86_FEATURE_XSAVES,
+ guest_cpu_cap_change(vcpu->common, X86_FEATURE_XSAVES,
boot_cpu_has(X86_FEATURE_XSAVES) &&
guest_cpu_cap_has(vcpu, X86_FEATURE_XSAVE));
@@ -4716,7 +4716,7 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
* SVM on Intel is bonkers and extremely unlikely to work).
*/
if (guest_cpuid_is_intel_compatible(vcpu))
- guest_cpu_cap_clear(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);
+ guest_cpu_cap_clear(vcpu->common, X86_FEATURE_V_VMSAVE_VMLOAD);
if (is_sev_guest(vcpu))
sev_vcpu_after_set_cpuid(svm);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 62e180651143..d10aa5f60cad 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7994,7 +7994,7 @@ void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
* set if and only if XSAVE is supported.
*/
if (!guest_cpu_cap_has(vcpu, X86_FEATURE_XSAVE))
- guest_cpu_cap_clear(vcpu, X86_FEATURE_XSAVES);
+ guest_cpu_cap_clear(vcpu->common, X86_FEATURE_XSAVES);
vmx_setup_uret_msrs(vmx);
--
2.53.0