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virtio_mmio: Restore guest page size on resume

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[ Upstream commit e0c2ce8217955537dd5434baeba061f209797119 ]

Virtio devices might lose their state when the VMM is restarted
after a suspend to disk (hibernation) cycle. This means that the
guest page size register must be restored for the virtio_mmio legacy
interface, since otherwise the virtio queues are not functional.

This is particularly problematic for QEMU that currently still defaults
to using the legacy interface for virtio_mmio. Write the guest page
size register again in virtio_mmio_restore() to make legacy virtio_mmio
devices work correctly after hibernation.

Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Message-Id: <20220621110621.3638025-3-stephan.gerhold@kernkonzept.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Stephan Gerhold
2022-06-21 13:06:21 +02:00
committed by Greg Kroah-Hartman
parent d611580032
commit 93135dca8c
1 changed files with 3 additions and 0 deletions
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3
drivers/virtio/virtio_mmio.c
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@@ -556,6 +556,9 @@ static int virtio_mmio_restore(struct device *dev)
{ {
struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev); struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
if (vm_dev->version == 1)
writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
return virtio_device_restore(&vm_dev->vdev); return virtio_device_restore(&vm_dev->vdev);
} }