[PATCH v3 2/9] KVM: x86: Move pv_unhaulted check out of kvm_vcpu_has_events()
From: Binbin Wu
Date: Fri Feb 21 2025 - 20:41:49 EST
Move pv_unhaulted check out of kvm_vcpu_has_events(), check pv_unhaulted
explicitly when handling PV unhalt and expose kvm_vcpu_has_events().
kvm_vcpu_has_events() returns true if pv_unhalted is set, and pv_unhalted
is only cleared on transitions to KVM_MP_STATE_RUNNABLE. If the guest
initiates a spurious wakeup, pv_unhalted could be left set in perpetuity.
Currently, this is not problematic because kvm_vcpu_has_events() is only
called when handling PV unhalt. However, if kvm_vcpu_has_events() is used
for other purposes in the future, it could return the unexpected results.
Export kvm_vcpu_has_events() for its usage in broader contexts.
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
---
Hypercalls exit to userspace v3:
- New added.
---
arch/x86/kvm/x86.c | 11 +++++------
include/linux/kvm_host.h | 1 +
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 62dded70932d..8877d6db9b84 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11133,7 +11133,7 @@ static bool kvm_vcpu_running(struct kvm_vcpu *vcpu)
!vcpu->arch.apf.halted);
}
-static bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
+bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
{
if (!list_empty_careful(&vcpu->async_pf.done))
return true;
@@ -11142,9 +11142,6 @@ static bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
kvm_apic_init_sipi_allowed(vcpu))
return true;
- if (vcpu->arch.pv.pv_unhalted)
- return true;
-
if (kvm_is_exception_pending(vcpu))
return true;
@@ -11182,10 +11179,12 @@ static bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
return false;
}
+EXPORT_SYMBOL_GPL(kvm_vcpu_has_events);
int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
{
- return kvm_vcpu_running(vcpu) || kvm_vcpu_has_events(vcpu);
+ return kvm_vcpu_running(vcpu) || vcpu->arch.pv.pv_unhalted ||
+ kvm_vcpu_has_events(vcpu);
}
/* Called within kvm->srcu read side. */
@@ -11321,7 +11320,7 @@ static int __kvm_emulate_halt(struct kvm_vcpu *vcpu, int state, int reason)
*/
++vcpu->stat.halt_exits;
if (lapic_in_kernel(vcpu)) {
- if (kvm_vcpu_has_events(vcpu))
+ if (kvm_vcpu_has_events(vcpu) || vcpu->arch.pv.pv_unhalted)
vcpu->arch.pv.pv_unhalted = false;
else
vcpu->arch.mp_state = state;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3bfe3140f444..ed1968f6f841 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1609,6 +1609,7 @@ void kvm_arch_disable_virtualization(void);
int kvm_arch_enable_virtualization_cpu(void);
void kvm_arch_disable_virtualization_cpu(void);
#endif
+bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu);
int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu);
bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu);
int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);
--
2.46.0