This series implements support for the virtio device suspend feature
that is under discussion. Unfortunately, the virtio mailing list is
currently being migrated, so recent discussion of the proposal is not
archived anywhere. There current version of the proposal is a
combination of [1] and [2].
[1] https://lore.kernel.org/all/[email protected]/
[2] https://lists.oasis-open.org/archives/virtio-comment/202402/msg00088.html
David Stevens (1):
virtio: Add support for the virtio suspend feature
drivers/virtio/virtio.c | 32 ++++++++++++++++++++++++++++++
drivers/virtio/virtio_pci_common.c | 29 +++++++++++----------------
drivers/virtio/virtio_pci_modern.c | 19 ++++++++++++++++++
include/linux/virtio.h | 2 ++
include/uapi/linux/virtio_config.h | 10 +++++++++-
5 files changed, 74 insertions(+), 18 deletions(-)
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
--
2.44.0.683.g7961c838ac-goog
Add support for the VIRTIO_F_SUSPEND feature. When this feature is
negotiated, power management can use it to suspend virtio devices
instead of resorting to resetting the devices entirely.
Signed-off-by: David Stevens <[email protected]>
---
drivers/virtio/virtio.c | 32 ++++++++++++++++++++++++++++++
drivers/virtio/virtio_pci_common.c | 29 +++++++++++----------------
drivers/virtio/virtio_pci_modern.c | 19 ++++++++++++++++++
include/linux/virtio.h | 2 ++
include/uapi/linux/virtio_config.h | 10 +++++++++-
5 files changed, 74 insertions(+), 18 deletions(-)
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index f4080692b351..cd11495a5098 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/virtio.h>
+#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/virtio_config.h>
#include <linux/virtio_anchor.h>
@@ -580,6 +581,37 @@ int virtio_device_restore(struct virtio_device *dev)
return ret;
}
EXPORT_SYMBOL_GPL(virtio_device_restore);
+
+static int virtio_device_set_suspend_bit(struct virtio_device *dev, bool enabled)
+{
+ u8 status, target;
+
+ status = dev->config->get_status(dev);
+ if (enabled)
+ target = status | VIRTIO_CONFIG_S_SUSPEND;
+ else
+ target = status & ~VIRTIO_CONFIG_S_SUSPEND;
+ dev->config->set_status(dev, target);
+
+ while ((status = dev->config->get_status(dev)) != target) {
+ if (status & VIRTIO_CONFIG_S_NEEDS_RESET)
+ return -EIO;
+ mdelay(10);
+ }
+ return 0;
+}
+
+int virtio_device_suspend(struct virtio_device *dev)
+{
+ return virtio_device_set_suspend_bit(dev, true);
+}
+EXPORT_SYMBOL_GPL(virtio_device_suspend);
+
+int virtio_device_resume(struct virtio_device *dev)
+{
+ return virtio_device_set_suspend_bit(dev, false);
+}
+EXPORT_SYMBOL_GPL(virtio_device_resume);
#endif
static int virtio_init(void)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index b655fccaf773..4d542de05970 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -495,31 +495,26 @@ 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)
+static int virtio_pci_suspend(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;
- }
+ struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
- return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
-}
+ if (virtio_has_feature(&vp_dev->vdev, VIRTIO_F_SUSPEND))
+ return virtio_device_suspend(&vp_dev->vdev);
-static int virtio_pci_suspend(struct device *dev)
-{
- return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_freeze(dev);
+ return virtio_pci_freeze(dev);
}
static int virtio_pci_resume(struct device *dev)
{
- return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_restore(dev);
+ struct pci_dev *pci_dev = to_pci_dev(dev);
+ struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+
+ if (virtio_has_feature(&vp_dev->vdev, VIRTIO_F_SUSPEND))
+ return virtio_device_resume(&vp_dev->vdev);
+
+ return virtio_pci_restore(dev);
}
static const struct dev_pm_ops virtio_pci_pm_ops = {
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index f62b530aa3b5..ac8734526b8d 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -209,6 +209,22 @@ static void vp_modern_avq_deactivate(struct virtio_device *vdev)
