From: David Woodhouse <dwmw2@infradead.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org
Subject: [PATCH v2 0/2] Allow KVM IRQFD to consistently intercept events
Date: Tue, 27 Oct 2020 14:39:42 +0000 [thread overview]
Message-ID: <20201027143944.648769-1-dwmw2@infradead.org> (raw)
In-Reply-To: <20201026175325.585623-1-dwmw2@infradead.org>
When posted interrupts are in use, KVM fully bypasses the eventfd and
delivers events directly to the appropriate vCPU. Without posted
interrupts, it still uses the eventfd but it doesn't actually stop
userspace from receiving the events too. This leaves userspace having
to carefully avoid seeing the same events and injecting duplicate
interrupts to the guest.
Fix it by adding a 'priority' mode for exclusive waiters which puts them
at the head of the list, where they can consume events before the
non-exclusive waiters are woken.
v2:
• Drop [RFC]. This seems to be working nicely, and userspace is a lot
cleaner without having to mess around with adding/removing the eventfd
to its poll set. And nobody yelled at me. Yet.
• Reword commit comments, update comment above __wake_up_common()
• Rebase to be applied after the (only vaguely related) fix to make
irqfd actually consume the eventfd counter too.
David Woodhouse (2):
sched/wait: Add add_wait_queue_priority()
kvm/eventfd: Use priority waitqueue to catch events before userspace
include/linux/wait.h | 12 +++++++++++-
kernel/sched/wait.c | 17 ++++++++++++++++-
virt/kvm/eventfd.c | 6 ++++--
next prev parent reply other threads:[~2020-10-27 14:40 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 17:53 [RFC PATCH 1/2] sched/wait: Add add_wait_queue_priority() David Woodhouse
2020-10-26 17:53 ` [RFC PATCH 2/2] kvm/eventfd: Use priority waitqueue to catch events before userspace David Woodhouse
2020-10-27 8:01 ` Paolo Bonzini
2020-10-27 10:15 ` David Woodhouse
2020-10-27 13:55 ` [PATCH 0/3] Allow in-kernel consumers to drain events from eventfd David Woodhouse
2020-10-27 13:55 ` [PATCH 1/3] eventfd: Export eventfd_ctx_do_read() David Woodhouse
2020-10-27 13:55 ` [PATCH 2/3] vfio/virqfd: Drain events from eventfd in virqfd_wakeup() David Woodhouse
2020-11-06 23:29 ` Alex Williamson
2020-11-08 9:17 ` Paolo Bonzini
2020-10-27 13:55 ` [PATCH 3/3] kvm/eventfd: Drain events from eventfd in irqfd_wakeup() David Woodhouse
2020-10-27 18:41 ` kernel test robot
2020-10-27 21:42 ` kernel test robot
2020-10-27 23:13 ` kernel test robot
2020-10-27 14:39 ` David Woodhouse [this message]
2020-10-27 14:39 ` [PATCH v2 1/2] sched/wait: Add add_wait_queue_priority() David Woodhouse
2020-10-27 19:09 ` Peter Zijlstra
2020-10-27 19:27 ` David Woodhouse
2020-10-27 20:30 ` Peter Zijlstra
2020-10-27 20:49 ` David Woodhouse
2020-10-27 21:32 ` David Woodhouse
2020-10-28 14:20 ` Peter Zijlstra
2020-10-28 14:44 ` Paolo Bonzini
2020-10-28 14:35 ` Peter Zijlstra
2020-11-04 9:35 ` David Woodhouse
2020-11-04 11:25 ` Paolo Bonzini
2020-11-06 10:17 ` Paolo Bonzini
2020-11-06 16:32 ` Alex Williamson
2020-11-06 17:18 ` David Woodhouse
2020-10-27 14:39 ` [PATCH v2 2/2] kvm/eventfd: Use priority waitqueue to catch events before userspace David Woodhouse
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