On 27/02/2025 7:14 am, Paolo Bonzini wrote:
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx>
... assuming there will be a changelog, e.g., perhaps something like below:
TDX will need to search a CPUID leaf from a list of per-TD scope CPUID
entries w/o any vCPU context. Abstract the code which does CPUID entry
search from a given list of CPUID entries as kvm_find_cpuid_entry2() and
Export it for TDX to use.
And one nit below ...
@@ -141,23 +141,26 @@ static struct kvm_cpuid_entry2 *cpuid_entry2_find(struct kvm_vcpu *vcpu,
return NULL;
}
+EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry2);
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry_index(struct kvm_vcpu *vcpu,
u32 function, u32 index)
{
- return cpuid_entry2_find(vcpu, function, index);
+ return kvm_find_cpuid_entry2(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,
+ function, index);
}
EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry_index);
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
u32 function)
{
- return cpuid_entry2_find(vcpu, function, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
+ return kvm_find_cpuid_entry2(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,
+ function, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
}
EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
... I think we can change both kvm_find_cpuid_entry_index() and
kvm_find_cpuid_entry() to 'static inline' and place them in the
kvm/cpuid.h to avoid exporting them.
See attached diff. Build test only.
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7ff84079c1f4..ecf2750693d4 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -143,22 +143,6 @@ struct kvm_cpuid_entry2 *kvm_find_cpuid_entry2(
}
EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry2);
-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);
-}
-EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry_index);
-
-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);
-}
-EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
-
/*
* kvm_find_cpuid_entry2() and KVM_CPUID_INDEX_NOT_SIGNIFICANT should never be used
* directly outside of kvm_find_cpuid_entry() and kvm_find_cpuid_entry_index().
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 46e059b47825..738b396416cd 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -14,10 +14,29 @@ void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu);
void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu);
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry2(struct kvm_cpuid_entry2 *entries,
int nent, u32 function, u64 index);
-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);
+/*
+ * 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.
+ */
+#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);
