[RFC PATCH v3 29/59] KVM: x86: Add option to force LAPIC expiration wait

isaku.yamahata
2021-11-25T00:21:43Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

Add an option to skip the IRR check in kvm_wait_lapic_expire(). This
will be used by TDX to wait if there is an outstanding notification for
a TD, i.e. a virtual interrupt is being triggered via posted interrupt
processing. KVM TDX doesn't emulate PI processing, i.e. there will
never be a bit set in IRR/ISR, so the default behavior for APICv of
querying the IRR doesn't work as intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/lapic.c | 4 ++--
arch/x86/kvm/lapic.h | 2 +-
arch/x86/kvm/svm/svm.c | 2 +-
arch/x86/kvm/vmx/vmx.c | 2 +-
4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 1bfcd325d0d2..beef195b9d15 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1625,12 +1625,12 @@ static void __kvm_wait_lapic_expire(struct kvm_vcpu *vcpu)
__wait_lapic_expire(vcpu, tsc_deadline - guest_tsc);
}

-void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu)
+void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu, bool force_wait)
{
if (lapic_in_kernel(vcpu) &&
vcpu->arch.apic->lapic_timer.expired_tscdeadline &&
vcpu->arch.apic->lapic_timer.timer_advance_ns &&
- lapic_timer_int_injected(vcpu))
+ (force_wait || lapic_timer_int_injected(vcpu)))
__kvm_wait_lapic_expire(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_wait_lapic_expire);
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 2b44e533fc8d..2a0119ef9e96 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -233,7 +233,7 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu)

bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);

-void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu);
+void kvm_wait_lapic_expire(struct kvm_vcpu *vcpu, bool force_wait);

void kvm_bitmap_or_dest_vcpus(struct kvm *kvm, struct kvm_lapic_irq *irq,
unsigned long *vcpu_bitmap);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 1bf410add13b..e33cbf9613d9 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3885,7 +3885,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
clgi();
kvm_load_guest_xsave_state(vcpu);

- kvm_wait_lapic_expire(vcpu);
+ kvm_wait_lapic_expire(vcpu, false);

/*
* If this vCPU has touched SPEC_CTRL, restore the guest's value if
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 5e4c6ac9fe69..1e20e85a958f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6647,7 +6647,7 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (enable_preemption_timer)
vmx_update_hv_timer(vcpu);

- kvm_wait_lapic_expire(vcpu);
+ kvm_wait_lapic_expire(vcpu, false);

/*
* If this vCPU has touched SPEC_CTRL, restore the guest's value if
--
2.25.1