[PATCH RFC 2/2] KVM: x86: use general helpers for some cpuid manipulation

Radim Krčmář
2017-08-02T20:43:26Z

Add guest_cpuid_clear() and use it instead of kvm_find_cpuid_entry().
Also replace some uses of kvm_find_cpuid_entry() with guest_cpuid_has().

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/kvm/cpuid.h | 9 +++++++++
arch/x86/kvm/svm.c | 5 +----
arch/x86/kvm/vmx.c | 9 +++------
arch/x86/kvm/x86.c | 14 ++------------
4 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 3b17d915b608..650b5c80c5a0 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -104,6 +104,15 @@ static inline bool guest_cpuid_has(struct kvm_vcpu *vcpu, unsigned x86_feature)
return *reg & bit(x86_feature);
}

+static inline void guest_cpuid_clear(struct kvm_vcpu *vcpu, unsigned x86_feature)
+{
+ int *reg;
+
+ reg = guest_cpuid_get_register(vcpu, x86_feature);
+ if (reg)
+ *reg &= ~bit(x86_feature);
+}
+
static inline bool guest_cpuid_is_amd(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index fcdc1412792e..5ceb99ff145b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5065,7 +5065,6 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
static void svm_cpuid_update(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
- struct kvm_cpuid_entry2 *entry;

/* Update nrips enabled cache */
svm->nrips_enabled = !!guest_cpuid_has(&svm->vcpu, X86_FEATURE_NRIPS);
@@ -5073,9 +5072,7 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
if (!kvm_vcpu_apicv_active(vcpu))
return;

- entry = kvm_find_cpuid_entry(vcpu, 1, 0);
- if (entry)
- entry->ecx &= ~bit(X86_FEATURE_X2APIC);
+ guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);
}

static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 8367f901d681..e34373838b31 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9376,7 +9376,6 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)

static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
{
- struct kvm_cpuid_entry2 *best;
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 secondary_exec_ctl = vmx_secondary_exec_control(vmx);

@@ -9396,14 +9395,12 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
}

/* Exposing INVPCID only when PCID is exposed */
- best = kvm_find_cpuid_entry(vcpu, 0x7, 0);
if (vmx_invpcid_supported() &&
- (!best || !(best->ebx & bit(X86_FEATURE_INVPCID)) ||
- !guest_cpuid_has(vcpu, X86_FEATURE_PCID))) {
+ (!guest_cpuid_has(vcpu, X86_FEATURE_INVPCID) ||
+ !guest_cpuid_has(vcpu, X86_FEATURE_PCID))) {
secondary_exec_ctl &= ~SECONDARY_EXEC_ENABLE_INVPCID;

- if (best)
- best->ebx &= ~bit(X86_FEATURE_INVPCID);
+ guest_cpuid_clear(vcpu, X86_FEATURE_INVPCID);
}

if (cpu_has_secondary_exec_ctrls())
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d75997ba65b9..9bba971fb51e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1021,21 +1021,11 @@ bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
if (efer & efer_reserved_bits)
return false;

- if (efer & EFER_FFXSR) {
- struct kvm_cpuid_entry2 *feat;
-
- feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
- if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
+ if (efer & EFER_FFXSR && !guest_cpuid_has(vcpu, X86_FEATURE_FXSR_OPT))
return false;
- }

- if (efer & EFER_SVME) {
- struct kvm_cpuid_entry2 *feat;
-
- feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
- if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
+ if (efer & EFER_SVME && !guest_cpuid_has(vcpu, X86_FEATURE_SVM))
return false;
- }

return true;
}
--
2.13.3