From 27ebe308af7c14aed0711e25817c6a1235bd16ff Mon Sep 17 00:00:00 2001 From: Anthony Liguori Date: Sun, 2 Mar 2008 16:37:48 -0600 Subject: virtio: Use spin_lock_irqsave/restore for virtio-pci virtio-pci acquires its spin lock in an interrupt context so it's necessary to use spin_lock_irqsave/restore variants. This patch fixes guest SMP when using virtio devices in KVM. Signed-off-by: Anthony Liguori Signed-off-by: Rusty Russell --- drivers/virtio/virtio_pci.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index 26f787ddd5f..59a8f73dec7 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -177,6 +177,7 @@ static irqreturn_t vp_interrupt(int irq, void *opaque) struct virtio_pci_device *vp_dev = opaque; struct virtio_pci_vq_info *info; irqreturn_t ret = IRQ_NONE; + unsigned long flags; u8 isr; /* reading the ISR has the effect of also clearing it so it's very @@ -197,12 +198,12 @@ static irqreturn_t vp_interrupt(int irq, void *opaque) drv->config_changed(&vp_dev->vdev); } - spin_lock(&vp_dev->lock); + spin_lock_irqsave(&vp_dev->lock, flags); list_for_each_entry(info, &vp_dev->virtqueues, node) { if (vring_interrupt(irq, info->vq) == IRQ_HANDLED) ret = IRQ_HANDLED; } - spin_unlock(&vp_dev->lock); + spin_unlock_irqrestore(&vp_dev->lock, flags); return ret; } @@ -214,6 +215,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index, struct virtio_pci_device *vp_dev = to_vp_device(vdev); struct virtio_pci_vq_info *info; struct virtqueue *vq; + unsigned long flags; u16 num; int err; @@ -255,9 +257,9 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index, vq->priv = info; info->vq = vq; - spin_lock(&vp_dev->lock); + spin_lock_irqsave(&vp_dev->lock, flags); list_add(&info->node, &vp_dev->virtqueues); - spin_unlock(&vp_dev->lock); + spin_unlock_irqrestore(&vp_dev->lock, flags); return vq; @@ -274,10 +276,11 @@ static void vp_del_vq(struct virtqueue *vq) { struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev); struct virtio_pci_vq_info *info = vq->priv; + unsigned long flags; - spin_lock(&vp_dev->lock); + spin_lock_irqsave(&vp_dev->lock, flags); list_del(&info->node); - spin_unlock(&vp_dev->lock); + spin_unlock_irqrestore(&vp_dev->lock, flags); vring_del_virtqueue(vq); -- cgit v1.2.3 From c483934670d31e064e18967bb679c1079b54ea72 Mon Sep 17 00:00:00 2001 From: Jeremy Katz Date: Sun, 2 Mar 2008 17:00:15 -0500 Subject: virtio: Fix sysfs bits to have proper block symlink Fix up so that the virtio_blk devices in sysfs link correctly to their block device. This then allows them to be detected by hal, etc Signed-off-by: Jeremy Katz Signed-off-by: Rusty Russell --- drivers/block/virtio_blk.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 3b1a68d6edd..0cfbe8c594a 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -238,6 +238,7 @@ static int virtblk_probe(struct virtio_device *vdev) vblk->disk->first_minor = index_to_minor(index); vblk->disk->private_data = vblk; vblk->disk->fops = &virtblk_fops; + vblk->disk->driverfs_dev = &vdev->dev; index++; /* If barriers are supported, tell block layer that queue is ordered */ -- cgit v1.2.3 From bdc1681cdf1ab6a65fa935a2b3f8fc63b20c54ea Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 17 Mar 2008 22:58:15 -0500 Subject: virtio: handle > 2 billion page balloon targets If the host asks for a huge target towards_target() can overflow, and we up oops as we try to release more pages than we have. The simple fix is to use a 64-bit value. Signed-off-by: Rusty Russell --- drivers/virtio/virtio_balloon.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index c8a4332d113..0b3efc31ee6 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -152,7 +152,7 @@ static void virtballoon_changed(struct virtio_device *vdev) wake_up(&vb->config_change); } -static inline int towards_target(struct virtio_balloon *vb) +static inline s64 towards_target(struct virtio_balloon *vb) { u32 v; __virtio_config_val(vb->vdev, @@ -176,7 +176,7 @@ static int balloon(void *_vballoon) set_freezable(); while (!kthread_should_stop()) { - int diff; + s64 diff; try_to_freeze(); wait_event_interruptible(vb->config_change, -- cgit v1.2.3 From da74e89d40995600b3b07ac500084920247687ce Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Fri, 29 Feb 2008 16:24:50 +0530 Subject: virtio: Enable netpoll interface for netconsole logging Add a new poll_controller handler that the netpoll interface needs. This enables netconsole logging from a kvm guest over the virtio net interface. Signed-off-by: Amit Shah Signed-off-by: Rusty Russell --- drivers/net/virtio_net.