Messages in this thread | | | Date | Thu, 18 Apr 2024 15:14:37 +0800 | Subject | Re: [PATCH 1/1] virtio: Add support for the virtio suspend feature | From | "Zhu, Lingshan" <> |
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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 <stevensd@chromium.org> > --- > 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 */
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