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Wed, 15 Jul 2020 08:52:11 +0000 (UTC) Received: from [10.72.13.230] (ovpn-13-230.pek2.redhat.com [10.72.13.230]) by smtp.corp.redhat.com (Postfix) with ESMTP id BB86D7950C; Wed, 15 Jul 2020 08:51:47 +0000 (UTC) Subject: Re: [PATCH 3/7] vhost_vdpa: implement IRQ offloading functions in vhost_vdpa To: "Zhu, Lingshan" , mst@redhat.com, alex.williamson@redhat.com, pbonzini@redhat.com, sean.j.christopherson@intel.com, wanpengli@tencent.com Cc: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, netdev@vger.kernel.org, dan.daly@intel.com References: <1594565366-3195-1-git-send-email-lingshan.zhu@intel.com> <1594565366-3195-3-git-send-email-lingshan.zhu@intel.com> <3fb9ecfc-a325-69b5-f5b7-476a5683a324@redhat.com> From: Jason Wang Message-ID: Date: Wed, 15 Jul 2020 16:51:46 +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 10.5.11.14 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2020/7/13 下午5:47, Zhu, Lingshan wrote: > > > On 7/13/2020 4:22 PM, Jason Wang wrote: >> >> On 2020/7/12 下午10:49, Zhu Lingshan wrote: >>> This patch introduce a set of functions for setup/unsetup >>> and update irq offloading respectively by register/unregister >>> and re-register the irq_bypass_producer. >>> >>> Signed-off-by: Zhu Lingshan >>> --- >>>   drivers/vhost/vdpa.c | 69 >>> ++++++++++++++++++++++++++++++++++++++++++++++++++++ >>>   1 file changed, 69 insertions(+) >>> >>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c >>> index 2fcc422..92683e4 100644 >>> --- a/drivers/vhost/vdpa.c >>> +++ b/drivers/vhost/vdpa.c >>> @@ -115,6 +115,63 @@ static irqreturn_t vhost_vdpa_config_cb(void >>> *private) >>>       return IRQ_HANDLED; >>>   } >>>   +static void vhost_vdpa_setup_vq_irq(struct vdpa_device *dev, int >>> qid, int irq) >>> +{ >>> +    struct vhost_vdpa *v = vdpa_get_drvdata(dev); >>> +    struct vhost_virtqueue *vq = &v->vqs[qid]; >>> +    int ret; >>> + >>> +    vq_err(vq, "setup irq bypass for vq %d with irq = %d\n", qid, >>> irq); >>> +    spin_lock(&vq->call_ctx.ctx_lock); >>> +    if (!vq->call_ctx.ctx) >>> +        return; >>> + >>> +    vq->call_ctx.producer.token = vq->call_ctx.ctx; >>> +    vq->call_ctx.producer.irq = irq; >>> +    ret = irq_bypass_register_producer(&vq->call_ctx.producer); >>> +    spin_unlock(&vq->call_ctx.ctx_lock); >>> + >>> +    if (unlikely(ret)) >>> +        vq_err(vq, >>> +        "irq bypass producer (token %p registration fails: %d\n", >>> +        vq->call_ctx.producer.token, ret); >> >> >> Not sure this deserves a vq_err(), irq will be relayed through >> eventfd if irq bypass manager can't work. > OK, I see vq_err() will eventfd_signal err_ctx than just print a > message, will remove all vq_err(). >> >> >>> +} >>> + >>> +static void vhost_vdpa_unsetup_vq_irq(struct vdpa_device *dev, int >>> qid) >>> +{ >>> +    struct vhost_vdpa *v = vdpa_get_drvdata(dev); >>> +    struct vhost_virtqueue *vq = &v->vqs[qid]; >>> + >>> +    spin_lock(&vq->call_ctx.ctx_lock); >>> + irq_bypass_unregister_producer(&vq->call_ctx.producer); >>> +    spin_unlock(&vq->call_ctx.ctx_lock); >>> + >>> +    vq_err(vq, "unsetup irq bypass for vq %d\n", qid); >> >> >> Why call vq_err() here? >> >> >>> +} >>> + >>> +static void vhost_vdpa_update_vq_irq(struct vhost_virtqueue *vq) >>> +{ >>> +    struct eventfd_ctx *ctx; >>> +    void *token; >>> + >>> +    spin_lock(&vq->call_ctx.ctx_lock); >>> +    ctx = vq->call_ctx.ctx; >>> +    token = vq->call_ctx.producer.token; >>> +    if (ctx == token) >>> +        return; >> >> >> Need do unlock here. > sure! >> >> >>> + >>> +    if (!ctx && token) >>> + irq_bypass_unregister_producer(&vq->call_ctx.producer); >>> + >>> +    if (ctx && ctx != token) { >>> + irq_bypass_unregister_producer(&vq->call_ctx.producer); >>> +        vq->call_ctx.producer.token = ctx; >>> + irq_bypass_register_producer(&vq->call_ctx.producer); >>> +    } >>> + >>> +    spin_unlock(&vq->call_ctx.ctx_lock); >> >> >> This should be rare so I'd use simple codes just do unregister and >> register. > > do you mean remove "if (ctx && ctx != token)"? I think this could be > useful, we should only update it when ctx!=NULL and ctx!= existing token. > I meant something like: unregister(); vq->call_ctx.producer.token = ctx; register(); >> >> >>> +} >>> + >>>   static void vhost_vdpa_reset(struct vhost_vdpa *v) >>>   { >>>       struct vdpa_device *vdpa = v->vdpa; >>> @@ -332,6 +389,7 @@ static long vhost_vdpa_set_config_call(struct >>> vhost_vdpa *v, u32 __user *argp) >>>         return 0; >>>   } >>> + >> >> >> Unnecessary change. > this new blank line is added because there is no blank line between > functions, I will double check The point is not mixing coding style fix with other fixes or enhancement. Thanks > THanks, BR Zhu Lingshan >> >> >>>   static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned >>> int cmd, >>>                      void __user *argp) >>>   { >>> @@ -390,6 +448,16 @@ static long vhost_vdpa_vring_ioctl(struct >>> vhost_vdpa *v, unsigned int cmd, >>>               cb.private = NULL; >>>           } >>>           ops->set_vq_cb(vdpa, idx, &cb); >>> +#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS >>> +        /* >>> +         * if it has a non-zero irq, means there is a >>> +         * previsouly registered irq_bypass_producer, >>> +         * we should update it when ctx (its token) >>> +         * changes. >>> +         */ >>> +        if (vq->call_ctx.producer.irq) >>> +            vhost_vdpa_update_vq_irq(vq); >>> +#endif >>>           break; >>>         case VHOST_SET_VRING_NUM: >>> @@ -741,6 +809,7 @@ static int vhost_vdpa_open(struct inode *inode, >>> struct file *filep) >>>           vqs[i] = &v->vqs[i]; >>>           vqs[i]->handle_kick = handle_vq_kick; >>>       } >>> + >> >> >> Unnecessary change. >> >> Thanks >> >> >>>       vhost_dev_init(dev, vqs, nvqs, 0, 0, 0, false, >>>                  vhost_vdpa_process_iotlb_msg); >>