Michael S. Tsirkin
2023-Oct-03 13:20 UTC
[LINUX KERNEL PATCH v5 1/2] virtio_pci: Add freeze_mode for virtio_pci_common_cfg
On Tue, Sep 19, 2023 at 06:46:06PM +0800, Jiqian Chen wrote:> When guest vm does S3, Qemu will reset and clear some things of virtio > devices, but guest can't aware that, so that may cause some problems. > For excample, Qemu calls virtio_reset->virtio_gpu_gl_reset, that will > destroy render resources of virtio-gpu. As a result, after guest resume, > the display can't come back and we only saw a black screen. Due to guest > can't re-create all the resources, so we need to let Qemu not to destroy > them when S3. > > For above purpose, this patch add a new parameter named freeze_mode to > struct virtio_pci_common_cfg, and when guest suspends, it can set > freeze_mode to be FREEZE_S3, so that virtio devices can change their > reset behavior on Qemu side according to that mode. > > Signed-off-by: Jiqian Chen <Jiqian.Chen at amd.com> > --- > drivers/virtio/virtio.c | 13 +++++++++++++ > drivers/virtio/virtio_pci_modern.c | 9 +++++++++ > drivers/virtio/virtio_pci_modern_dev.c | 16 ++++++++++++++++ > include/linux/virtio_config.h | 1 + > include/linux/virtio_pci_modern.h | 2 ++ > include/uapi/linux/virtio_pci.h | 16 ++++++++++++++-- > 6 files changed, 55 insertions(+), 2 deletions(-) > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index 3893dc29eb26..b4eb8369d5a1 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -7,6 +7,7 @@ > #include <linux/idr.h> > #include <linux/of.h> > #include <uapi/linux/virtio_ids.h> > +#include <uapi/linux/virtio_pci.h> > > /* Unique numbering for virtio devices. */ > static DEFINE_IDA(virtio_index_ida); > @@ -486,10 +487,20 @@ void unregister_virtio_device(struct virtio_device *dev) > EXPORT_SYMBOL_GPL(unregister_virtio_device); > > #ifdef CONFIG_PM_SLEEP > +static void virtio_set_freeze_mode(struct virtio_device *dev, u16 mode) > +{ > + if (!dev->config->set_freeze_mode) > + return; > + might_sleep(); > + dev->config->set_freeze_mode(dev, mode); > +} > + > int virtio_device_freeze(struct virtio_device *dev) > { > struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); > > + virtio_set_freeze_mode(dev, VIRTIO_PCI_FREEZE_MODE_FREEZE_S3); > + > virtio_config_disable(dev); > > dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; > @@ -544,6 +555,8 @@ int virtio_device_restore(struct virtio_device *dev) > > virtio_config_enable(dev); > > + virtio_set_freeze_mode(dev, VIRTIO_PCI_FREEZE_MODE_UNFREEZE); > + > return 0; > > err: > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > index d6bb68ba84e5..846b70919cbd 100644 > --- a/drivers/virtio/virtio_pci_modern.c > +++ b/drivers/virtio/virtio_pci_modern.c > @@ -491,6 +491,13 @@ static bool vp_get_shm_region(struct virtio_device *vdev, > return true; > } > > +static void vp_set_freeze_mode(struct virtio_device *vdev, u16 mode) > +{ > + struct virtio_pci_device *vp_dev = to_vp_device(vdev); > + > + vp_modern_set_freeze_mode(&vp_dev->mdev, mode); > +} > + > static const struct virtio_config_ops virtio_pci_config_nodev_ops = { > .get = NULL, > .set = NULL, > @@ -509,6 +516,7 @@ static const struct virtio_config_ops virtio_pci_config_nodev_ops = { > .get_shm_region = vp_get_shm_region, > .disable_vq_and_reset = vp_modern_disable_vq_and_reset, > .enable_vq_after_reset = vp_modern_enable_vq_after_reset, > + .set_freeze_mode = vp_set_freeze_mode, > }; > > static const struct virtio_config_ops virtio_pci_config_ops = { > @@ -529,6 +537,7 @@ static const struct virtio_config_ops virtio_pci_config_ops = { > .get_shm_region = vp_get_shm_region, > .disable_vq_and_reset = vp_modern_disable_vq_and_reset, > .enable_vq_after_reset = vp_modern_enable_vq_after_reset, > + .set_freeze_mode = vp_set_freeze_mode, > }; > > /* the PCI probing function */ > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c > index aad7d9296e77..4a6f7d130b6e 100644 > --- a/drivers/virtio/virtio_pci_modern_dev.c > +++ b/drivers/virtio/virtio_pci_modern_dev.c > @@ -203,6 +203,8 @@ static inline void check_offsets(void) > offsetof(struct virtio_pci_common_cfg, queue_used_lo)); > BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI !