| Message ID | 20200731065533.4144-2-lingshan.zhu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | IRQ offloading for vDPA | expand |
On 2020/7/31 下午2:55, Zhu Lingshan wrote: > This commit introduces struct vhost_vring_call which replaced > raw struct eventfd_ctx *call_ctx in struct vhost_virtqueue. > Besides eventfd_ctx, it contains a spin lock and an > irq_bypass_producer in its structure. > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> > Suggested-by: Jason Wang <jasowang@redhat.com> > --- > drivers/vhost/vdpa.c | 4 ++-- > drivers/vhost/vhost.c | 22 ++++++++++++++++------ > drivers/vhost/vhost.h | 9 ++++++++- > 3 files changed, 26 insertions(+), 9 deletions(-) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index a54b60d6623f..df3cf386b0cd 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -96,7 +96,7 @@ static void handle_vq_kick(struct vhost_work *work) > static irqreturn_t vhost_vdpa_virtqueue_cb(void *private) > { > struct vhost_virtqueue *vq = private; > - struct eventfd_ctx *call_ctx = vq->call_ctx; > + struct eventfd_ctx *call_ctx = vq->call_ctx.ctx; > > if (call_ctx) > eventfd_signal(call_ctx, 1); > @@ -382,7 +382,7 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, > break; > > case VHOST_SET_VRING_CALL: > - if (vq->call_ctx) { > + if (vq->call_ctx.ctx) { > cb.callback = vhost_vdpa_virtqueue_cb; > cb.private = vq; > } else { > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index d7b8df3edffc..9f1a845a9302 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -298,6 +298,13 @@ static void vhost_vq_meta_reset(struct vhost_dev *d) > __vhost_vq_meta_reset(d->vqs[i]); > } > > +static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx) > +{ > + call_ctx->ctx = NULL; > + memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer)); > + spin_lock_init(&call_ctx->ctx_lock); > +} > + > static void vhost_vq_reset(struct vhost_dev *dev, > struct vhost_virtqueue *vq) > { > @@ -319,13 +326,13 @@ static void vhost_vq_reset(struct vhost_dev *dev, > vq->log_base = NULL; > vq->error_ctx = NULL; > vq->kick = NULL; > - vq->call_ctx = NULL; > vq->log_ctx = NULL; > vhost_reset_is_le(vq); > vhost_disable_cross_endian(vq); > vq->busyloop_timeout = 0; > vq->umem = NULL; > vq->iotlb = NULL; > + vhost_vring_call_reset(&vq->call_ctx); > __vhost_vq_meta_reset(vq); > } > > @@ -685,8 +692,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev) > eventfd_ctx_put(dev->vqs[i]->error_ctx); > if (dev->vqs[i]->kick) > fput(dev->vqs[i]->kick); > - if (dev->vqs[i]->call_ctx) > - eventfd_ctx_put(dev->vqs[i]->call_ctx); > + if (dev->vqs[i]->call_ctx.ctx) > + eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx); > vhost_vq_reset(dev, dev->vqs[i]); > } > vhost_dev_free_iovecs(dev); > @@ -1629,7 +1636,10 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg > r = PTR_ERR(ctx); > break; > } > - swap(ctx, vq->call_ctx); > + > + spin_lock(&vq->call_ctx.ctx_lock); > + swap(ctx, vq->call_ctx.ctx); > + spin_unlock(&vq->call_ctx.ctx_lock); > break; > case VHOST_SET_VRING_ERR: > if (copy_from_user(&f, argp, sizeof f)) { > @@ -2440,8 +2450,8 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) > void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) > { > /* Signal the Guest tell them we used something up. */ > - if (vq->call_ctx && vhost_notify(dev, vq)) > - eventfd_signal(vq->call_ctx, 1); > + if (vq->call_ctx.ctx && vhost_notify(dev, vq)) > + eventfd_signal(vq->call_ctx.ctx, 