KVM: x86: use static calls to reduce kvm_x86_ops overhead
Convert kvm_x86_ops to use static calls. Note that all kvm_x86_ops are
covered here except for 'pmu_ops and 'nested ops'.
Here are some numbers running cpuid in a loop of 1 million calls averaged
over 5 runs, measured in the vm (lower is better).
Intel Xeon 3000MHz:
|default |mitigations=off
-------------------------------------
vanilla |.671s |.486s
static call|.573s(-15%)|.458s(-6%)
AMD EPYC 2500MHz:
|default |mitigations=off
-------------------------------------
vanilla |.710s |.609s
static call|.664s(-6%) |.609s(0%)
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Message-Id: <e057bf1b8a7ad15652df6eeba3f907ae758d3399.1610680941.git.jbaron@akamai.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 2bb42ee..c68bfc3 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -102,7 +102,7 @@ static inline void kvm_mmu_load_pgd(struct kvm_vcpu *vcpu)
if (!VALID_PAGE(root_hpa))
return;
- kvm_x86_ops.load_mmu_pgd(vcpu, root_hpa | kvm_get_active_pcid(vcpu),
+ static_call(kvm_x86_load_mmu_pgd)(vcpu, root_hpa | kvm_get_active_pcid(vcpu),
vcpu->arch.mmu->shadow_root_level);
}
@@ -174,8 +174,8 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
unsigned pte_access, unsigned pte_pkey,
unsigned pfec)
{
- int cpl = kvm_x86_ops.get_cpl(vcpu);
- unsigned long rflags = kvm_x86_ops.get_rflags(vcpu);
+ int cpl = static_call(kvm_x86_get_cpl)(vcpu);
+ unsigned long rflags = static_call(kvm_x86_get_rflags)(vcpu);
/*
* If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1.