From 7543a635aa09eb138b2cbf60ac3ff19503ae6954 Mon Sep 17 00:00:00 2001 From: Steve Rutherford Date: Wed, 29 Jul 2015 23:21:41 -0700 Subject: [PATCH] KVM: x86: Add KVM exit for IOAPIC EOIs Adds KVM_EXIT_IOAPIC_EOI which allows the kernel to EOI level-triggered IOAPIC interrupts. Uses a per VCPU exit bitmap to decide whether or not the IOAPIC needs to be informed (which is identical to the EOI_EXIT_BITMAP field used by modern x86 processors, but can also be used to elide kvm IOAPIC EOI exits on older processors). [Note: A prototype using ResampleFDs found that decoupling the EOI from the VCPU's thread made it possible for the VCPU to not see a recent EOI after reentering the guest. This does not match real hardware.] Compile tested for Intel x86. Signed-off-by: Steve Rutherford Signed-off-by: Paolo Bonzini --- Documentation/virtual/kvm/api.txt | 12 ++++++++++++ arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/lapic.c | 24 +++++++++++++++++------- arch/x86/kvm/x86.c | 11 +++++++++++ include/linux/kvm_host.h | 2 +- include/uapi/linux/kvm.h | 5 +++++ 6 files changed, 48 insertions(+), 8 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 43e0816d0de1..0d14bf5db534 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3309,6 +3309,18 @@ Valid values for 'type' are: to ignore the request, or to gather VM memory core dump and/or reset/shutdown of the VM. + /* KVM_EXIT_IOAPIC_EOI */ + struct { + __u8 vector; + } eoi; + +Indicates that the VCPU's in-kernel local APIC received an EOI for a +level-triggered IOAPIC interrupt. This exit only triggers when the +IOAPIC is implemented in userspace (i.e. KVM_CAP_SPLIT_IRQCHIP is enabled); +the userspace IOAPIC should process the EOI and retrigger the interrupt if +it is still asserted. Vector is the LAPIC interrupt vector for which the +EOI was received. + /* Fix the size of the union. */ char padding[256]; }; diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index befcf555bddc..af09fa1d1be7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -574,6 +574,8 @@ struct kvm_vcpu_arch { struct { bool pv_unhalted; } pv; + + int pending_ioapic_eoi; }; struct kvm_lpage_info { diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index e05946c36b87..ef70f6f3a37a 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -877,15 +877,25 @@ static bool kvm_ioapic_handles_vector(struct kvm_lapic *apic, int vector) static void kvm_ioapic_send_eoi(struct kvm_lapic *apic, int vector) { - if (kvm_ioapic_handles_vector(apic, vector)) { - int trigger_mode; - if (apic_test_vector(vector, apic->regs + APIC_TMR)) - trigger_mode = IOAPIC_LEVEL_TRIG; - else - trigger_mode = IOAPIC_EDGE_TRIG; + int trigger_mode; - kvm_ioapic_update_eoi(apic->vcpu, vector, trigger_mode); + /* Eoi the ioapic only if the ioapic doesn't own the vector. */ + if (!kvm_ioapic_handles_vector(apic, vector)) + return; + + /* Request a KVM exit to inform the userspace IOAPIC. */ + if (irqchip_split(apic->vcpu->kvm)) { + apic->vcpu->arch.pending_ioapic_eoi = vector; + kvm_make_request(KVM_REQ_IOAPIC_EOI_EXIT, apic->vcpu); + return; } + + if (apic_test_vector(vector, apic->regs + APIC_TMR)) + trigger_mode = IOAPIC_LEVEL_TRIG; + else + trigger_mode = IOAPIC_EDGE_TRIG; + + kvm_ioapic_update_eoi(apic->vcpu, vector, trigger_mode); } static int apic_set_eoi(struct kvm_lapic *apic) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f720774a4797..27429daa054e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6271,6 +6271,17 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) kvm_pmu_handle_event(vcpu); if (kvm_check_request(KVM_REQ_PMI, vcpu)) kvm_pmu_deliver_pmi(vcpu); + if (kvm_check_request(KVM_REQ_IOAPIC_EOI_EXIT, vcpu)) { + BUG_ON(vcpu->arch.pending_ioapic_eoi > 255); + if (test_bit(vcpu->arch.pending_ioapic_eoi, + (void *) vcpu->arch.eoi_exit_bitmap)) { + vcpu->run->exit_reason = KVM_EXIT_IOAPIC_EOI; + vcpu->run->eoi.vector = + vcpu->arch.pending_ioapic_eoi; + r = 0; + goto out; + } + } if (kvm_check_request(KVM_REQ_SCAN_IOAPIC, vcpu)) vcpu_scan_ioapic(vcpu); if (kvm_check_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu)) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 354f147647ab..3b33215ed447 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -140,6 +140,7 @@ static inline bool is_error_page(struct page *page) #define KVM_REQ_APIC_PAGE_RELOAD 25 #define KVM_REQ_SMI 26 #define KVM_REQ_HV_CRASH 27 +#define KVM_REQ_IOAPIC_EOI_EXIT 28 #define KVM_USERSPACE_IRQ_SOURCE_ID 0 #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1 @@ -1146,4 +1147,3 @@ static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val) } #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ #endif - diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index ed00f8fc9ea2..12e3afbf0f47 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -183,6 +183,7 @@ struct kvm_s390_skeys { #define KVM_EXIT_EPR 23 #define KVM_EXIT_SYSTEM_EVENT 24 #define KVM_EXIT_S390_STSI 25 +#define KVM_EXIT_IOAPIC_EOI 26 /* For KVM_EXIT_INTERNAL_ERROR */ /* Emulate instruction failed. */ @@ -333,6 +334,10 @@ struct kvm_run { __u8 sel1; __u16 sel2; } s390_stsi; + /* KVM_EXIT_IOAPIC_EOI */ + struct { + __u8 vector; + } eoi; /* Fix the size of the union. */ char padding[256]; };