1); > } > EXPORT_SYMBOL_GPL(vhost_signal); > > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index c8e96a095d3b..38eb1aa3b68d 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -13,6 +13,7 @@ > #include <linux/virtio_ring.h> > #include <linux/atomic.h> > #include <linux/vhost_iotlb.h> > +#include <linux/irqbypass.h> > > struct vhost_work; > typedef void (*vhost_work_fn_t)(struct vhost_work *work); > @@ -60,6 +61,12 @@ enum vhost_uaddr_type { > VHOST_NUM_ADDRS = 3, > }; > > +struct vhost_vring_call { > + struct eventfd_ctx *ctx; > + struct irq_bypass_producer producer; > + spinlock_t ctx_lock; It's not clear to me why we need ctx_lock here. Thanks > +}; > + > /* The virtqueue structure describes a queue attached to a device. */ > struct vhost_virtqueue { > struct vhost_dev *dev; > @@ -72,7 +79,7 @@ struct vhost_virtqueue { > vring_used_t __user *used; > const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS]; > struct file *kick; > - struct eventfd_ctx *call_ctx; > + struct vhost_vring_call call_ctx; > struct eventfd_ctx *error_ctx; > struct eventfd_ctx *log_ctx; >
On 2020/8/4 下午4:42, Zhu, Lingshan wrote: > > > On 8/4/2020 4:38 PM, Jason Wang wrote: >> >> On 2020/7/31 下午2:55, Zhu Lingshan wrote: >>> This commit introduces struct vhost_vring_call which replaced >>> raw struct eventfd_ctx *call_ctx in struct vhost_virtqueue. >>> Besides eventfd_ctx, it contains a spin lock and an >>> irq_bypass_producer in its structure. >>> >>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> >>> Suggested-by: Jason Wang <jasowang@redhat.com> >>> --- >>> drivers/vhost/vdpa.c | 4 ++-- >>> drivers/vhost/vhost.c | 22 ++++++++++++++++------ >>> drivers/vhost/vhost.h | 9 ++++++++- >>> 3 files changed, 26 insertions(+), 9 deletions(-) >>> >>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c >>> index a54b60d6623f..df3cf386b0cd 100644 >>> --- a/drivers/vhost/vdpa.c >>> +++ b/drivers/vhost/vdpa.c >>> @@ -96,7 +96,7 @@ static void handle_vq_kick(struct vhost_work *work) >>> static irqreturn_t vhost_vdpa_virtqueue_cb(void *private) >>> { >>> struct vhost_virtqueue *vq = private; >>> - struct eventfd_ctx *call_ctx = vq->call_ctx; >>> + struct eventfd_ctx *call_ctx = vq->call_ctx.ctx; >>> if (call_ctx) >>> eventfd_signal(call_ctx, 1); >>> @@ -382,7 +382,7 @@ static long vhost_vdpa_vring_ioctl(struct >>> vhost_vdpa *v, unsigned int cmd, >>> break; >>> case VHOST_SET_VRING_CALL: >>> - if (vq->call_ctx) { >>> + if (vq->call_ctx.ctx) { >>> cb.callback = vhost_vdpa_virtqueue_cb; >>> cb.private = vq; >>> } else { >>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >>> index d7b8df3edffc..9f1a845a9302 100644 >>> --- a/drivers/vhost/vhost.c >>> +++ b/drivers/vhost/vhost.c >>> @@ -298,6 +298,13 @@ static void vhost_vq_meta_reset(struct >>> vhost_dev *d) >>> __vhost_vq_meta_reset(d->vqs[i]); >>> } >>> +static void vhost_vring_call_reset(struct vhost_vring_call >>> *call_ctx) >>> +{ >>> + call_ctx->ctx = NULL; >>> + memset(&call_ctx->producer, 0x0, sizeof(struct >>> irq_bypass_producer)); >>> + spin_lock_init(&call_ctx->ctx_lock); >>> +} >>> + >>> static void vhost_vq_reset(struct vhost_dev *dev, >>> struct vhost_virtqueue *vq) >>> { >>> @@ -319,13 +326,13 @@ static void vhost_vq_reset(struct vhost_dev *dev, >>> vq->log_base = NULL; >>> vq->error_ctx = NULL; >>> vq->kick = NULL; >>> - vq->call_ctx = NULL; >>> vq->log_ctx = NULL; >>> vhost_reset_is_le(vq); >>> vhost_disable_cross_endian(vq); >>> vq->busyloop_timeout = 0; >>> vq->umem = NULL; >>> vq->iotlb = NULL; >>> + vhost_vring_call_reset(&vq->call_ctx); >>> __vhost_vq_meta_reset(vq); >>> } >>> @@ -685,8 +692,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev) >>> eventfd_ctx_put(dev->vqs[i]->error_ctx); >>> if (dev->vqs[i]->kick) >>> fput(dev->vqs[i]->kick); >>> - if (dev->vqs[i]->call_ctx) >>> - eventfd_ctx_put(dev->vqs[i]->call_ctx); >>> + if (dev->vqs[i]->call_ctx.ctx) >>> + eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx); >>> vhost_vq_reset(dev, dev->vqs[i]); >>> } >>> vhost_dev_free_iovecs(dev); >>> @@ -1629,7 +1636,10 @@ long vhost_vring_ioctl(struct vhost_dev *d, >>> unsigned int ioctl, void __user *arg >>> r = PTR_ERR(ctx); >>> break; >>> } >>> - swap(ctx, vq->call_ctx); >>> + >>> + spin_lock(&vq->call_ctx.ctx_lock); >>> + swap(ctx, vq->call_ctx.ctx); >>> + spin_unlock(&vq->call_ctx.ctx_lock); >>> break; >>> case VHOST_SET_VRING_ERR: >>> if (copy_from_user(&f, argp, sizeof f)) { >>> @@ -2440,8 +2450,8 @@ static bool vhost_notify(struct vhost_dev >>> *dev, struct vhost_virtqueue *vq) >>> void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) >>> { >>> /* Signal the Guest tell them we used something up. */ >>> - if (vq->call_ctx && vhost_notify(dev, vq)) >>> - eventfd_signal(vq->call_ctx, 1); >>> + if (vq->call_ctx.ctx && vhost_notify(dev, vq)) >>> + eventfd_signal(vq->call_ctx.ctx, 1); >>> } >>> EXPORT_SYMBOL_GPL(vhost_signal); >>> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h >>> index c8e96a095d3b..38eb1aa3b68d 100644 >>> --- a/drivers/vhost/vhost.h >>> +++ b/drivers/vhost/vhost.h >>> @@ -13,6 +13,7 @@ >>> #include <linux/virtio_ring.h> >>> #include <linux/atomic.h> >>> #include <linux/vhost_iotlb.h> >>> +#include <linux/irqbypass.h> >>> struct vhost_work; >>> typedef void (*vhost_work_fn_t)(struct vhost_work *work); >>> @@ -60,6 +61,12 @@ enum vhost_uaddr_type { >>> VHOST_NUM_ADDRS = 3, >>> }; >>> +struct vhost_vring_call { >>> + struct eventfd_ctx *ctx; >>> + struct irq_bypass_producer producer; >>> + spinlock_t ctx_lock; >> >> >> It's not clear to me why we need ctx_lock here. >> >> Thanks > Hi Jason, > > we use this lock to protect the eventfd_ctx and irq from race conditions, We don't support irq notification from vDPA device driver in this version, do we still have race condition? Thanks > are you suggesting a better name? > > Thanks >> >> >>> +}; >>> + >>> /* The virtqueue structure describes a queue attached to a device. */ >>> struct vhost_virtqueue { >>> struct vhost_dev *dev; >>> @@ -72,7 +79,7 @@ struct vhost_virtqueue { >>> vring_used_t __user *used; >>> const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS]; >>> struct file *kick; >>> - struct eventfd_ctx *call_ctx; >>> + struct vhost_vring_call call_ctx; >>> struct eventfd_ctx *error_ctx; >>> struct eventfd_ctx *log_ctx; >>
On Tue, Aug 04, 2020 at 04:53:39PM +0800, Jason Wang wrote: > > On 2020/8/4 下午4:42, Zhu, Lingshan wrote: > > > > > > On 8/4/2020 4:38 PM, Jason Wang wrote: > > > > > > On 2020/7/31 下午2:55, Zhu Lingshan wrote: > > > > This commit introduces struct vhost_vring_call which replaced > > > > raw struct eventfd_ctx *call_ctx in struct vhost_virtqueue. > > > > Besides eventfd_ctx, it contains a spin lock and an > > > > irq_bypass_producer in its structure. > > > > > > > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> > > > > Suggested-by: Jason Wang <jasowang@redhat.com> > > > > --- > > > > drivers/vhost/vdpa.c | 4 ++-- > > > > drivers/vhost/vhost.c | 22 ++++++++++++++++------ > > > > drivers/vhost/vhost.h | 9 ++++++++- > > > > 3 files changed, 26 insertions(+), 9 deletions(-) > > > > > > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > > > > index a54b60d6623f..df3cf386b0cd 100644 > > > > --- a/drivers/vhost/vdpa.c > > > > +++ b/drivers/vhost/vdpa.c > > > > @@ -96,7 +96,7 @@ static void handle_vq_kick(struct vhost_work *work) > > > > static irqreturn_t vhost_vdpa_virtqueue_cb(void *private) > > > > { > > > > struct vhost_virtqueue *vq = private; > > > > - struct eventfd_ctx *call_ctx = vq->call_ctx; > > > > + struct eventfd_ctx *call_ctx = vq->call_ctx.ctx; > > > > if (call_ctx) > > > > eventfd_signal(call_ctx, 1); > > > > @@ -382,7 +382,7 @@ static long vhost_vdpa_vring_ioctl(struct > > > > vhost_vdpa *v, unsigned int cmd, > > > > break; > > > > case VHOST_SET_VRING_CALL: > > > > - if (vq->call_ctx) { > > > > + if (vq->call_ctx.ctx) { > > > > cb.callback = vhost_vdpa_virtqueue_cb; > > > > cb.private = vq; > > > > } else { > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > > > index d7b8df3edffc..9f1a845a9302 100644 > > > > --- a/drivers/vhost/vhost.c > > > > +++ b/drivers/vhost/vhost.c > > > > @@ -298,6 +298,13 @@ static void vhost_vq_meta_reset(struct > > > > vhost_dev *d) > > > > __vhost_vq_meta_reset(d->vqs[i]); > > > > } > > > > +static void vhost_vring_call_reset(struct vhost_vring_call > > > > *call_ctx) > > > > +{ > > > > + call_ctx->ctx = NULL; > > > > + memset(&call_ctx->producer, 0x0, sizeof(struct > > > > irq_bypass_producer)); > > > > + spin_lock_init(&call_ctx->ctx_lock); > > > > +} > > > > + > > > > static void vhost_vq_reset(struct vhost_dev *dev, > > > > struct vhost_virtqueue *vq) > > > > { > > > > @@ -319,13 +326,13 @@ static void vhost_vq_reset(struct vhost_dev *dev, > > > > vq->log_base = NULL; > > > > vq->error_ctx = NULL; > > > > vq->kick = NULL; > > > > - vq->call_ctx = NULL; > > > > vq->log_ctx = NULL; > > > > vhost_reset_is_le(vq); > > > > vhost_disable_cross_endian(vq); > > > > vq->busyloop_timeout = 0; > > > > vq->umem = NULL; > > > > vq->iotlb = NULL; > > > > + vhost_vring_call_reset(&vq->call_ctx); > > > > __vhost_vq_meta_reset(vq); > > > > } > > > > @@ -685,8 +692,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev) > > > > eventfd_ctx_put(dev->vqs[i]->error_ctx); > > > > if (dev->vqs[i]->kick) > > > > fput(dev->vqs[i]->kick); > > > > - if (dev->vqs[i]->call_ctx) > > > > - eventfd_ctx_put(dev->vqs[i]->call_ctx); > > > > + if (dev->vqs[i]->call_ctx.ctx) > > > > + eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx); > > > > vhost_vq_reset(dev, dev->vqs[i]); > > > > } > > > > vhost_dev_free_iovecs(dev); > > > > @@ -1629,7 +1636,10 @@ long vhost_vring_ioctl(struct vhost_dev > > > > *d, unsigned int ioctl, void __user *arg > > > > r = PTR_ERR(ctx); > > > > break; > > > > } > > > > - swap(ctx, vq->call_ctx); > > > > + > > > > + spin_lock(&vq->call_ctx.ctx_lock); > > > > + swap(ctx, vq->call_ctx.ctx); > > > > + spin_unlock(&vq->call_ctx.ctx_lock); > > > > break; > > > > case VHOST_SET_VRING_ERR: > > > > if (copy_from_user(&f, argp, sizeof f)) { > > > > @@ -2440,8 +2450,8 @@ static bool vhost_notify(struct vhost_dev > > > > *dev, struct vhost_virtqueue *vq) > > > > void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) > > > > { > > > > /* Signal the Guest tell them we used something up. */ > > > > - if (vq->call_ctx && vhost_notify(dev, vq)) > > > > - eventfd_signal(vq->call_ctx, 1); > > > > + if (vq->call_ctx.ctx && vhost_notify(dev, vq)) > > > > + eventfd_signal(vq->call_ctx.ctx, 1); > > > > } > > > > EXPORT_SYMBOL_GPL(vhost_signal); > > > > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > > > > index c8e96a095d3b..38eb1aa3b68d 100644 > > > > --- a/drivers/vhost/vhost.h > > > > +++ b/drivers/vhost/vhost.h > > > > @@ -13,6 +13,7 @@ > > > > #include <linux/virtio_ring.h> > > > > #include <linux/atomic.h> > > > > #include <linux/vhost_iotlb.h> > > > > +#include <linux/irqbypass.h> > > > > struct vhost_work; > > > > typedef void (*vhost_work_fn_t)(struct vhost_work *work); > > > > @@ -60,6 +61,12 @@ enum vhost_uaddr_type { > > > > VHOST_NUM_ADDRS = 3, > > > > }; > > > > +struct vhost_vring_call { > > > > + struct eventfd_ctx *ctx; > > > > + struct irq_bypass_producer producer; > > > > + spinlock_t ctx_lock; > > > > > > > > > It's not clear to me why we need ctx_lock here. > > > > > > Thanks > > Hi Jason, > > > > we use this lock to protect the eventfd_ctx and irq from race conditions, > > > We don't support irq notification from vDPA device driver in this version, > do we still have race condition? > > Thanks Jason I'm not sure what you are trying to say here. > > > are you suggesting a better name? > > > > Thanks > > > > > > > > > > +}; > > > > + > > > > /* The virtqueue structure describes a queue attached to a device. */ > > > > struct vhost_virtqueue { > > > > struct vhost_dev *dev; > > > > @@ -72,7 +79,7 @@ struct vhost_virtqueue { > > > > vring_used_t __user *used; > > > > const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS]; > > > > struct file *kick; > > > > - struct eventfd_ctx *call_ctx; > > > > + struct vhost_vring_call call_ctx; > > > > struct eventfd_ctx *error_ctx; > > > > struct eventfd_ctx *log_ctx; > > >
On 2020/8/4 下午5:21, Michael S. Tsirkin wrote: >>>>> +struct vhost_vring_call { >>>>> + struct eventfd_ctx *ctx; >>>>> + struct irq_bypass_producer producer; >>>>> + spinlock_t ctx_lock; >>>> It's not clear to me why we need ctx_lock here. >>>> >>>> Thanks >>> Hi Jason, >>> >>> we use this lock to protect the eventfd_ctx and irq from race conditions, >> We don't support irq notification from vDPA device driver in this version, >> do we still have race condition? >> >> Thanks > Jason I'm not sure what you are trying to say here. I meant we change the API from V4 so driver won't notify us if irq is changed. Then it looks to me there's no need for the ctx_lock, everyhing could be synchronized with vq mutex. Thanks > >
On 2020/8/4 下午5:21, Zhu, Lingshan wrote: >>> Hi Jason, >>> >>> we use this lock to protect the eventfd_ctx and irq from race >>> conditions, >> >> >> We don't support irq notification from vDPA device driver in this >> version, do we still have race condition? > as we discussed before: > (1)if vendor change IRQ after DRIVER_OK, through they should not do this, but they can. > (2)if user space changes ctx. > > Thanks Yes, but then everything happens in context of syscall (ioctl), so vq mutex is sufficient I guess? Thanks
