Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752070AbaKFJzs (ORCPT ); Thu, 6 Nov 2014 04:55:48 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:2097 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752005AbaKFJzn (ORCPT ); Thu, 6 Nov 2014 04:55:43 -0500 Message-ID: <545B456E.5050308@huawei.com> Date: Thu, 6 Nov 2014 17:54:54 +0800 From: Shannon Zhao User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: , , , , , , , , , Subject: Re: [RFC PATCH] virtio-mmio: support for multiple irqs References: <1415093712-15156-1-git-send-email-zhaoshenglong@huawei.com> <20141106093448.GA15417@redhat.com> In-Reply-To: <20141106093448.GA15417@redhat.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.16.142] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020206.545B457D.0039,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 2861ad683b822a2148dc389ccaad509c Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/11/6 17:34, Michael S. Tsirkin wrote: > On Tue, Nov 04, 2014 at 05:35:12PM +0800, Shannon Zhao wrote: >> As the current virtio-mmio only support single irq, >> so some advanced features such as vhost-net with irqfd >> are not supported. And the net performance is not >> the best without vhost-net and irqfd supporting. >> >> This patch support virtio-mmio to request multiple >> irqs like virtio-pci. With this patch and qemu assigning >> multiple irqs for virtio-mmio device, it's ok to use >> vhost-net with irqfd on arm/arm64. >> >> As arm doesn't support msi-x now, we use GSI for >> multiple irq. In this patch we use "vm_try_to_find_vqs" >> to check whether multiple irqs are supported like >> virtio-pci. >> >> Is this the right direction? is there other ways to >> make virtio-mmio support multiple irq? Hope for feedback. >> Thanks. >> >> Signed-off-by: Shannon Zhao > > > So how does guest discover whether host device supports multiple IRQs? Guest uses vm_try_to_find_vqs to check whether it can get multiple IRQs like virtio-pci uses vp_try_to_find_vqs. And within function vm_request_multiple_irqs, guest check whether the number of IRQs host device gives is equal to the number we want. for (i = 0; i < nirqs; i++) { irq = platform_get_irq(vm_dev->pdev, i); if (irq == -ENXIO) goto error; } If we can't get the expected number of IRQs, return error and this try fails. Then guest will try two IRQS and single IRQ like virtio-pci. > Could you please document the new interface? > E.g. send a patch for virtio spec. Ok, I'll send it later. Thank you very much :) Shannon > I think this really should be controlled by hypervisor, per device. > I'm also tempted to make this a virtio 1.0 only feature. > > > >> --- >> drivers/virtio/virtio_mmio.c | 234 ++++++++++++++++++++++++++++++++++++------ >> 1 files changed, 203 insertions(+), 31 deletions(-) >> >> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c >> index c600ccf..2b7d935 100644 >> --- a/drivers/virtio/virtio_mmio.c >> +++ b/drivers/virtio/virtio_mmio.c >> @@ -122,6 +122,15 @@ struct virtio_mmio_device { >> /* a list of queues so we can dispatch IRQs */ >> spinlock_t lock; >> struct list_head virtqueues; >> + >> + /* multiple irq support */ >> + int single_irq_enabled; >> + /* Number of available irqs */ >> + unsigned num_irqs; >> + /* Used number of irqs */ >> + int used_irqs; >> + /* Name strings for interrupts. */ >> + char (*vm_vq_names)[256]; >> }; >> >> struct virtio_mmio_vq_info { >> @@ -229,33 +238,53 @@ static bool vm_notify(struct virtqueue *vq) >> return true; >> } >> >> +/* Handle a configuration change: Tell driver if it wants to know. */ >> +static irqreturn_t vm_config_changed(int irq, void *opaque) >> +{ >> + struct virtio_mmio_device *vm_dev = opaque; >> + struct virtio_driver *vdrv = container_of(vm_dev->vdev.dev.driver, >> + struct virtio_driver, driver); >> + >> + if (vdrv && vdrv->config_changed) >> + vdrv->config_changed(&vm_dev->vdev); >> + return