Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751184AbaKFLJ7 (ORCPT ); Thu, 6 Nov 2014 06:09:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37494 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750902AbaKFLJ5 (ORCPT ); Thu, 6 Nov 2014 06:09:57 -0500 Date: Thu, 6 Nov 2014 13:09:29 +0200 From: "Michael S. Tsirkin" To: Shannon Zhao Cc: linux-kernel@vger.kernel.org, peter.maydell@linaro.org, john.liuli@huawei.com, joel.schopp@amd.com, remy.gauguey@cea.fr, qemu-devel@nongnu.org, n.nikolaev@virtualopensystems.com, virtualization@lists.linux-foundation.org, peter.huangpeng@huawei.com, hangaohuai@huawei.com Subject: Re: [RFC PATCH] virtio-mmio: support for multiple irqs Message-ID: <20141106110929.GA16309@redhat.com> References: <1415093712-15156-1-git-send-email-zhaoshenglong@huawei.com> <20141106093448.GA15417@redhat.com> <545B456E.5050308@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <545B456E.5050308@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 06, 2014 at 05:54:54PM +0800, Shannon Zhao wrote: > 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. OK but how does host specify the number of IRQs for a device? for pci this is done through the MSI-X capability register. > 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/