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KVM: nVMX: Wake blocked vCPU in guest-mode if pending interrupt in virtual APICv

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In case L1 do not intercept L2 HLT or enter L2 in HLT activity-state,
it is possible for a vCPU to be blocked while it is in guest-mode.

According to Intel SDM 26.6.5 Interrupt-Window Exiting and
Virtual-Interrupt Delivery: "These events wake the logical processor
if it just entered the HLT state because of a VM entry".
Therefore, if L1 enters L2 in HLT activity-state and L2 has a pending
deliverable interrupt in vmcs12->guest_intr_status.RVI, then the vCPU
should be waken from the HLT state and injected with the interrupt.

In addition, if while the vCPU is blocked (while it is in guest-mode),
it receives a nested posted-interrupt, then the vCPU should also be
waken and injected with the posted interrupt.

To handle these cases, this patch enhances kvm_vcpu_has_events() to also
check if there is a pending interrupt in L2 virtual APICv provided by
L1. That is, it evaluates if there is a pending virtual interrupt for L2
by checking RVI[7:4] > VPPR[7:4] as specified in Intel SDM 29.2.1
Evaluation of Pending Interrupts.

Note that this also handles the case of nested posted-interrupt by the
fact RVI is updated in vmx_complete_nested_posted_interrupt() which is
called from kvm_vcpu_check_block() -> kvm_arch_vcpu_runnable() ->
kvm_vcpu_running() -> vmx_check_nested_events() ->
vmx_complete_nested_posted_interrupt().

Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Liran Alon
2018-09-04 10:56:52 +03:00
committed by Paolo Bonzini
parent 5bea5123cb
commit e6c67d8cf1
3 changed files with 32 additions and 1 deletions
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10
arch/x86/kvm/x86.c
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@@ -9206,6 +9206,13 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
kvm_page_track_flush_slot(kvm, slot);
}
static inline bool kvm_guest_apic_has_interrupt(struct kvm_vcpu *vcpu)
{
return (is_guest_mode(vcpu) &&
kvm_x86_ops->guest_apic_has_interrupt &&
kvm_x86_ops->guest_apic_has_interrupt(vcpu));
}
static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
{
if (!list_empty_careful(&vcpu->async_pf.done))
@@ -9230,7 +9237,8 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
return true;
if (kvm_arch_interrupt_allowed(vcpu) &&
kvm_cpu_has_interrupt(vcpu))
(kvm_cpu_has_interrupt(vcpu) ||
kvm_guest_apic_has_interrupt(vcpu)))
return true;
if (kvm_hv_has_stimer_pending(vcpu))