> offsetof(struct virtio_pci_common_cfg, queue_used_hi)); > + BUILD_BUG_ON(VIRTIO_PCI_COMMON_F_MODE !> + offsetof(struct virtio_pci_common_cfg, freeze_mode)); > } > > /* > @@ -714,6 +716,20 @@ void __iomem *vp_modern_map_vq_notify(struct virtio_pci_modern_device *mdev, > } > EXPORT_SYMBOL_GPL(vp_modern_map_vq_notify); > > +/* > + * vp_modern_set_freeze_mode - set freeze mode to device > + * @mdev: the modern virtio-pci device > + * @mode: the mode set to device > + */ > +void vp_modern_set_freeze_mode(struct virtio_pci_modern_device *mdev, > + u16 mode) > +{ > + struct virtio_pci_common_cfg __iomem *cfg = mdev->common; > + > + vp_iowrite16(mode, &cfg->freeze_mode); > +} > +EXPORT_SYMBOL_GPL(vp_modern_set_freeze_mode); > + > MODULE_VERSION("0.1"); > MODULE_DESCRIPTION("Modern Virtio PCI Device"); > MODULE_AUTHOR("Jason Wang <jasowang at redhat.com>"); > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > index 2b3438de2c4d..2a7443ff7f12 100644 > --- a/include/linux/virtio_config.h > +++ b/include/linux/virtio_config.h > @@ -120,6 +120,7 @@ struct virtio_config_ops { > struct virtio_shm_region *region, u8 id); > int (*disable_vq_and_reset)(struct virtqueue *vq); > int (*enable_vq_after_reset)(struct virtqueue *vq); > + void (*set_freeze_mode)(struct virtio_device *vdev, u16 mode); > }; > > /* If driver didn't advertise the feature, it will never appear. */ > diff --git a/include/linux/virtio_pci_modern.h b/include/linux/virtio_pci_modern.h > index 067ac1d789bc..ba6eed216ded 100644 > --- a/include/linux/virtio_pci_modern.h > +++ b/include/linux/virtio_pci_modern.h > @@ -121,4 +121,6 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev); > void vp_modern_remove(struct virtio_pci_modern_device *mdev); > int vp_modern_get_queue_reset(struct virtio_pci_modern_device *mdev, u16 index); > void vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16 index); > +void vp_modern_set_freeze_mode(struct virtio_pci_modern_device *mdev, > + u16 mode); > #endif > diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h > index f703afc7ad31..725ace458a1b 100644 > --- a/include/uapi/linux/virtio_pci.h > +++ b/include/uapi/linux/virtio_pci.h > @@ -140,6 +140,15 @@ struct virtio_pci_notify_cap { > __le32 notify_off_multiplier; /* Multiplier for queue_notify_off. */ > }; > > +typedef enum { > + VIRTIO_PCI_FREEZE_MODE_UNFREEZE = 0, > + VIRTIO_PCI_FREEZE_MODE_FREEZE_S3 = 3, > +} virtio_pci_freeze_mode_t;we don't normally do typedefs.> + > +#define VIRTIO_PCI_FREEZE_MODE_MASK \ > + ((1 << VIRTIO_PCI_FREEZE_MODE_UNFREEZE) | \ > + (1 << VIRTIO_PCI_FREEZE_MODE_FREEZE_S3)) > +not sure why is this useful generally.> /* Fields in VIRTIO_PCI_CAP_COMMON_CFG: */ > struct virtio_pci_common_cfg { > /* About the whole device. */ > @@ -164,6 +173,8 @@ struct virtio_pci_common_cfg { > __le32 queue_avail_hi; /* read-write */ > __le32 queue_used_lo; /* read-write */ > __le32 queue_used_hi; /* read-write */ > + > + __le16 freeze_mode; /* read-write */ > }; >Your patch will likely break uses of sizeof(struct virtio_pci_common_cfg) on existing devices.> /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */ > @@ -202,8 +213,9 @@ struct virtio_pci_cfg_cap { > #define VIRTIO_PCI_COMMON_Q_AVAILHI 44 > #define VIRTIO_PCI_COMMON_Q_USEDLO 48 > #define VIRTIO_PCI_COMMON_Q_USEDHI 52 > -#define VIRTIO_PCI_COMMON_Q_NDATA 56 > -#define VIRTIO_PCI_COMMON_Q_RESET 58 > +#define VIRTIO_PCI_COMMON_F_MODE 56F_ here stands for freeze? Please don't abbreviate. Q for queue is a pun that works, F for freeze doesn't.> +#define VIRTIO_PCI_COMMON_Q_NDATA 58 > +#define VIRTIO_PCI_COMMON_Q_RESET 60 > > #endif /* VIRTIO_PCI_NO_MODERN */ > > -- > 2.34.1