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virtio: Add support for no-reset virtio PCI PM

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If a virtio_pci_device supports native PCI power management and has the
No_Soft_Reset bit set, then skip resetting and reinitializing the device
when suspending and restoring the device. This allows system-wide low
power states like s2idle to be used in systems with stateful virtio
devices that can't simply be re-initialized (e.g. virtio-fs).

Signed-off-by: David Stevens <stevensd@chromium.org>
Message-Id: <20231208070754.3132339-1-stevensd@chromium.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
David Stevens 2023-12-08 16:07:54 +09:00 committed by Michael S. Tsirkin
parent d2c4f1928a
commit dff4fa0e57
1 changed files with 33 additions and 1 deletions
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34
drivers/virtio/virtio_pci_common.c
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@ -492,8 +492,40 @@ static int virtio_pci_restore(struct device *dev)
return virtio_device_restore(&vp_dev->vdev);
}
static bool vp_supports_pm_no_reset(struct device *dev)
{
struct pci_dev *pci_dev = to_pci_dev(dev);
u16 pmcsr;
if (!pci_dev->pm_cap)
return false;
pci_read_config_word(pci_dev, pci_dev->pm_cap + PCI_PM_CTRL, &pmcsr);
if (PCI_POSSIBLE_ERROR(pmcsr)) {
dev_err(dev, "Unable to query pmcsr");
return false;
}
return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
}
static int virtio_pci_suspend(struct device *dev)
{
return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_freeze(dev);
}
static int virtio_pci_resume(struct device *dev)
{
return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_restore(dev);
}
static const struct dev_pm_ops virtio_pci_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(virtio_pci_freeze, virtio_pci_restore)
.suspend = virtio_pci_suspend,
.resume = virtio_pci_resume,
.freeze = virtio_pci_freeze,
.thaw = virtio_pci_restore,
.poweroff = virtio_pci_freeze,
.restore = virtio_pci_restore,
};
#endif