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Tsirkin" , David Hildenbrand Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Stevens Subject: [PATCH 1/2] virtio_balloon: Give the balloon its own wakeup source Date: Mon, 18 Mar 2024 18:10:33 +0900 Message-ID: <20240318091034.535573-2-stevensd@google.com> X-Mailer: git-send-email 2.44.0.291.gc1ea87d7ee-goog In-Reply-To: <20240318091034.535573-1-stevensd@google.com> References: <20240318091034.535573-1-stevensd@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: David Stevens Wakeup sources don't support nesting multiple events, so sharing a single object between multiple drivers can result in one driver overriding the wakeup event processing period specified by another driver. Have the virtio balloon driver use the wakeup source of the device it is bound to rather than the wakeup source of the parent device, to avoid conflicts with the transport layer. Note that although the virtio balloon's virtio_device itself isn't what actually wakes up the device, it is responsible for processing wakeup events. In the same way that EPOLLWAKEUP uses a dedicated wakeup_source to prevent suspend when userspace is processing wakeup events, a dedicated wakeup_source is necessary when processing wakeup events in a higher layer in the kernel. Fixes: b12fbc3f787e ("virtio_balloon: stay awake while adjusting balloon") Signed-off-by: David Stevens Acked-by: David Hildenbrand --- drivers/virtio/virtio_balloon.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloo= n.c index 1f5b3dd31fcf..7fe7ef5f1c77 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -450,7 +450,7 @@ static void start_update_balloon_size(struct virtio_bal= loon *vb) vb->adjustment_signal_pending =3D true; if (!vb->adjustment_in_progress) { vb->adjustment_in_progress =3D true; - pm_stay_awake(vb->vdev->dev.parent); + pm_stay_awake(&vb->vdev->dev); } spin_unlock_irqrestore(&vb->adjustment_lock, flags); =20 @@ -462,7 +462,7 @@ static void end_update_balloon_size(struct virtio_ballo= on *vb) spin_lock_irq(&vb->adjustment_lock); if (!vb->adjustment_signal_pending && vb->adjustment_in_progress) { vb->adjustment_in_progress =3D false; - pm_relax(vb->vdev->dev.parent); 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Tsirkin" , David Hildenbrand Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Stevens Subject: [PATCH 2/2] virtio_balloon: Treat stats requests as wakeup events Date: Mon, 18 Mar 2024 18:10:34 +0900 Message-ID: <20240318091034.535573-3-stevensd@google.com> X-Mailer: git-send-email 2.44.0.291.gc1ea87d7ee-goog In-Reply-To: <20240318091034.535573-1-stevensd@google.com> References: <20240318091034.535573-1-stevensd@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: David Stevens Treat stats requests as wakeup events to ensure that the driver responds to device requests in a timely manner. Signed-off-by: David Stevens Acked-by: David Hildenbrand --- drivers/virtio/virtio_balloon.c | 75 ++++++++++++++++++++------------- 1 file changed, 46 insertions(+), 29 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloo= n.c index 7fe7ef5f1c77..402dec98e08c 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -121,11 +121,14 @@ struct virtio_balloon { struct page_reporting_dev_info pr_dev_info; =20 /* State for keeping the wakeup_source active while adjusting the balloon= */ - spinlock_t adjustment_lock; - bool adjustment_signal_pending; - bool adjustment_in_progress; + spinlock_t wakeup_lock; + bool processing_wakeup_event; + u32 wakeup_signal_mask; }; =20 +#define ADJUSTMENT_WAKEUP_SIGNAL (1 << 0) +#define STATS_WAKEUP_SIGNAL (1 << 1) + static const struct virtio_device_id id_table[] =3D { { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, { 0 }, @@ -140,6 +143,36 @@ static u32 page_to_balloon_pfn(struct page *page) return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; } =20 +static void start_wakeup_event(struct virtio_balloon *vb, u32 mask) +{ + unsigned long flags; + + spin_lock_irqsave(&vb->wakeup_lock, flags); + vb->wakeup_signal_mask |=3D mask; + if (!vb->processing_wakeup_event) { + vb->processing_wakeup_event =3D true; + pm_stay_awake(&vb->vdev->dev); + } + spin_unlock_irqrestore(&vb->wakeup_lock, flags); +} + +static void process_wakeup_event(struct virtio_balloon *vb, u32 mask) +{ + spin_lock_irq(&vb->wakeup_lock); + vb->wakeup_signal_mask &=3D ~mask; + spin_unlock_irq(&vb->wakeup_lock); +} + +static void finish_wakeup_event(struct virtio_balloon *vb) +{ + spin_lock_irq(&vb->wakeup_lock); + if (!vb->wakeup_signal_mask && vb->processing_wakeup_event) { + vb->processing_wakeup_event =3D false; + pm_relax(&vb->vdev->dev); + } + spin_unlock_irq(&vb->wakeup_lock); +} + static void balloon_ack(struct virtqueue *vq) { struct virtio_balloon *vb =3D vq->vdev->priv; @@ -370,8 +403,10 @@ static void stats_request(struct virtqueue *vq) struct virtio_balloon *vb =3D vq->vdev->priv; =20 spin_lock(&vb->stop_update_lock); - if (!vb->stop_update) + if (!vb->stop_update) { + start_wakeup_event(vb, STATS_WAKEUP_SIGNAL); queue_work(system_freezable_wq, &vb->update_balloon_stats_work); + } spin_unlock(&vb->stop_update_lock); } =20 @@ -444,29 +479,10 @@ static void virtio_balloon_queue_free_page_work(struc= t virtio_balloon *vb) =20 static void start_update_balloon_size(struct virtio_balloon *vb) { - unsigned long flags; - - spin_lock_irqsave(&vb->adjustment_lock, flags); - vb->adjustment_signal_pending =3D true; - if (!vb->adjustment_in_progress) { - vb->adjustment_in_progress =3D true; - pm_stay_awake(&vb->vdev->dev); - } - spin_unlock_irqrestore(&vb->adjustment_lock, flags); - + start_wakeup_event(vb, ADJUSTMENT_WAKEUP_SIGNAL); queue_work(system_freezable_wq, &vb->update_balloon_size_work); } =20 -static void end_update_balloon_size(struct virtio_balloon *vb) -{ - spin_lock_irq(&vb->adjustment_lock); - if (!vb->adjustment_signal_pending && vb->adjustment_in_progress) { - vb->adjustment_in_progress =3D false; - pm_relax(&vb->vdev->dev); - } - spin_unlock_irq(&vb->adjustment_lock); -} - static void virtballoon_changed(struct virtio_device *vdev) { struct virtio_balloon *vb =3D vdev->priv; @@ -495,7 +511,10 @@ static void update_balloon_stats_func(struct work_stru= ct *work) =20 vb =3D container_of(work, struct virtio_balloon, update_balloon_stats_work); + + process_wakeup_event(vb, STATS_WAKEUP_SIGNAL); stats_handle_request(vb); + finish_wakeup_event(vb); } =20 static void update_balloon_size_func(struct work_struct *work) @@ -506,9 +525,7 @@ static void update_balloon_size_func(struct work_struct= *work) vb =3D container_of(work, struct virtio_balloon, update_balloon_size_work); =20 - spin_lock_irq(&vb->adjustment_lock); - vb->adjustment_signal_pending =3D false; - spin_unlock_irq(&vb->adjustment_lock); + process_wakeup_event(vb, ADJUSTMENT_WAKEUP_SIGNAL); =20 diff =3D towards_target(vb); =20 @@ -523,7 +540,7 @@ static void update_balloon_size_func(struct work_struct= *work) if (diff) queue_work(system_freezable_wq, work); else - end_update_balloon_size(vb); + finish_wakeup_event(vb); } =20 static int init_vqs(struct virtio_balloon *vb) @@ -1027,7 +1044,7 @@ static int virtballoon_probe(struct virtio_device *vd= ev) goto out_unregister_oom; } =20 - spin_lock_init(&vb->adjustment_lock); + spin_lock_init(&vb->wakeup_lock); device_set_wakeup_capable(&vb->vdev->dev, true); =20 virtio_device_ready(vdev); --=20 2.44.0.291.gc1ea87d7ee-goog