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Wed, 15 Jul 2020 09:06:48 +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 C1EAA74F71; Wed, 15 Jul 2020 09:06:38 +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> <8f52ee3a-7a08-db14-9194-8085432481a4@intel.com> From: Jason Wang Message-ID: <2bd946e3-1524-efa5-df2b-3f6da66d2069@redhat.com> Date: Wed, 15 Jul 2020 17:06:36 +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: <8f52ee3a-7a08-db14-9194-8085432481a4@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2020/7/15 下午4:56, Zhu, Lingshan wrote: > > > On 7/15/2020 4:51 PM, Jason Wang wrote: >> >> 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(); > This is what we are doing now, or I must missed somethig: > 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); > > } > > It just unregister and register. I meant there's probably no need for the check and another check and unregister before. The whole function is as simple as I suggested above. Thanks > > Thanks, > BR > Zhu Lingshan