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authorWanpeng Li <wanpeng.li@linux.intel.com>2014-08-05 12:42:24 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2014-08-05 15:00:24 +0200
commit56cc2406d68c0f09505c389e276f27a99f495cbd (patch)
tree90e2d04ea45d9a22023ca6371dfc878cf4b70c2e /arch/x86/kvm
parentf3380ca5d7edb5e31932998ab2e29dfdce39c5ed (diff)
downloadlinux-56cc2406d68c0f09505c389e276f27a99f495cbd.tar.gz
KVM: nVMX: fix "acknowledge interrupt on exit" when APICv is in use
After commit 77b0f5d (KVM: nVMX: Ack and write vector info to intr_info if L1 asks us to), "Acknowledge interrupt on exit" behavior can be emulated. To do so, KVM will ask the APIC for the interrupt vector if during a nested vmexit if VM_EXIT_ACK_INTR_ON_EXIT is set. With APICv, kvm_get_apic_interrupt would return -1 and give the following WARNING: Call Trace: [<ffffffff81493563>] dump_stack+0x49/0x5e [<ffffffff8103f0eb>] warn_slowpath_common+0x7c/0x96 [<ffffffffa059709a>] ? nested_vmx_vmexit+0xa4/0x233 [kvm_intel] [<ffffffff8103f11a>] warn_slowpath_null+0x15/0x17 [<ffffffffa059709a>] nested_vmx_vmexit+0xa4/0x233 [kvm_intel] [<ffffffffa0594295>] ? nested_vmx_exit_handled+0x6a/0x39e [kvm_intel] [<ffffffffa0537931>] ? kvm_apic_has_interrupt+0x80/0xd5 [kvm] [<ffffffffa05972ec>] vmx_check_nested_events+0xc3/0xd3 [kvm_intel] [<ffffffffa051ebe9>] inject_pending_event+0xd0/0x16e [kvm] [<ffffffffa051efa0>] vcpu_enter_guest+0x319/0x704 [kvm] To fix this, we cannot rely on the processor's virtual interrupt delivery, because "acknowledge interrupt on exit" must only update the virtual ISR/PPR/IRR registers (and SVI, which is just a cache of the virtual ISR) but it should not deliver the interrupt through the IDT. Thus, KVM has to deliver the interrupt "by hand", similar to the treatment of EOI in commit fc57ac2c9ca8 (KVM: lapic: sync highest ISR to hardware apic on EOI, 2014-05-14). The patch modifies kvm_cpu_get_interrupt to always acknowledge an interrupt; there are only two callers, and the other is not affected because it is never reached with kvm_apic_vid_enabled() == true. Then it modifies apic_set_isr and apic_clear_irr to update SVI and RVI in addition to the registers. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Suggested-by: "Zhang, Yang Z" <yang.z.zhang@intel.com> Tested-by: Liu, RongrongX <rongrongx.liu@intel.com> Tested-by: Felipe Reyes <freyes@suse.com> Fixes: 77b0f5d67ff2781f36831cba79674c3e97bd7acf Cc: stable@vger.kernel.org Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/irq.c2
-rw-r--r--arch/x86/kvm/lapic.c52
2 files changed, 40 insertions, 14 deletions
diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
index bd0da433e6d..a1ec6a50a05 100644
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -108,7 +108,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
vector = kvm_cpu_get_extint(v);
- if (kvm_apic_vid_enabled(v->kvm) || vector != -1)
+ if (vector != -1)
return vector; /* PIC */
return kvm_get_apic_interrupt(v); /* APIC */
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 3855103f71f..08e8a899e00 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -352,25 +352,46 @@ static inline int apic_find_highest_irr(struct kvm_lapic *apic)
static inline void apic_clear_irr(int vec, struct kvm_lapic *apic)
{
- apic->irr_pending = false;
+ struct kvm_vcpu *vcpu;
+
+ vcpu = apic->vcpu;
+
apic_clear_vector(vec, apic->regs + APIC_IRR);
- if (apic_search_irr(apic) != -1)
- apic->irr_pending = true;
+ if (unlikely(kvm_apic_vid_enabled(vcpu->kvm)))
+ /* try to update RVI */
+ kvm_make_request(KVM_REQ_EVENT, vcpu);
+ else {
+ vec = apic_search_irr(apic);
+ apic->irr_pending = (vec != -1);
+ }
}
static inline void apic_set_isr(int vec, struct kvm_lapic *apic)
{
- /* Note that we never get here with APIC virtualization enabled. */
+ struct kvm_vcpu *vcpu;
+
+ if (__apic_test_and_set_vector(vec, apic->regs + APIC_ISR))
+ return;
+
+ vcpu = apic->vcpu;
- if (!__apic_test_and_set_vector(vec, apic->regs + APIC_ISR))
- ++apic->isr_count;
- BUG_ON(apic->isr_count > MAX_APIC_VECTOR);
/*
- * ISR (in service register) bit is set when injecting an interrupt.
- * The highest vector is injected. Thus the latest bit set matches
- * the highest bit in ISR.
+ * With APIC virtualization enabled, all caching is disabled
+ * because the processor can modify ISR under the hood. Instead
+ * just set SVI.
*/
- apic->highest_isr_cache = vec;
+ if (unlikely(kvm_apic_vid_enabled(vcpu->kvm)))
+ kvm_x86_ops->hwapic_isr_update(vcpu->kvm, vec);
+ else {
+ ++apic->isr_count;
+ BUG_ON(apic->isr_count > MAX_APIC_VECTOR);
+ /*
+ * ISR (in service register) bit is set when injecting an interrupt.
+ * The highest vector is injected. Thus the latest bit set matches
+ * the highest bit in ISR.
+ */
+ apic->highest_isr_cache = vec;
+ }
}
static inline int apic_find_highest_isr(struct kvm_lapic *apic)
@@ -1627,11 +1648,16 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
int vector = kvm_apic_has_interrupt(vcpu);
struct kvm_lapic *apic = vcpu->arch.apic;
- /* Note that we never get here with APIC virtualization enabled. */
-
if (vector == -1)
return -1;
+ /*
+ * We get here even with APIC virtualization enabled, if doing
+ * nested virtualization and L1 runs with the "acknowledge interrupt
+ * on exit" mode. Then we cannot inject the interrupt via RVI,
+ * because the process would deliver it through the IDT.
+ */
+
apic_set_isr(vector, apic);
apic_update_ppr(apic);
apic_clear_irr(vector, apic);