If L1 doesn't intercept L2 HLT (doesn't set CPU_BASED_HLT_EXITING),
then when L2 executes HLT instruction, KVM will block vCPU from
further execution (just like what happens when L1 executes HLT).
Consider the case where vmx_deliver_nested_posted_interrupt() sees
that vcpu->mode == IN_GUEST_MODE and therefore sends a physical IPI.
Assume that before it sends the physical IPI, the dest CPU executing
L2 executes HLT which causes the dest vCPU to be blocked.
Before the dest vCPU is blocked, a call to kvm_arch_vcpu_runnable()
is made which calls kvm_vcpu_has_events(). In addition, after the
vCPU is blocked, every time it is interrupted (by IPI) then
kvm_vcpu_check_block() is called which also calls
kvm_arch_vcpu_runnable().
kvm_vcpu_has_events() should return if there is a pending event for
vCPU that should be processed and therefore vCPU should be unblocked.
In order to handle the above mentioned case, kvm_vcpu_has_events()
should check if there is a pending nested posted-interrupt on vCPU
that should be dispatched to guest.
Fixes: 705699a13994 ("KVM: nVMX: Enable nested posted interrupt
processing")
Signed-off-by: Liran Alon <liran.alon@xxxxxxxxxx>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@xxxxxxxxxx>
Reviewed-by: Liam Merwick <liam.merwick@xxxxxxxxxx>
Signed-off-by: Liam Merwick <liam.merwick@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 7 +++++++
arch/x86/kvm/vmx.c | 13 +++++++++++++
arch/x86/kvm/x86.c | 3 ++-
4 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4b8caff83dc7..71c240bbb685 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -994,6 +994,7 @@ struct kvm_x86_ops {
void (*set_apic_access_page_addr)(struct kvm_vcpu *vcpu, hpa_t hpa);
void (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
void (*complete_nested_posted_interrupt)(struct kvm_vcpu *vcpu);
+ bool (*cpu_has_nested_posted_interrupt)(struct kvm_vcpu *vcpu);
int (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
int (*get_tdp_level)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 183f7aec29ca..a559c26d7bff 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4458,6 +4458,11 @@ static void svm_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
{
}
+static bool svm_cpu_has_nested_posted_interrupt(struct kvm_vcpu *vcpu)
+{
+ return false;
+}
+
/* Note: Currently only used by Hyper-V. */
static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
{
@@ -5593,6 +5598,8 @@ static int enable_smi_window(struct kvm_vcpu *vcpu)
.sync_pir_to_irr = svm_sync_pir_to_irr,
.complete_nested_posted_interrupt =
svm_complete_nested_posted_interrupt,
+ .cpu_has_nested_posted_interrupt =
+ svm_cpu_has_nested_posted_interrupt,
.apicv_post_state_restore = avic_post_state_restore,
.set_tss_addr = svm_set_tss_addr,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c2d012d9d16d..8b414dd5e07c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5141,6 +5141,17 @@ static void vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
}
}
+static bool vmx_cpu_has_nested_posted_interrupt(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ return (vcpu->arch.apicv_active &&
+ is_guest_mode(vcpu) &&
+ vmx->nested.pi_pending &&
+ vmx->nested.pi_desc &&
+ pi_test_on(vmx->nested.pi_desc));
+}
+
/*
* Set up the vmcs's constant host-state fields, i.e., host-state fields that
* will not change in the lifetime of the guest.
@@ -12142,6 +12153,8 @@ static int enable_smi_window(struct kvm_vcpu *vcpu)
.deliver_posted_interrupt = vmx_deliver_posted_interrupt,
.complete_nested_posted_interrupt =
vmx_complete_nested_posted_interrupt,
+ .cpu_has_nested_posted_interrupt =
+ vmx_cpu_has_nested_posted_interrupt,
.set_tss_addr = vmx_set_tss_addr,
.get_tdp_level = get_ept_level,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fa088951afc9..a840f2c9bd66 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8542,7 +8542,8 @@ 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_x86_ops->cpu_has_nested_posted_interrupt(vcpu)))
return true;
if (kvm_hv_has_stimer_pending(vcpu))
--
1.9.1
