From ae7a2a3fb6f8b784c2752863f4f1f20c656f76fb Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 24 Jun 2012 19:25:07 +0300 Subject: KVM: host side for eoi optimization Implementation of PV EOI using shared memory. This reduces the number of exits an interrupt causes as much as by half. The idea is simple: there's a bit, per APIC, in guest memory, that tells the guest that it does not need EOI. We set it before injecting an interrupt and clear before injecting a nested one. Guest tests it using a test and clear operation - this is necessary so that host can detect interrupt nesting - and if set, it can skip the EOI MSR. There's a new MSR to set the address of said register in guest memory. Otherwise not much changed: - Guest EOI is not required - Register is tested & ISR is automatically cleared on exit For testing results see description of previous patch 'kvm_para: guest side for eoi avoidance'. Signed-off-by: Michael S. Tsirkin Signed-off-by: Avi Kivity --- arch/x86/kvm/x86.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ea0f611bc89..8eacb2e64560 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -795,6 +795,7 @@ static u32 msrs_to_save[] = { MSR_KVM_SYSTEM_TIME_NEW, MSR_KVM_WALL_CLOCK_NEW, HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL, HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME, + MSR_KVM_PV_EOI_EN, MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP, MSR_STAR, #ifdef CONFIG_X86_64 @@ -1653,6 +1654,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu); break; + case MSR_KVM_PV_EOI_EN: + if (kvm_lapic_enable_pv_eoi(vcpu, data)) + return 1; + break; case MSR_IA32_MCG_CTL: case MSR_IA32_MCG_STATUS: @@ -5394,6 +5399,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) cancel_injection: kvm_x86_ops->cancel_injection(vcpu); + if (unlikely(vcpu->arch.apic_attention)) + kvm_lapic_sync_from_vapic(vcpu); out: return r; } -- cgit v1.2.3