On 2020/8/5 下午1:49, Zhu, Lingshan wrote: > > > On 8/5/2020 10:16 AM, Jason Wang wrote: >> >> On 2020/8/4 下午5:21, Michael S. Tsirkin wrote: >>>>>>> +struct vhost_vring_call { >>>>>>> + struct eventfd_ctx *ctx; >>>>>>> + struct irq_bypass_producer producer; >>>>>>> + spinlock_t ctx_lock; >>>>>> It's not clear to me why we need ctx_lock here. >>>>>> >>>>>> Thanks >>>>> Hi Jason, >>>>> >>>>> we use this lock to protect the eventfd_ctx and irq from race >>>>> conditions, >>>> We don't support irq notification from vDPA device driver in this >>>> version, >>>> do we still have race condition? >>>> >>>> Thanks >>> Jason I'm not sure what you are trying to say here. >> >> >> I meant we change the API from V4 so driver won't notify us if irq is >> changed. >> >> Then it looks to me there's no need for the ctx_lock, everyhing could >> be synchronized with vq mutex. >> >> Thanks > from V4 to V5, there are only some minor improvements and bug fix, get_vq_irq() almost stays untouched, mutex can work for this, however I see the vq mutex is used in many scenarios. > We only use this lock to protect the producer information, can this help to get less coupling, defensive code for less bugs? I think not, vq mutex is used to protect all vq related data structure, introducing another one will increase the complexity. Thanks > > Thanks >> >>> >>> >>
On Wed, Aug 05, 2020 at 10:16:16AM +0800, Jason Wang wrote: > > On 2020/8/4 下午5:21, Michael S. Tsirkin wrote: > > > > > > +struct vhost_vring_call { > > > > > > + struct eventfd_ctx *ctx; > > > > > > + struct irq_bypass_producer producer; > > > > > > + spinlock_t ctx_lock; > > > > > It's not clear to me why we need ctx_lock here. > > > > > > > > > > Thanks > > > > Hi Jason, > > > > > > > > we use this lock to protect the eventfd_ctx and irq from race conditions, > > > We don't support irq notification from vDPA device driver in this version, > > > do we still have race condition? > > > > > > Thanks > > Jason I'm not sure what you are trying to say here. > > > I meant we change the API from V4 so driver won't notify us if irq is > changed. > > Then it looks to me there's no need for the ctx_lock, everyhing could be > synchronized with vq mutex. > > Thanks Jason do you want to post a cleanup patch simplifying code along these lines? Thanks, > > > >
On 2020/8/10 下午9:37, Michael S. Tsirkin wrote: > On Wed, Aug 05, 2020 at 10:16:16AM +0800, Jason Wang wrote: >> On 2020/8/4 下午5:21, Michael S. Tsirkin wrote: >>>>>>> +struct vhost_vring_call { >>>>>>> + struct eventfd_ctx *ctx; >>>>>>> + struct irq_bypass_producer producer; >>>>>>> + spinlock_t ctx_lock; >>>>>> It's not clear to me why we need ctx_lock here. >>>>>> >>>>>> Thanks >>>>> Hi Jason, >>>>> >>>>> we use this lock to protect the eventfd_ctx and irq from race conditions, >>>> We don't support irq notification from vDPA device driver in this version, >>>> do we still have race condition? >>>> >>>> Thanks >>> Jason I'm not sure what you are trying to say here. >> >> I meant we change the API from V4 so driver won't notify us if irq is >> changed. >> >> Then it looks to me there's no need for the ctx_lock, everyhing could be >> synchronized with vq mutex. >> >> Thanks > Jason do you want to post a cleanup patch simplifying code along these > lines? Ling Shan promised to post a patch to fix this. Thanks > > Thanks, > > >>>
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c index a54b60d6623f..df3cf386b0cd 100644 --- a/drivers/vhost/vdpa.c +++ b/drivers/vhost/vdpa.c @@ -96,7 +96,7 @@ static void handle_vq_kick(struct vhost_work *work) static irqreturn_t vhost_vdpa_virtqueue_cb(void *private) { struct vhost_virtqueue *vq = private; - struct eventfd_ctx *call_ctx = vq->call_ctx; + struct eventfd_ctx *call_ctx = vq->call_ctx.ctx; if (call_ctx) eventfd_signal(call_ctx, 1); @@ -382,7 +382,7 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, break; case VHOST_SET_VRING_CALL: - if (vq->call_ctx) { + if (vq->call_ctx.ctx) { cb.callback = vhost_vdpa_virtqueue_cb; cb.private = vq; } else { diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index d7b8df3edffc..9f1a845a9302 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -298,6 +298,13 @@ static void vhost_vq_meta_reset(struct vhost_dev *d) __vhost_vq_meta_reset(d->vqs[i]); } +static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx) +{ + call_ctx->ctx = NULL; + memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer)); + spin_lock_init(&call_ctx->ctx_lock); +} + static void vhost_vq_reset(struct vhost_dev *dev, struct vhost_virtqueue *vq) { @@ -319,13 +326,13 @@ static void vhost_vq_reset(struct vhost_dev *dev, vq->log_base = NULL; vq->error_ctx = NULL; vq->kick = NULL; - vq->call_ctx = NULL; vq->log_ctx = NULL; vhost_reset_is_le(vq); vhost_disable_cross_endian(vq); vq->busyloop_timeout = 0; vq->umem = NULL; vq->iotlb = NULL; + vhost_vring_call_reset(&vq->call_ctx); __vhost_vq_meta_reset(vq); } @@ -685,8 +692,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev) eventfd_ctx_put(dev->vqs[i]->error_ctx); if (dev->vqs[i]->kick) fput(dev->vqs[i]->kick); - if (dev->vqs[i]->call_ctx) - eventfd_ctx_put(dev->vqs[i]->call_ctx); + if (dev->vqs[i]->call_ctx.ctx) + eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx); vhost_vq_reset(dev, dev->vqs[i]); } vhost_dev_free_iovecs(dev); @@ -1629,7 +1636,10 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg r = PTR_ERR(ctx); break; } - swap(ctx, vq->call_ctx); + + spin_lock(&vq->call_ctx.ctx_lock); + swap(ctx, vq->call_ctx.ctx); + spin_unlock(&vq->call_ctx.ctx_lock); break; case VHOST_SET_VRING_ERR: if (copy_from_user(&f, argp, sizeof f)) { @@ -2440,8 +2450,8 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) { /* Signal the Guest tell them we used something up. */ - if (vq->call_ctx && vhost_notify(dev, vq)) - eventfd_signal(vq->call_ctx, 1); + if (vq->call_ctx.ctx && vhost_notify(dev, vq)) + eventfd_signal(vq->call_ctx.ctx, 1); } EXPORT_SYMBOL_GPL(vhost_signal); diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index c8e96a095d3b..38eb1aa3b68d 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -13,6 +13,7 @@ #include <linux/virtio_ring.h> #include <linux/atomic.h> #include <linux/vhost_iotlb.h> +#include <linux/irqbypass.h> struct vhost_work; typedef void (*vhost_work_fn_t)(struct vhost_work *work); @@ -60,6 +61,12 @@ enum vhost_uaddr_type { VHOST_NUM_ADDRS = 3, }; +struct vhost_vring_call { + struct eventfd_ctx *ctx; + struct irq_bypass_producer producer; + spinlock_t ctx_lock; +}; + /* The virtqueue structure describes a queue attached to a device. */ struct vhost_virtqueue { struct vhost_dev *dev; @@ -72,7 +79,7 @@ struct vhost_virtqueue { vring_used_t __user *used; const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS]; struct file *kick; - struct eventfd_ctx *call_ctx; + struct vhost_vring_call call_ctx; struct eventfd_ctx *error_ctx; struct eventfd_ctx *log_ctx;
This commit introduces struct vhost_vring_call which replaced raw struct eventfd_ctx *call_ctx in struct vhost_virtqueue. Besides eventfd_ctx, it contains a spin lock and an irq_bypass_producer in its structure. Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> Suggested-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/vdpa.c | 4 ++-- drivers/vhost/vhost.c | 22 ++++++++++++++++------ drivers/vhost/vhost.h | 9 ++++++++- 3 files changed, 26 insertions(+), 9 deletions(-)