__virtqueue_break(admin_vq->info.vq);
}
+static bool vp_supports_pm_no_reset(struct pci_dev *pci_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(&pci_dev->dev, "Unable to query pmcsr");
+ return false;
+ }
+
+ return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
+}
+
static void vp_transport_features(struct virtio_device *vdev, u64 features)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
@@ -223,6 +239,9 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
if (features & BIT_ULL(VIRTIO_F_ADMIN_VQ))
__virtio_set_bit(vdev, VIRTIO_F_ADMIN_VQ);
+
+ if (features & BIT_ULL(VIRTIO_F_SUSPEND) && vp_supports_pm_no_reset(pci_dev))
+ __virtio_set_bit(vdev, VIRTIO_F_SUSPEND);
}
static int __vp_check_common_size_one_feature(struct virtio_device *vdev, u32 fbit,
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index b0201747a263..8e456b04114e 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -160,6 +160,8 @@ void virtio_config_changed(struct virtio_device *dev);
#ifdef CONFIG_PM_SLEEP
int virtio_device_freeze(struct virtio_device *dev);
int virtio_device_restore(struct virtio_device *dev);
+int virtio_device_suspend(struct virtio_device *dev);
+int virtio_device_resume(struct virtio_device *dev);
#endif
void virtio_reset_device(struct virtio_device *dev);
diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
index 2445f365bce7..4a6e2c28ea76 100644
--- a/include/uapi/linux/virtio_config.h
+++ b/include/uapi/linux/virtio_config.h
@@ -40,6 +40,8 @@
#define VIRTIO_CONFIG_S_DRIVER_OK 4
/* Driver has finished configuring features */
#define VIRTIO_CONFIG_S_FEATURES_OK 8
+/* Driver has suspended the device */
+#define VIRTIO_CONFIG_S_SUSPEND 0x10
/* Device entered invalid state, driver must reset it */
#define VIRTIO_CONFIG_S_NEEDS_RESET 0x40
/* We've given up on this device. */
@@ -52,7 +54,7 @@
* rest are per-device feature bits.
*/
#define VIRTIO_TRANSPORT_F_START 28
-#define VIRTIO_TRANSPORT_F_END 42
+#define VIRTIO_TRANSPORT_F_END 43
#ifndef VIRTIO_CONFIG_NO_LEGACY
/* Do we get callbacks when the ring is completely used, even if we've
@@ -120,4 +122,10 @@
*/
#define VIRTIO_F_ADMIN_VQ 41
+/*
+ * This feature indicates that the driver can suspend the device via the
+ * suspend bit in the device status byte.
+ */
+#define VIRTIO_F_SUSPEND 42
+
#endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
--
2.44.0.683.g7961c838ac-goog
On 4/17/2024 4:54 PM, David Stevens wrote:
> Add support for the VIRTIO_F_SUSPEND feature. When this feature is
> negotiated, power management can use it to suspend virtio devices
> instead of resorting to resetting the devices entirely.
>
> Signed-off-by: David Stevens <[email protected]>
> ---
> drivers/virtio/virtio.c | 32 ++++++++++++++++++++++++++++++
> drivers/virtio/virtio_pci_common.c | 29 +++++++++++----------------
> drivers/virtio/virtio_pci_modern.c | 19 ++++++++++++++++++
> include/linux/virtio.h | 2 ++
> include/uapi/linux/virtio_config.h | 10 +++++++++-
> 5 files changed, 74 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index f4080692b351..cd11495a5098 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -1,5 +1,6 @@
> // SPDX-License-Identifier: GPL-2.0-only
> #include <linux/virtio.h>
> +#include <linux/delay.h>
> #include <linux/spinlock.h>
> #include <linux/virtio_config.h>
> #include <linux/virtio_anchor.h>
> @@ -580,6 +581,37 @@ int virtio_device_restore(struct virtio_device *dev)
> return ret;
> }
> EXPORT_SYMBOL_GPL(virtio_device_restore);
> +
> +static int virtio_device_set_suspend_bit(struct virtio_device *dev, bool enabled)
> +{
> + u8 status, target;
> +
> + status = dev->config->get_status(dev);
> + if (enabled)
> + target = status | VIRTIO_CONFIG_S_SUSPEND;
> + else
> + target = status & ~VIRTIO_CONFIG_S_SUSPEND;
> + dev->config->set_status(dev, target);
I think it is better to verify whether the device SUSPEND bit is
already set or clear, we can just return if status == target.
