From: Paul Durrant <pdurrant@xxxxxxxxxx>
Currently when kvm_update_cpuid_runtime() runs, it assumes that the
KVM_CPUID_FEATURES leaf is located at 0x40000001. This is not true,
however, if Hyper-V support is enabled. In this case the KVM leaves will
be offset.
This patch introdues as new 'kvm_cpuid_base' field into struct
kvm_vcpu_arch to track the location of the KVM leaves and function
kvm_update_cpuid_base() (called from kvm_update_cpuid_runtime()) to locate
the leaves using the 'KVMKVMKVM\0\0\0' signature. Adjustment of
KVM_CPUID_FEATURES will hence now target the correct leaf.
Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Cc: Wanpeng Li <wanpengli@xxxxxxxxxxx>
Cc: Jim Mattson <jmattson@xxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/cpuid.c | 50 +++++++++++++++++++++++++++++----
2 files changed, 46 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 88fce6ab4bbd..21133ffa23e9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -725,6 +725,7 @@ struct kvm_vcpu_arch {
int cpuid_nent;
struct kvm_cpuid_entry2 *cpuid_entries;
+ u32 kvm_cpuid_base;
u64 reserved_gpa_bits;
int maxphyaddr;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2d70edb0f323..2cfb8ec4f570 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -99,11 +99,46 @@ static int kvm_check_cpuid(struct kvm_cpuid_entry2 *entries, int nent)
return 0;
}
+static void kvm_update_cpuid_base(struct kvm_vcpu *vcpu)
+{
+ u32 function;
+
+ for (function = 0x40000000; function < 0x40010000; function += 0x100) {
+ struct kvm_cpuid_entry2 *best = kvm_find_cpuid_entry(vcpu, function, 0);
+
+ if (best) {
+ char signature[12];
+
+ *(u32 *)&signature[0] = best->ebx;
+ *(u32 *)&signature[4] = best->ecx;
+ *(u32 *)&signature[8] = best->edx;
+
+ if (!memcmp(signature, "KVMKVMKVM\0\0\0", 12))
+ break;
+ }
+ }
+ vcpu->arch.kvm_cpuid_base = function;
+}
+
+static inline bool kvm_get_cpuid_base(struct kvm_vcpu *vcpu, u32 *function)
+{
+ if (vcpu->arch.kvm_cpuid_base < 0x40000000 ||
+ vcpu->arch.kvm_cpuid_base >= 0x40010000)
+ return false;
+
+ *function = vcpu->arch.kvm_cpuid_base;
+ return true;
+}
+
void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
{
+ u32 base;
struct kvm_cpuid_entry2 *best;
- best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
+ if (!kvm_get_cpuid_base(vcpu, &base))
+ return;
+
+ best = kvm_find_cpuid_entry(vcpu, base + KVM_CPUID_FEATURES, 0);
/*
* save the feature bitmap to avoid cpuid lookup for every PV
@@ -116,6 +151,7 @@ void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
+ u32 base;
best = kvm_find_cpuid_entry(vcpu, 1, 0);
if (best) {
@@ -142,10 +178,14 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
cpuid_entry_has(best, X86_FEATURE_XSAVEC)))
best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
- best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
- if (kvm_hlt_in_guest(vcpu->kvm) && best &&
- (best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
- best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);
+ kvm_update_cpuid_base(vcpu);
+
+ if (kvm_get_cpuid_base(vcpu, &base)) {
+ best = kvm_find_cpuid_entry(vcpu, base + KVM_CPUID_FEATURES, 0);
+ if (kvm_hlt_in_guest(vcpu->kvm) && best &&
+ (best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
+ best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);
+ }
if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT)) {
best = kvm_find_cpuid_entry(vcpu, 0x1, 0);
--
2.20.1
