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Tue, 4 Aug 2020 08:53:57 +0000 (UTC) Received: from [10.72.13.197] (ovpn-13-197.pek2.redhat.com [10.72.13.197]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5C1787178E; Tue, 4 Aug 2020 08:53:41 +0000 (UTC) Subject: Re: [PATCH V5 1/6] vhost: introduce vhost_vring_call To: "Zhu, Lingshan" , alex.williamson@redhat.com, mst@redhat.com, pbonzini@redhat.com, sean.j.christopherson@intel.com, wanpengli@tencent.com Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, eli@mellanox.com, shahafs@mellanox.com, parav@mellanox.com References: <20200731065533.4144-1-lingshan.zhu@intel.com> <20200731065533.4144-2-lingshan.zhu@intel.com> <5e646141-ca8d-77a5-6f41-d30710d91e6d@redhat.com> From: Jason Wang Message-ID: <156b8d71-6870-c163-fdfa-35bf4701987d@redhat.com> Date: Tue, 4 Aug 2020 16:53:39 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 >>> Suggested-by: Jason Wang >>> --- >>>   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 >>>   #include >>>   #include >>> +#include >>>     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; >>