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authorSteve Rutherford <srutherford@google.com>2015-07-29 23:21:41 -0700
committerPaolo Bonzini <pbonzini@redhat.com>2015-10-01 15:06:27 +0200
commit7543a635aa09eb138b2cbf60ac3ff19503ae6954 (patch)
tree94d181962c2a3f64019f182900ed216a2f0c3e73
parent49df6397edfc5a8ba8ca813b51fb9729d8e94b40 (diff)
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 <srutherford@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--Documentation/virtual/kvm/api.txt12
-rw-r--r--arch/x86/include/asm/kvm_host.h2
-rw-r--r--arch/x86/kvm/lapic.c24
-rw-r--r--arch/x86/kvm/x86.c11
-rw-r--r--include/linux/kvm_host.h2
-rw-r--r--include/uapi/linux/kvm.h5
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;
+
+ /* Eoi the ioapic only if the ioapic doesn't own the vector. */
+ if (!kvm_ioapic_handles_vector(apic, vector))
+ return;
- kvm_ioapic_update_eoi(apic->vcpu, vector, trigger_mode);
+ /* 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];
};