From: David Woodhouse <dwmw@amazon.co.uk>
Date: Tue, 27 Oct 2020 13:55:23 +0000 (+0000)
Subject: kvm/eventfd: Drain events from eventfd in irqfd_wakeup()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b59e00dd8cda75fc8303c9f6847ac720b10664e3;p=linux.git

kvm/eventfd: Drain events from eventfd in irqfd_wakeup()

Don't allow the events to accumulate in the eventfd counter, drain them
as they are handled.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20201027135523.646811-4-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index efa8a5ae7a95f..e996989cd580e 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -194,6 +194,9 @@ irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 	int ret = 0;
 
 	if (flags & EPOLLIN) {
+		u64 cnt;
+		eventfd_ctx_do_read(irqfd->eventfd, &cnt);
+
 		idx = srcu_read_lock(&kvm->irq_srcu);
 		do {
 			seq = read_seqcount_begin(&irqfd->irq_entry_sc);