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KVM: x86: cache maxphyaddr CPUID leaf in struct kvm_vcpu

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cpuid_maxphyaddr(), which performs lot of memory accesses is called
extensively across KVM, especially in nVMX code.

This patch adds a cached value of maxphyaddr to vcpu.arch to reduce the
pressure onto CPU cache and simplify the code of cpuid_maxphyaddr()
callers. The cached value is initialized in kvm_arch_vcpu_init() and
reloaded every time CPUID is updated by usermode. It is obvious that
these reloads occur infrequently.

Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
Message-Id: <20150329205612.GA1223@gnote>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Eugene Korenevsky
2015-03-29 23:56:12 +03:00
committed by Paolo Bonzini
parent 80f0e95d1b
commit 5a4f55cde8
4 changed files with 29 additions and 16 deletions
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6
arch/x86/kvm/cpuid.h
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@@ -20,6 +20,12 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
struct kvm_cpuid_entry2 __user *entries);
void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);
int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu);
static inline int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
{
return vcpu->arch.maxphyaddr;
}
static inline bool guest_cpuid_has_xsave(struct kvm_vcpu *vcpu)
{