Thanks
Zhu Lingshan
> +
> + while ((status = dev->config->get_status(dev)) != target) {
> + if (status & VIRTIO_CONFIG_S_NEEDS_RESET)
> + return -EIO;
> + mdelay(10);
> + }
> + return 0;
> +}
> +
> +int virtio_device_suspend(struct virtio_device *dev)
> +{
> + return virtio_device_set_suspend_bit(dev, true);
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_suspend);
> +
> +int virtio_device_resume(struct virtio_device *dev)
> +{
> + return virtio_device_set_suspend_bit(dev, false);
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_resume);
> #endif
>
> static int virtio_init(void)
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index b655fccaf773..4d542de05970 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -495,31 +495,26 @@ 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)
> +static int virtio_pci_suspend(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;
> - }
> + struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
>
> - return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
> -}
> + if (virtio_has_feature(&vp_dev->vdev, VIRTIO_F_SUSPEND))
> + return virtio_device_suspend(&vp_dev->vdev);
>
> -static int virtio_pci_suspend(struct device *dev)
> -{
> - return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_freeze(dev);
> + return virtio_pci_freeze(dev);
> }
>
> static int virtio_pci_resume(struct device *dev)
> {
> - return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_restore(dev);
> + struct pci_dev *pci_dev = to_pci_dev(dev);
> + struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> +
> + if (virtio_has_feature(&vp_dev->vdev, VIRTIO_F_SUSPEND))
> + return virtio_device_resume(&vp_dev->vdev);
> +
> + return virtio_pci_restore(dev);
> }
>
> static const struct dev_pm_ops virtio_pci_pm_ops = {
> diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> index f62b530aa3b5..ac8734526b8d 100644
> --- a/drivers/virtio/virtio_pci_modern.c
> +++ b/drivers/virtio/virtio_pci_modern.c
> @@ -209,6 +209,22 @@ static void vp_modern_avq_deactivate(struct virtio_device *vdev)
> __virtqueue_break(admin_vq->info.vq);
> }
>
> +static bool vp_supports_pm_no_reset(struct pci_dev *pci_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(&pci_dev->dev, "Unable to query pmcsr");
> + return false;
> + }
> +
> + return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
> +}
> +
> static void vp_transport_features(struct virtio_device *vdev, u64 features)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> @@ -223,6 +239,9 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
>
> if (features & BIT_ULL(VIRTIO_F_ADMIN_VQ))
> __virtio_set_bit(vdev, VIRTIO_F_ADMIN_VQ);
> +
> + if (features & BIT_ULL(VIRTIO_F_SUSPEND) && vp_supports_pm_no_reset(pci_dev))
> + __virtio_set_bit(vdev, VIRTIO_F_SUSPEND);
> }
>
> static int __vp_check_common_size_one_feature(struct virtio_device *vdev, u32 fbit,
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index b0201747a263..8e456b04114e 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -160,6 +160,8 @@ void virtio_config_changed(struct virtio_device *dev);
> #ifdef CONFIG_PM_SLEEP
> int virtio_device_freeze(struct virtio_device *dev);
> int virtio_device_restore(struct virtio_device *dev);
> +int virtio_device_suspend(struct virtio_device *dev);
> +int virtio_device_resume(struct virtio_device *dev);
> #endif
> void virtio_reset_device(struct virtio_device *dev);
>
> diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> index 2445f365bce7..4a6e2c28ea76 100644
> --- a/include/uapi/linux/virtio_config.h
> +++ b/include/uapi/linux/virtio_config.h
> @@ -40,6 +40,8 @@
> #define VIRTIO_CONFIG_S_DRIVER_OK 4
> /* Driver has finished configuring features */
> #define VIRTIO_CONFIG_S_FEATURES_OK 8
> +/* Driver has suspended the device */
> +#define VIRTIO_CONFIG_S_SUSPEND 0x10
> /* Device entered invalid state, driver must reset it */
> #define VIRTIO_CONFIG_S_NEEDS_RESET 0x40
> /* We've given up on this device. */
> @@ -52,7 +54,7 @@
> * rest are per-device feature bits.
