[PATCH v2 02/26] KVM: Split cpuid register access from computation

Avi Kivity
2012-06-27T15:19:38Z

Introduce kvm_cpuid() to perform the leaf limit check and calculate
register values, and let kvm_emulate_cpuid() just handle reading and
writing the registers from/to the vcpu. This allows us to reuse
kvm_cpuid() in a context where directly reading and writing registers
is not desired.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/cpuid.c | 38 ++++++++++++++++++++++++--------------
arch/x86/kvm/cpuid.h | 1 +
2 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7df1c6d..44476fb 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -639,33 +639,43 @@ static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
}

-void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
+void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
{
- u32 function, index;
+ u32 function = *eax, index = *ecx;
struct kvm_cpuid_entry2 *best;

- function = kvm_register_read(vcpu, VCPU_REGS_RAX);
- index = kvm_register_read(vcpu, VCPU_REGS_RCX);
- kvm_register_write(vcpu, VCPU_REGS_RAX, 0);
- kvm_register_write(vcpu, VCPU_REGS_RBX, 0);
- kvm_register_write(vcpu, VCPU_REGS_RCX, 0);
- kvm_register_write(vcpu, VCPU_REGS_RDX, 0);
best = kvm_find_cpuid_entry(vcpu, function, index);

if (!best)
best = check_cpuid_limit(vcpu, function, index);

if (best) {
- kvm_register_write(vcpu, VCPU_REGS_RAX, best->eax);
- kvm_register_write(vcpu, VCPU_REGS_RBX, best->ebx);
- kvm_register_write(vcpu, VCPU_REGS_RCX, best->ecx);
- kvm_register_write(vcpu, VCPU_REGS_RDX, best->edx);
- }
- kvm_x86_ops->skip_emulated_instruction(vcpu);
+ *eax = best->eax;
+ *ebx = best->ebx;
+ *ecx = best->ecx;
+ *edx = best->edx;
+ } else
+ *eax = *ebx = *ecx = *edx = 0;
+
trace_kvm_cpuid(function,
kvm_register_read(vcpu, VCPU_REGS_RAX),
kvm_register_read(vcpu, VCPU_REGS_RBX),
kvm_register_read(vcpu, VCPU_REGS_RCX),
kvm_register_read(vcpu, VCPU_REGS_RDX));
}
+
+void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
+{
+ u32 function, eax, ebx, ecx, edx;
+
+ function = eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
+ ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
+ kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx);
+ kvm_register_write(vcpu, VCPU_REGS_RAX, eax);
+ kvm_register_write(vcpu, VCPU_REGS_RBX, ebx);
+ kvm_register_write(vcpu, VCPU_REGS_RCX, ecx);
+ kvm_register_write(vcpu, VCPU_REGS_RDX, edx);
+ kvm_x86_ops->skip_emulated_instruction(vcpu);
+ trace_kvm_cpuid(function, eax, ebx, ecx, edx);
+}
EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 26d1fb4..f449edc 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -17,6 +17,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 __user *entries);
+void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);

static inline bool guest_cpuid_has_xsave(struct kvm_vcpu *vcpu)
--
1.7.11