Re: [PATCH 1/1] virtio: Add support for the virtio suspend feature
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
> > ---
> > 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
> > +#include
> > #include
> > #include
> > #include
> > @@ -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(_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, );
> > - 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(_dev->vdev, VIRTIO_F_SUSPEND))
> > + return virtio_device_suspend(_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(_dev->vdev, VIRTIO_F_SUSPEND))
> > + return virtio_device_resume(_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, );
> > + if (PCI_POSSIBLE_ERROR(pmcsr)) {
> > + dev_err(_dev->dev, "Unable to query pmcsr");
> > + return false;
Re: [PATCH 1/1] virtio: Add support for the virtio suspend feature
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
---
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
+#include
#include
#include
#include
@@ -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(_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, );
- 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(_dev->vdev, VIRTIO_F_SUSPEND))
+ return virtio_device_suspend(_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(_dev->vdev, VIRTIO_F_SUSPEND))
+ return virtio_device_resume(_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, );
+ if (PCI_POSSIBLE_ERROR(pmcsr)) {
+ dev_err(_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 &