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 19fd4cb0ddf..e575df83e5c 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -294,6 +294,15 @@ again: return 0; } +#ifdef CONFIG_NET_POLL_CONTROLLER +static void virtnet_netpoll(struct net_device *dev) +{ + struct virtnet_info *vi = netdev_priv(dev); + + napi_schedule(&vi->napi); +} +#endif + static int virtnet_open(struct net_device *dev) { struct virtnet_info *vi = netdev_priv(dev); @@ -336,6 +345,9 @@ static int virtnet_probe(struct virtio_device *vdev) dev->stop = virtnet_close; dev->hard_start_xmit = start_xmit; dev->features = NETIF_F_HIGHDMA; +#ifdef CONFIG_NET_POLL_CONTROLLER + dev->poll_controller = virtnet_netpoll; +#endif SET_NETDEV_DEV(dev, &vdev->dev); /* Do we support "hardware" checksums? */ -- cgit v1.2.3 From 4265f161b6bb7b31163671329b1142b9023bf4e3 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 14 Mar 2008 14:17:05 +0100 Subject: virtio: fix race in enable_cb There is a race in virtio_net, dealing with disabling/enabling the callback. I saw the following oops: kernel BUG at /space/kvm/drivers/virtio/virtio_ring.c:218! illegal operation: 0001 [#1] SMP Modules linked in: sunrpc dm_mod CPU: 2 Not tainted 2.6.25-rc1zlive-host-10623-gd358142-dirty #99 Process swapper (pid: 0, task: 000000000f85a610, ksp: 000000000f873c60) Krnl PSW : 0404300180000000 00000000002b81a6 (vring_disable_cb+0x16/0x20) R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:3 PM:0 EA:3 Krnl GPRS: 0000000000000001 0000000000000001 0000000010005800 0000000000000001 000000000f3a0900 000000000f85a610 0000000000000000 0000000000000000 0000000000000000 000000000f870000 0000000000000000 0000000000001237 000000000f3a0920 000000000010ff74 00000000002846f6 000000000fa0bcd8 Krnl Code: 00000000002b819a: a7110001 tmll %r1,1 00000000002b819e: a7840004 brc 8,2b81a6 00000000002b81a2: a7f40001 brc 15,2b81a4 >00000000002b81a6: a51b0001 oill %r1,1 00000000002b81aa: 40102000 sth %r1,0(%r2) 00000000002b81ae: 07fe bcr 15,%r14 00000000002b81b0: eb7ff0380024 stmg %r7,%r15,56(%r15) 00000000002b81b6: a7f13e00 tmll %r15,15872 Call Trace: ([<000000000fa0bcd0>] 0xfa0bcd0) [<00000000002b8350>] vring_interrupt+0x5c/0x6c [<000000000010ab08>] do_extint+0xb8/0xf0 [<0000000000110716>] ext_no_vtime+0x16/0x1a [<0000000000107e72>] cpu_idle+0x1c2/0x1e0 The problem can be triggered with a high amount of host->guest traffic. I think its the following race: poll says netif_rx_complete poll calls enable_cb enable_cb opens the interrupt mask a new packet comes, an interrupt is triggered----\ enable_cb sees that there is more work | enable_cb disables the interrupt | . V . interrupt is delivered . skb_recv_done does atomic napi test, ok some waiting disable_cb is called->check fails->bang! . poll would do napi check poll would do disable_cb The fix is to let enable_cb not disable the interrupt again, but expect the caller to do the cleanup if it returns false. In that case, the interrupt is only disabled, if the napi test_set_bit was successful. Signed-off-by: Christian Borntraeger Signed-off-by: Rusty Russell (cleaned up doco) --- drivers/net/virtio_net.c | 10 +++++++--- drivers/virtio/virtio_ring.c | 1 - include/linux/virtio.h | 5 +++-- 3 files changed, 10 insertions(+), 6 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index e575df83e5c..b58472cf76f 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -203,8 +203,11 @@ again: if (received < budget) { netif_rx_complete(vi->dev, napi); if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq)) - && netif_rx_reschedule(vi->dev, napi)) + && napi_schedule_prep(napi)) { + vi->rvq->vq_ops->disable_cb(vi->rvq); + __netif_rx_schedule(vi->dev, napi); goto again; + } } return received; @@ -278,10 +281,11 @@ again: pr_debug("%s: virtio not prepared to send\n", dev->name); netif_stop_queue(dev); - /* Activate callback for using skbs: if this fails it + /* Activate callback for using skbs: if this returns false it * means some were used in the meantime. */ if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) { - printk("Unlikely: restart svq failed\n"); + printk("Unlikely: restart svq race\n"); + vi->svq->vq_ops->disable_cb(vi->svq); netif_start_queue(dev); goto again; } diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 3a28c138213..aa714028641 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -232,7 +232,6 @@ static bool vring_enable_cb(struct virtqueue *_vq) vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; mb(); if (unlikely(more_used(vq))) { - vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; END_USE(vq); return false; } diff --git a/include/linux/virtio.h b/include/linux/virtio.h index 260d1fcf29a..12c18ac1b97 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -43,8 +43,9 @@ struct virtqueue * vq: the struct virtqueue we're talking about. * @enable_cb: restart callbacks after disable_cb. * vq: the struct virtqueue we're talking about. - * This returns "false" (and doesn't re-enable) if there are pending - * buffers in the queue, to avoid a race. + * This re-enables callbacks; it returns "false" if there are pending + * buffers in the queue, to detect a possible race between the driver + * checking for more work, and enabling callbacks. * * Locking rules are straightforward: the driver is responsible for * locking. No two operations may be invoked simultaneously. -- cgit v1.2.3