IRQ_HANDLED; >> +} >> + >> /* Notify all virtqueues on an interrupt. */ >> -static irqreturn_t vm_interrupt(int irq, void *opaque) >> +static irqreturn_t vm_vring_interrupt(int irq, void *opaque) >> { >> struct virtio_mmio_device *vm_dev = opaque; >> struct virtio_mmio_vq_info *info; >> - struct virtio_driver *vdrv = container_of(vm_dev->vdev.dev.driver, >> - struct virtio_driver, driver); >> - unsigned long status; >> + irqreturn_t ret = IRQ_NONE; >> unsigned long flags; >> + >> + spin_lock_irqsave(&vm_dev->lock, flags); >> + list_for_each_entry(info, &vm_dev->virtqueues, node) { >> + if (vring_interrupt(irq, info->vq) == IRQ_HANDLED) >> + ret = IRQ_HANDLED; >> + } >> + spin_unlock_irqrestore(&vm_dev->lock, flags); >> + >> + return ret; >> +} >> + >> +/* Notify all virtqueues and handle a configuration >> + * change on an interrupt. */ >> +static irqreturn_t vm_interrupt(int irq, void *opaque) >> +{ >> + struct virtio_mmio_device *vm_dev = opaque; >> + unsigned long status; >> irqreturn_t ret = IRQ_NONE; >> >> /* Read and acknowledge interrupts */ >> status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS); >> writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK); >> >> - if (unlikely(status & VIRTIO_MMIO_INT_CONFIG) >> - && vdrv && vdrv->config_changed) { >> - vdrv->config_changed(&vm_dev->vdev); >> - ret = IRQ_HANDLED; >> - } >> + if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)) >> + return vm_config_changed(irq, opaque); >> >> - if (likely(status & VIRTIO_MMIO_INT_VRING)) { >> - spin_lock_irqsave(&vm_dev->lock, flags); >> - list_for_each_entry(info, &vm_dev->virtqueues, node) >> - ret |= vring_interrupt(irq, info->vq); >> - spin_unlock_irqrestore(&vm_dev->lock, flags); >> - } >> + if (likely(status & VIRTIO_MMIO_INT_VRING)) >> + return vm_vring_interrupt(irq, opaque); >> >> return ret; >> } >> @@ -284,18 +313,98 @@ static void vm_del_vq(struct virtqueue *vq) >> kfree(info); >> } >> >> -static void vm_del_vqs(struct virtio_device *vdev) >> +static void vm_free_irqs(struct virtio_device *vdev) >> { >> + int i; >> struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev); >> + >> + if (vm_dev->single_irq_enabled) { >> + free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev); >> + vm_dev->single_irq_enabled = 0; >> + } >> + >> + for (i = 0; i < vm_dev->used_irqs; ++i) >> + free_irq(platform_get_irq(vm_dev->pdev, i), vm_dev); >> + >> + vm_dev->num_irqs = 0; >> + vm_dev->used_irqs = 0; >> + kfree(vm_dev->vm_vq_names); >> + vm_dev->vm_vq_names = NULL; >> +} >> + >> +static void vm_del_vqs(struct virtio_device *vdev) >> +{ >> struct virtqueue *vq, *n; >> >> list_for_each_entry_safe(vq, n, &vdev->vqs, list) >> vm_del_vq(vq); >> >> - free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev); >> + vm_free_irqs(vdev); >> +} >> + >> +static int vm_request_multiple_irqs(struct virtio_device *vdev, int nirqs, >> + bool per_vq_irq) >> +{ >> + int err = -ENOMEM; >> + struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev); >> + unsigned i, v; >> + int irq = 0; >> + >> + vm_dev->num_irqs = nirqs; >> + vm_dev->used_irqs = 0; >> + >> + vm_dev->vm_vq_names = kmalloc_array(nirqs, sizeof(*vm_dev->vm_vq_names), >> + GFP_KERNEL); >> + if (!vm_dev->vm_vq_names) >> + goto error; >> + >> + for (i = 0; i < nirqs; i++) { >> + irq = platform_get_irq(vm_dev->pdev, i); >> + if (irq == -ENXIO) >> + goto error; >> + } >> + >> + /* Set the irq used for configuration */ >> + v = vm_dev->used_irqs; >> + snprintf(vm_dev->vm_vq_names[v], sizeof(*vm_dev->vm_vq_names), >> + "%s-config", dev_name(&vdev->dev)); >> + irq = platform_get_irq(vm_dev->pdev, v); >> + err = request_irq(irq, vm_config_changed, 0, >> + vm_dev->vm_vq_names[v], vm_dev); >> + ++vm_dev->used_irqs; >> + if (err) >> + goto error; >> + >> + if (!per_vq_irq) { >> + /* Shared irq for all VQs */ >> + v = vm_dev->used_irqs; >> + snprintf(vm_dev->vm_vq_names[v], sizeof(*vm_dev->vm_vq_names), >> + "%s-virtqueues", dev_name(&vdev->dev)); >> + irq = platform_get_irq(vm_dev->pdev, v); >> + err = request_irq(irq, vm_vring_interrupt, 0, >> + vm_dev->vm_vq_names[v], vm_dev); >> + if (err) >> + goto error; >> + ++vm_dev->used_irqs; >> + } >> + return 0; >> +error: >> + vm_free_irqs(vdev); >> + return err; >> } >> >> +static int vm_request_single_irq(struct virtio_device *vdev) >> +{ >> + int err; >> + struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev); >> + int irq = platform_get_irq(vm_dev->pdev, 0); >> >> + err = request_irq(irq, vm_interrupt, IRQF_SHARED, >> + dev_name(&vdev->dev), vm_dev); >> + if (!err) >> + vm_dev->single_irq_enabled = 1; >> + return err; >> +} >> >> static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index, >> void (*callback)(struct virtqueue *vq), >> @@ -392,29 +501,92 @@ error_available: >> return ERR_PTR(err); >> } >> >> -static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs, >> - struct virtqueue *vqs[], >> - vq_callback_t *callbacks[], >> - const char *names[]) >> +static int vm_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs, >> + struct virtqueue *vqs[], >> + vq_callback_t *callbacks[], >> + const char *names[], >> + bool use_multiple_irq, >> + bool per_vq_irq) >> { >> struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev); >> - unsigned int irq = platform_get_irq(vm_dev->pdev, 0); >> - int i, err; >> + int i, err, nirqs, irq; >> + >> + if (!use_multiple_irq) { >> + /* Old style: one normal interrupt for change and all vqs. */ >> + err = vm_request_single_irq(vdev); >> + if (err) >> + goto error_request; >> + } else { >> + if (per_vq_irq) { >> + /* Best option: one for change interrupt, one per vq. */ >> + nirqs = 1; >> + for (i = 0; i < nvqs; ++i) >> + if (callbacks[i]) >> + ++nirqs; >> + } else { >> + /* Second best: one for change, shared for all vqs. */ >> + nirqs = 2; >> + } >> >> - err = request_irq(irq, vm_interrupt, IRQF_SHARED, >> - dev_name(&vdev->dev), vm_dev); >> - if (err) >> - return err; >> + err = vm_request_multiple_irqs(vdev, nirqs, per_vq_irq); >> + if (err) >> + goto error_request; >> + } >> >> - for (i = 0; i < nvqs; ++i) { >> + for (i = 0; i < nvqs; i++) { >> + if (!names[i]) { >> + vqs[i] = NULL; >> + continue; >> + } >> vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]); >> if (IS_ERR(vqs[i])) { >> - vm_del_vqs(vdev); >> - return PTR_ERR(vqs[i]); >> + err = PTR_ERR(vqs[i]); >> + goto error_find; >> + } >> + if (!per_vq_irq || !callbacks[i]) >> + continue; >> + /* allocate per-vq irq if available and necessary */ >> + snprintf(vm_dev->vm_vq_names[vm_dev->used_irqs], >> + sizeof(*vm_dev->vm_vq_names), >> + "%s-%s", >> + dev_name(&vm_dev->vdev.dev), names[i]); >> + irq = platform_get_irq(vm_dev->pdev, vm_dev->used_irqs); >> + err = request_irq(irq, vring_interrupt, 0, >> + vm_dev->vm_vq_names[vm_dev->used_irqs], vqs[i]); >> + if (err) { >> + vm_del_vq(vqs[i]); >> + goto error_find; >> } >> + ++vm_dev->used_irqs; >> } >> - >> return 0; >> +error_find: >> + vm_del_vqs(vdev); >> + >> +error_request: >> + return err; >> +} >> + >> +static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs, >> + struct virtqueue *vqs[], >> + vq_callback_t *callbacks[], >> + const char *names[]) >> +{ >> + int err; >> + >> + /* Try multiple irqs with one irq per queue. */ >> + err = vm_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, true, true); >> + if (!err) >> + return 0; >> + /* Fallback: multiple irqs with one irq for config, >> + * one shared for queues. */ >> + err = vm_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, >> + true, false); >> + if (!err) >> + return 0; >> + /* Finally fall back to regular single interrupts. */ >> + return vm_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, >> + false, false); >> } >> >> static const char *vm_bus_name(struct virtio_device *vdev) >> -- >> 1.7.1 > > . > -- Shannon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/