> */
> #define VIRTIO_TRANSPORT_F_START 28
> -#define VIRTIO_TRANSPORT_F_END 42
> +#define VIRTIO_TRANSPORT_F_END 43
>
> #ifndef VIRTIO_CONFIG_NO_LEGACY
> /* Do we get callbacks when the ring is completely used, even if we've
> @@ -120,4 +122,10 @@
> */
> #define VIRTIO_F_ADMIN_VQ 41
>
> +/*
> + * This feature indicates that the driver can suspend the device via the
> + * suspend bit in the device status byte.
> + */
> +#define VIRTIO_F_SUSPEND 42
> +
> #endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
On Thu, Apr 18, 2024 at 03:14:37PM +0800, Zhu, Lingshan wrote:
>
>
> On 4/17/2024 4:54 PM, David Stevens wrote:
> > Add support for the VIRTIO_F_SUSPEND feature. When this feature is
> > negotiated, power management can use it to suspend virtio devices
> > instead of resorting to resetting the devices entirely.
> >
> > Signed-off-by: David Stevens <[email protected]>
> > ---
> > drivers/virtio/virtio.c | 32 ++++++++++++++++++++++++++++++
> > drivers/virtio/virtio_pci_common.c | 29 +++++++++++----------------
> > drivers/virtio/virtio_pci_modern.c | 19 ++++++++++++++++++
> > include/linux/virtio.h | 2 ++
> > include/uapi/linux/virtio_config.h | 10 +++++++++-
> > 5 files changed, 74 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> > index f4080692b351..cd11495a5098 100644
> > --- a/drivers/virtio/virtio.c
> > +++ b/drivers/virtio/virtio.c
> > @@ -1,5 +1,6 @@
> > // SPDX-License-Identifier: GPL-2.0-only
> > #include <linux/virtio.h>
> > +#include <linux/delay.h>
> > #include <linux/spinlock.h>
> > #include <linux/virtio_config.h>
> > #include <linux/virtio_anchor.h>
> > @@ -580,6 +581,37 @@ int virtio_device_restore(struct virtio_device *dev)
> > return ret;
> > }
> > EXPORT_SYMBOL_GPL(virtio_device_restore);
> > +
> > +static int virtio_device_set_suspend_bit(struct virtio_device *dev, bool enabled)
> > +{
> > + u8 status, target;
> > +
> > + status = dev->config->get_status(dev);
> > + if (enabled)
> > + target = status | VIRTIO_CONFIG_S_SUSPEND;
> > + else
> > + target = status & ~VIRTIO_CONFIG_S_SUSPEND;
> > + dev->config->set_status(dev, target);
> I think it is better to verify whether the device SUSPEND bit is
> already set or clear, we can just return if status == target.
>
> Thanks
> Zhu Lingshan
> > +
> > + while ((status = dev->config->get_status(dev)) != target) {
> > + if (status & VIRTIO_CONFIG_S_NEEDS_RESET)
> > + return -EIO;
> > + mdelay(10);
Bad device state (set by surprise removal) should also
be handled here I think.
