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Subject[PATCH v2 19/43] KVM: Add helpers to wake/query blocking vCPU
From
Add helpers to wake and query a blocking vCPU.  In addition to providing
nice names, the helpers reduce the probability of KVM neglecting to use
kvm_arch_vcpu_get_wait().

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/arm64/kvm/arch_timer.c | 3 +--
arch/arm64/kvm/arm.c | 2 +-
arch/x86/kvm/lapic.c | 2 +-
include/linux/kvm_host.h | 14 ++++++++++++++
virt/kvm/async_pf.c | 2 +-
virt/kvm/kvm_main.c | 8 ++------
6 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
index 7e8396f74010..addd53b6eba6 100644
--- a/arch/arm64/kvm/arch_timer.c
+++ b/arch/arm64/kvm/arch_timer.c
@@ -649,7 +649,6 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = vcpu_timer(vcpu);
struct timer_map map;
- struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);

if (unlikely(!timer->enabled))
return;
@@ -672,7 +671,7 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
if (map.emul_ptimer)
soft_timer_cancel(&map.emul_ptimer->hrtimer);

- if (rcuwait_active(wait))
+ if (kvm_vcpu_is_blocking(vcpu))
kvm_timer_blocking(vcpu);

/*
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 268b1e7bf700..9ff0e85a9f16 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -622,7 +622,7 @@ void kvm_arm_resume_guest(struct kvm *kvm)

kvm_for_each_vcpu(i, vcpu, kvm) {
vcpu->arch.pause = false;
- rcuwait_wake_up(kvm_arch_vcpu_get_wait(vcpu));
+ __kvm_vcpu_wake_up(vcpu);
}
}

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 76fb00921203..0cd7ed21b205 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1931,7 +1931,7 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
/* If the preempt notifier has already run, it also called apic_timer_expired */
if (!apic->lapic_timer.hv_timer_in_use)
goto out;
- WARN_ON(rcuwait_active(&vcpu->wait));
+ WARN_ON(kvm_vcpu_is_blocking(vcpu));
apic_timer_expired(apic, false);
cancel_hv_timer(apic);

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bdaa0e70b060..1fa38dc00b87 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1151,6 +1151,20 @@ static inline struct rcuwait *kvm_arch_vcpu_get_wait(struct kvm_vcpu *vcpu)
#endif
}

+/*
+ * Wake a vCPU if necessary, but don't do any stats/metadata updates. Returns
+ * true if the vCPU was blocking and was awakened, false otherwise.
+ */
+static inline bool __kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
+{
+ return !!rcuwait_wake_up(kvm_arch_vcpu_get_wait(vcpu));
+}
+
+static inline bool kvm_vcpu_is_blocking(struct kvm_vcpu *vcpu)
+{
+ return rcuwait_active(kvm_arch_vcpu_get_wait(vcpu));
+}
+
#ifdef __KVM_HAVE_ARCH_INTC_INITIALIZED
/*
* returns true if the virtual interrupt controller is initialized and
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index ccb35c22785e..9bfe1d6f6529 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -85,7 +85,7 @@ static void async_pf_execute(struct work_struct *work)

trace_kvm_async_pf_completed(addr, cr2_or_gpa);

- rcuwait_wake_up(kvm_arch_vcpu_get_wait(vcpu));
+ __kvm_vcpu_wake_up(vcpu);

mmput(mm);
kvm_put_kvm(vcpu->kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 481e8178b43d..c870cae7e776 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3332,10 +3332,7 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_halt);

bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
{
- struct rcuwait *waitp;
-
- waitp = kvm_arch_vcpu_get_wait(vcpu);
- if (rcuwait_wake_up(waitp)) {
+ if (__kvm_vcpu_wake_up(vcpu)) {
WRITE_ONCE(vcpu->ready, true);
++vcpu->stat.generic.halt_wakeup;
return true;
@@ -3490,8 +3487,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
continue;
if (vcpu == me)
continue;
- if (rcuwait_active(kvm_arch_vcpu_get_wait(vcpu)) &&
- !vcpu_dy_runnable(vcpu))
+ if (kvm_vcpu_is_blocking(vcpu) && !vcpu_dy_runnable(vcpu))
continue;
if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
!kvm_arch_dy_has_pending_interrupt(vcpu) &&
--
2.33.0.882.g93a45727a2-goog
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