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Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Fri,  8 Oct 2021 19:12:12 -0700
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Subject: [PATCH v2 19/43] KVM: Add helpers to wake/query blocking vCPU
From:   Sean Christopherson <seanjc@google.com>
To:     Marc Zyngier <maz@kernel.org>, Huacai Chen <chenhuacai@kernel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
        Paul Mackerras <paulus@ozlabs.org>,
        Anup Patel <anup.patel@wdc.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Cc:     James Morse <james.morse@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Atish Patra <atish.patra@wdc.com>,
        David Hildenbrand <david@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        linux-mips@vger.kernel.org, kvm@vger.kernel.org,
        kvm-ppc@vger.kernel.org, kvm-riscv@lists.infradead.org,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        David Matlack <dmatlack@google.com>,
        Oliver Upton <oupton@google.com>,
        Jing Zhang <jingzhangos@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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