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Diffstat (limited to 'arch/x86/kvm/cpuid.h')
-rw-r--r--arch/x86/kvm/cpuid.h170
1 files changed, 93 insertions, 77 deletions
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index f16a7b2c2adc..d3f5ae15a7ca 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -10,12 +10,35 @@
extern u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly;
void kvm_set_cpu_caps(void);
-void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu);
-void kvm_update_pv_runtime(struct kvm_vcpu *vcpu);
-struct kvm_cpuid_entry2 *kvm_find_cpuid_entry_index(struct kvm_vcpu *vcpu,
- u32 function, u32 index);
-struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
- u32 function);
+void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu);
+struct kvm_cpuid_entry2 *kvm_find_cpuid_entry2(struct kvm_cpuid_entry2 *entries,
+ int nent, u32 function, u64 index);
+/*
+ * Magic value used by KVM when querying userspace-provided CPUID entries and
+ * doesn't care about the CPIUD index because the index of the function in
+ * question is not significant. Note, this magic value must have at least one
+ * bit set in bits[63:32] and must be consumed as a u64 by kvm_find_cpuid_entry2()
+ * to avoid false positives when processing guest CPUID input.
+ *
+ * KVM_CPUID_INDEX_NOT_SIGNIFICANT should never be used directly outside of
+ * kvm_find_cpuid_entry2() and kvm_find_cpuid_entry().
+ */
+#define KVM_CPUID_INDEX_NOT_SIGNIFICANT -1ull
+
+static inline struct kvm_cpuid_entry2 *kvm_find_cpuid_entry_index(struct kvm_vcpu *vcpu,
+ u32 function, u32 index)
+{
+ return kvm_find_cpuid_entry2(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,
+ function, index);
+}
+
+static inline struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
+ u32 function)
+{
+ return kvm_find_cpuid_entry2(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,
+ function, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
+}
+
int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 __user *entries,
unsigned int type);
@@ -35,6 +58,7 @@ void __init kvm_init_xstate_sizes(void);
u32 xstate_required_size(u64 xstate_bv, bool compacted);
int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu);
+int cpuid_query_maxguestphyaddr(struct kvm_vcpu *vcpu);
u64 kvm_vcpu_reserved_gpa_bits_raw(struct kvm_vcpu *vcpu);
static inline int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
@@ -67,41 +91,40 @@ static __always_inline void cpuid_entry_override(struct kvm_cpuid_entry2 *entry,
*reg = kvm_cpu_caps[leaf];
}
-static __always_inline u32 *guest_cpuid_get_register(struct kvm_vcpu *vcpu,
- unsigned int x86_feature)
+static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu,
+ unsigned int x86_feature)
{
const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
struct kvm_cpuid_entry2 *entry;
+ u32 *reg;
+
+ /*
+ * XSAVES is a special snowflake. Due to lack of a dedicated intercept
+ * on SVM, KVM must assume that XSAVES (and thus XRSTORS) is usable by
+ * the guest if the host supports XSAVES and *XSAVE* is exposed to the
+ * guest. Because the guest can execute XSAVES and XRSTORS, i.e. can
+ * indirectly consume XSS, KVM must ensure XSS is zeroed when running
+ * the guest, i.e. must set XSAVES in vCPU capabilities. But to reject
+ * direct XSS reads and writes (to minimize the virtualization hole and
+ * honor userspace's CPUID), KVM needs to check the raw guest CPUID,
+ * not KVM's view of guest capabilities.
+ *
+ * For all other features, guest capabilities are accurate. Expand
+ * this allowlist with extreme vigilance.
+ */
+ BUILD_BUG_ON(x86_feature != X86_FEATURE_XSAVES);
entry = kvm_find_cpuid_entry_index(vcpu, cpuid.function, cpuid.index);
if (!entry)
return NULL;
- return __cpuid_entry_get_reg(entry, cpuid.reg);
-}
-
-static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu,
- unsigned int x86_feature)
-{
- u32 *reg;
-
- reg = guest_cpuid_get_register(vcpu, x86_feature);
+ reg = __cpuid_entry_get_reg(entry, cpuid.reg);
if (!reg)
return false;
return *reg & __feature_bit(x86_feature);
}
-static __always_inline void guest_cpuid_clear(struct kvm_vcpu *vcpu,
- unsigned int x86_feature)
-{
- u32 *reg;
-
- reg = guest_cpuid_get_register(vcpu, x86_feature);
- if (reg)
- *reg &= ~__feature_bit(x86_feature);
-}
-
static inline bool guest_cpuid_is_amd_compatible(struct kvm_vcpu *vcpu)
{
return vcpu->arch.is_amd_compatible;
@@ -150,21 +173,6 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu)
return x86_stepping(best->eax);
}
-static inline bool guest_has_spec_ctrl_msr(struct kvm_vcpu *vcpu)
-{
- return (guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) ||
- guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) ||
- guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) ||
- guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD));
-}
-
-static inline bool guest_has_pred_cmd_msr(struct kvm_vcpu *vcpu)
-{
- return (guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) ||
- guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBPB) ||
- guest_cpuid_has(vcpu, X86_FEATURE_SBPB));
-}
-
static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu)
{
return vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT;
@@ -180,7 +188,6 @@ static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature)
{
unsigned int x86_leaf = __feature_leaf(x86_feature);
- reverse_cpuid_check(x86_leaf);
kvm_cpu_caps[x86_leaf] &= ~__feature_bit(x86_feature);
}
@@ -188,7 +195,6 @@ static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature)
{
unsigned int x86_leaf = __feature_leaf(x86_feature);
- reverse_cpuid_check(x86_leaf);
kvm_cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
}
@@ -196,7 +202,6 @@ static __always_inline u32 kvm_cpu_cap_get(unsigned int x86_feature)
{
unsigned int x86_leaf = __feature_leaf(x86_feature);
- reverse_cpuid_check(x86_leaf);
return kvm_cpu_caps[x86_leaf] & __feature_bit(x86_feature);
}
@@ -220,58 +225,69 @@ static __always_inline bool guest_pv_has(struct kvm_vcpu *vcpu,
return vcpu->arch.pv_cpuid.features & (1u << kvm_feature);
}
-enum kvm_governed_features {
-#define KVM_GOVERNED_FEATURE(x) KVM_GOVERNED_##x,
-#include "governed_features.h"
- KVM_NR_GOVERNED_FEATURES
-};
-
-static __always_inline int kvm_governed_feature_index(unsigned int x86_feature)
+static __always_inline void guest_cpu_cap_set(struct kvm_vcpu *vcpu,
+ unsigned int x86_feature)
{
- switch (x86_feature) {
-#define KVM_GOVERNED_FEATURE(x) case x: return KVM_GOVERNED_##x;
-#include "governed_features.h"
- default:
- return -1;
- }
-}
+ unsigned int x86_leaf = __feature_leaf(x86_feature);
-static __always_inline bool kvm_is_governed_feature(unsigned int x86_feature)
-{
- return kvm_governed_feature_index(x86_feature) >= 0;
+ vcpu->arch.cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
}
-static __always_inline void kvm_governed_feature_set(struct kvm_vcpu *vcpu,
- unsigned int x86_feature)
+static __always_inline void guest_cpu_cap_clear(struct kvm_vcpu *vcpu,
+ unsigned int x86_feature)
{
- BUILD_BUG_ON(!kvm_is_governed_feature(x86_feature));
+ unsigned int x86_leaf = __feature_leaf(x86_feature);
- __set_bit(kvm_governed_feature_index(x86_feature),
- vcpu->arch.governed_features.enabled);
+ vcpu->arch.cpu_caps[x86_leaf] &= ~__feature_bit(x86_feature);
}
-static __always_inline void kvm_governed_feature_check_and_set(struct kvm_vcpu *vcpu,
- unsigned int x86_feature)
+static __always_inline void guest_cpu_cap_change(struct kvm_vcpu *vcpu,
+ unsigned int x86_feature,
+ bool guest_has_cap)
{
- if (kvm_cpu_cap_has(x86_feature) && guest_cpuid_has(vcpu, x86_feature))
- kvm_governed_feature_set(vcpu, x86_feature);
+ if (guest_has_cap)
+ guest_cpu_cap_set(vcpu, x86_feature);
+ else
+ guest_cpu_cap_clear(vcpu, x86_feature);
}
-static __always_inline bool guest_can_use(struct kvm_vcpu *vcpu,
- unsigned int x86_feature)
+static __always_inline bool guest_cpu_cap_has(struct kvm_vcpu *vcpu,
+ unsigned int x86_feature)
{
- BUILD_BUG_ON(!kvm_is_governed_feature(x86_feature));
+ unsigned int x86_leaf = __feature_leaf(x86_feature);
- return test_bit(kvm_governed_feature_index(x86_feature),
- vcpu->arch.governed_features.enabled);
+ /*
+ * Except for MWAIT, querying dynamic feature bits is disallowed, so
+ * that KVM can defer runtime updates until the next CPUID emulation.
+ */
+ BUILD_BUG_ON(x86_feature == X86_FEATURE_APIC ||
+ x86_feature == X86_FEATURE_OSXSAVE ||
+ x86_feature == X86_FEATURE_OSPKE);
+
+ return vcpu->arch.cpu_caps[x86_leaf] & __feature_bit(x86_feature);
}
static inline bool kvm_vcpu_is_legal_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
{
- if (guest_can_use(vcpu, X86_FEATURE_LAM))
+ if (guest_cpu_cap_has(vcpu, X86_FEATURE_LAM))
cr3 &= ~(X86_CR3_LAM_U48 | X86_CR3_LAM_U57);
return kvm_vcpu_is_legal_gpa(vcpu, cr3);
}
+static inline bool guest_has_spec_ctrl_msr(struct kvm_vcpu *vcpu)
+{
+ return (guest_cpu_cap_has(vcpu, X86_FEATURE_SPEC_CTRL) ||
+ guest_cpu_cap_has(vcpu, X86_FEATURE_AMD_STIBP) ||
+ guest_cpu_cap_has(vcpu, X86_FEATURE_AMD_IBRS) ||
+ guest_cpu_cap_has(vcpu, X86_FEATURE_AMD_SSBD));
+}
+
+static inline bool guest_has_pred_cmd_msr(struct kvm_vcpu *vcpu)
+{
+ return (guest_cpu_cap_has(vcpu, X86_FEATURE_SPEC_CTRL) ||
+ guest_cpu_cap_has(vcpu, X86_FEATURE_AMD_IBPB) ||
+ guest_cpu_cap_has(vcpu, X86_FEATURE_SBPB));
+}
+
#endif
generated by cgit v1.2.3 (git 2.39.0) at 2025-07-09 10:24:36 +0300