linux-kernel - [PATCH 1/5] KVM: Extract the irqfd_wakeup_pollin/irqfd_wakeup

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Date:	Thu,  3 Dec 2015 10:22:48 -0800
From:	Yunhong Jiang <yunhong.jiang@...ux.intel.com>
To:	alex.williamson@...hat.com, pbonzini@...hat.com
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/5] KVM: Extract the irqfd_wakeup_pollin/irqfd_wakeup_pollup

Separate the irqfd_wakeup_pollin/irqfd_wakeup_pollup from the
irqfd_wakeup, so that we can reuse the logic for MSI fastpath injection.

Signed-off-by: Yunhong Jiang <yunhong.jiang@...ux.intel.com>
---
 virt/kvm/eventfd.c | 86 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 51 insertions(+), 35 deletions(-)

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 46dbc0a7dfc1..c31d43b762db 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -180,6 +180,53 @@ int __attribute__((weak)) kvm_arch_set_irq_inatomic(
 	return -EWOULDBLOCK;
 }
 
+static int
+irqfd_wakeup_pollin(struct kvm_kernel_irqfd *irqfd)
+{
+	struct kvm *kvm = irqfd->kvm;
+	struct kvm_kernel_irq_routing_entry irq;
+	unsigned seq;
+	int idx, ret;
+
+	idx = srcu_read_lock(&kvm->irq_srcu);
+	do {
+		seq = read_seqcount_begin(&irqfd->irq_entry_sc);
+		irq = irqfd->irq_entry;
+	} while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
+	/* An event has been signaled, inject an interrupt */
+	ret = kvm_arch_set_irq_inatomic(&irq, kvm,
+				KVM_USERSPACE_IRQ_SOURCE_ID, 1,
+				false);
+	srcu_read_unlock(&kvm->irq_srcu, idx);
+
+	return ret;
+}
+
+static int
+irqfd_wakeup_pollup(struct kvm_kernel_irqfd *irqfd)
+{
+	struct kvm *kvm = irqfd->kvm;
+	unsigned long flags;
+
+	spin_lock_irqsave(&kvm->irqfds.lock, flags);
+
+	/*
+	 * We must check if someone deactivated the irqfd before
+	 * we could acquire the irqfds.lock since the item is
+	 * deactivated from the KVM side before it is unhooked from
+	 * the wait-queue.  If it is already deactivated, we can
+	 * simply return knowing the other side will cleanup for us.
+	 * We cannot race against the irqfd going away since the
+	 * other side is required to acquire wqh->lock, which we hold
+	 */
+	if (irqfd_is_active(irqfd))
+		irqfd_deactivate(irqfd);
+
+	spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
+
+	return 0;
+}
+
 /*
  * Called with wqh->lock held and interrupts disabled
  */
@@ -189,45 +236,14 @@ irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
 	struct kvm_kernel_irqfd *irqfd =
 		container_of(wait, struct kvm_kernel_irqfd, wait);
 	unsigned long flags = (unsigned long)key;
-	struct kvm_kernel_irq_routing_entry irq;
-	struct kvm *kvm = irqfd->kvm;
-	unsigned seq;
-	int idx;
 
-	if (flags & POLLIN) {
-		idx = srcu_read_lock(&kvm->irq_srcu);
-		do {
-			seq = read_seqcount_begin(&irqfd->irq_entry_sc);
-			irq = irqfd->irq_entry;
-		} while (read_seqcount_retry(&irqfd->irq_entry_sc, seq));
-		/* An event has been signaled, inject an interrupt */
-		if (kvm_arch_set_irq_inatomic(&irq, kvm,
-					      KVM_USERSPACE_IRQ_SOURCE_ID, 1,
-					      false) == -EWOULDBLOCK)
+	if (flags & POLLIN)
+		if (irqfd_wakeup_pollin(irqfd) == -EWOULDBLOCK)
 			schedule_work(&irqfd->inject);
-		srcu_read_unlock(&kvm->irq_srcu, idx);
-	}
 
-	if (flags & POLLHUP) {
+	if (flags & POLLHUP)
 		/* The eventfd is closing, detach from KVM */
-		unsigned long flags;
-
-		spin_lock_irqsave(&kvm->irqfds.lock, flags);
-
-		/*
-		 * We must check if someone deactivated the irqfd before
-		 * we could acquire the irqfds.lock since the item is
-		 * deactivated from the KVM side before it is unhooked from
-		 * the wait-queue.  If it is already deactivated, we can
-		 * simply return knowing the other side will cleanup for us.
-		 * We cannot race against the irqfd going away since the
-		 * other side is required to acquire wqh->lock, which we hold
-		 */
-		if (irqfd_is_active(irqfd))
-			irqfd_deactivate(irqfd);
-
-		spin_unlock_irqrestore(&kvm->irqfds.lock, flags);
-	}
+		irqfd_wakeup_pollup(irqfd);
 
 	return 0;
 }
-- 
1.8.3.1

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