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KVM: x86: optimize check for valid PAT value 

This check will soon be done on every nested vmentry and vmexit,
"parallelize" it using bitwise operations.

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2019-04-10 11:41:40 +02:00
parent f16cb57be8
commit 674ea351cd
3 changed files with 12 additions and 10 deletions
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10
arch/x86/kvm/mtrr.c
View File

@ -48,11 +48,6 @@ static bool msr_mtrr_valid(unsigned msr)
return false;
}
static bool valid_pat_type(unsigned t)
{
return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
}
static bool valid_mtrr_type(unsigned t)
{
return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
@ -67,10 +62,7 @@ bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
return false;
if (msr == MSR_IA32_CR_PAT) {
for (i = 0; i < 8; i++)
if (!valid_pat_type((data >> (i * 8)) & 0xff))
return false;
return true;
return kvm_pat_valid(data);
} else if (msr == MSR_MTRRdefType) {
if (data & ~0xcff)
return false;

2
arch/x86/kvm/vmx/vmx.c
View File

@ -1891,7 +1891,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
break;
case MSR_IA32_CR_PAT:
if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
if (!kvm_pat_valid(data))
return 1;
vmcs_write64(GUEST_IA32_PAT, data);
vcpu->arch.pat = data;

10
arch/x86/kvm/x86.h
View File

@ -347,6 +347,16 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
__this_cpu_write(current_vcpu, NULL);
}
static inline bool kvm_pat_valid(u64 data)
{
if (data & 0xF8F8F8F8F8F8F8F8ull)
return false;
/* 0, 1, 4, 5, 6, 7 are valid values. */
return (data | ((data & 0x0202020202020202ull) << 1)) == data;
}
void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu);
void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu);
#endif