> > + }
> > + return 0;
> > +}
> > +
> > +int virtio_device_suspend(struct virtio_device *dev)
> > +{
> > + return virtio_device_set_suspend_bit(dev, true);
> > +}
> > +EXPORT_SYMBOL_GPL(virtio_device_suspend);
> > +
> > +int virtio_device_resume(struct virtio_device *dev)
> > +{
> > + return virtio_device_set_suspend_bit(dev, false);
> > +}
> > +EXPORT_SYMBOL_GPL(virtio_device_resume);
> > #endif
> > static int virtio_init(void)
> > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > index b655fccaf773..4d542de05970 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -495,31 +495,26 @@ 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)
> > +static int virtio_pci_suspend(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;
> > - }
> > + struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> > - return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
> > -}
> > + if (virtio_has_feature(&vp_dev->vdev, VIRTIO_F_SUSPEND))
> > + return virtio_device_suspend(&vp_dev->vdev);
> > -static int virtio_pci_suspend(struct device *dev)
> > -{
> > - return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_freeze(dev);
> > + return virtio_pci_freeze(dev);
> > }
> > static int virtio_pci_resume(struct device *dev)
> > {
> > - return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_restore(dev);
> > + struct pci_dev *pci_dev = to_pci_dev(dev);
> > + struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> > +
> > + if (virtio_has_feature(&vp_dev->vdev, VIRTIO_F_SUSPEND))
> > + return virtio_device_resume(&vp_dev->vdev);
> > +
> > + return virtio_pci_restore(dev);
> > }
> > static const struct dev_pm_ops virtio_pci_pm_ops = {
> > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > index f62b530aa3b5..ac8734526b8d 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -209,6 +209,22 @@ static void vp_modern_avq_deactivate(struct virtio_device *vdev)
> > __virtqueue_break(admin_vq->info.vq);
> > }
> > +static bool vp_supports_pm_no_reset(struct pci_dev *pci_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(&pci_dev->dev, "Unable to query pmcsr");
> > + return false;
> > + }
> > +
> > + return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
> > +}
> > +
> > static void vp_transport_features(struct virtio_device *vdev, u64 features)
> > {
> > struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > @@ -223,6 +239,9 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
> > if (features & BIT_ULL(VIRTIO_F_ADMIN_VQ))
> > __virtio_set_bit(vdev, VIRTIO_F_ADMIN_VQ);
> > +
> > + if (features & BIT_ULL(VIRTIO_F_SUSPEND) && vp_supports_pm_no_reset(pci_dev))
> > + __virtio_set_bit(vdev, VIRTIO_F_SUSPEND);
> > }
> > static int __vp_check_common_size_one_feature(struct virtio_device *vdev, u32 fbit,
> > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > index b0201747a263..8e456b04114e 100644
> > --- a/include/linux/virtio.h
> > +++ b/include/linux/virtio.h
> > @@ -160,6 +160,8 @@ void virtio_config_changed(struct virtio_device *dev);
> > #ifdef CONFIG_PM_SLEEP
> > int virtio_device_freeze(struct virtio_device *dev);
> > int virtio_device_restore(struct virtio_device *dev);
> > +int virtio_device_suspend(struct virtio_device *dev);
> > +int virtio_device_resume(struct virtio_device *dev);
> > #endif
> > void virtio_reset_device(struct virtio_device *dev);
> > diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> > index 2445f365bce7..4a6e2c28ea76 100644
> > --- a/include/uapi/linux/virtio_config.h
> > +++ b/include/uapi/linux/virtio_config.h
> > @@ -40,6 +40,8 @@
> > #define VIRTIO_CONFIG_S_DRIVER_OK 4
> > /* Driver has finished configuring features */
> > #define VIRTIO_CONFIG_S_FEATURES_OK 8
> > +/* Driver has suspended the device */
> > +#define VIRTIO_CONFIG_S_SUSPEND 0x10
> > /* Device entered invalid state, driver must reset it */
> > #define VIRTIO_CONFIG_S_NEEDS_RESET 0x40
> > /* We've given up on this device. */
> > @@ -52,7 +54,7 @@
> > * rest are per-device feature bits.
> > */
> > #define VIRTIO_TRANSPORT_F_START 28
> > -#define VIRTIO_TRANSPORT_F_END 42
> > +#define VIRTIO_TRANSPORT_F_END 43
> > #ifndef VIRTIO_CONFIG_NO_LEGACY
> > /* Do we get callbacks when the ring is completely used, even if we've
> > @@ -120,4 +122,10 @@
> > */
> > #define VIRTIO_F_ADMIN_VQ 41
> > +/*
> > + * This feature indicates that the driver can suspend the device via the
> > + * suspend bit in the device status byte.
> > + */
> > +#define VIRTIO_F_SUSPEND 42
> > +
> > #endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */