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[Qemu-devel] Re: [PATCH] [STABLE] Fix virtio-blk hot add after remove
From: |
Dustin Kirkland |
Subject: |
[Qemu-devel] Re: [PATCH] [STABLE] Fix virtio-blk hot add after remove |
Date: |
Wed, 14 Oct 2009 13:22:16 -0500 |
On Wed, 2009-10-14 at 11:59 -0500, Anthony Liguori wrote:
> qdev_init_bdrv() expects that each drive added is the next logical unit for
> the given interface type. However, when dealing with hotplug, there may
> be holes in the units. drive_init reclaims holes in units but
> qdev_init_bdrv()
> is not smart enough to do this.
>
> Fortunately, in master, this has all been rewritten so for stable, let's hack
> around this a bit. To fix this, we need to tell qdev that a device has been
> removed so that it can keep track of which units are allocated. The only way
> we can get a hook for this though is to attach to the pci uninit callback. In
> order for virtio-blk to get this, another uninit callback needs to be added to
> the virtio layer.
>
> Suggestions for a less ugly solution are appreciated.
>
> This fixes https://bugs.launchpad.net/bugs/419590
>
> Signed-off-by: Anthony Liguori <address@hidden>
> ---
> hw/qdev.c | 33 ++++++++++++++++++++++++++++++---
> hw/virtio-blk.c | 8 ++++++++
> hw/virtio-pci.c | 19 ++++++++++++++++++-
> hw/virtio.h | 1 +
> sysemu.h | 2 ++
> 5 files changed, 59 insertions(+), 4 deletions(-)
>
> diff --git a/hw/qdev.c b/hw/qdev.c
> index faecc76..af60e3e 100644
> --- a/hw/qdev.c
> +++ b/hw/qdev.c
> @@ -181,21 +181,48 @@ void qdev_get_macaddr(DeviceState *dev, uint8_t
> *macaddr)
> memcpy(macaddr, dev->nd->macaddr, 6);
> }
>
> -static int next_block_unit[IF_COUNT];
> +typedef struct BlockUnitState
> +{
> + BlockDriverState *bs[32];
> +} BlockUnitState;
> +static BlockUnitState next_block_unit[IF_COUNT];
>
> /* Get a block device. This should only be used for single-drive devices
> (e.g. SD/Floppy/MTD). Multi-disk devices (scsi/ide) should use the
> appropriate bus. */
> BlockDriverState *qdev_init_bdrv(DeviceState *dev, BlockInterfaceType type)
> {
> - int unit = next_block_unit[type]++;
> + BlockDriverState *bs;
> + int unit;
> int index;
>
> + unit = 0;
> + while (next_block_unit[type].bs[unit]) {
> + unit++;
> + }
> +
> index = drive_get_index(type, 0, unit);
> if (index == -1) {
> return NULL;
> }
> - return drives_table[index].bdrv;
> +
> + bs = drives_table[index].bdrv;
> + next_block_unit[type].bs[unit] = bs;
> +
> + return bs;
> +}
> +
> +void qdev_uninit_bdrv(BlockDriverState *bs, BlockInterfaceType type)
> +{
> + int unit;
> +
> + for (unit = 0; unit < 32; unit++) {
> + if (next_block_unit[type].bs[unit] == bs) {
> + break;
> + }
> + }
> +
> + next_block_unit[type].bs[unit] = NULL;
> }
>
> BusState *qdev_get_child_bus(DeviceState *dev, const char *name)
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index 5036b5b..4bc11e6 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -414,6 +414,13 @@ static int virtio_blk_load(QEMUFile *f, void *opaque,
> int version_id)
> return 0;
> }
>
> +static void virtio_blk_uninit(VirtIODevice *vdev)
> +{
> + VirtIOBlock *s = to_virtio_blk(vdev);
> +
> + qdev_uninit_bdrv(s->bs, IF_VIRTIO);
> +}
> +
> VirtIODevice *virtio_blk_init(DeviceState *dev)
> {
> VirtIOBlock *s;
> @@ -430,6 +437,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev)
> s->vdev.get_config = virtio_blk_update_config;
> s->vdev.get_features = virtio_blk_get_features;
> s->vdev.reset = virtio_blk_reset;
> + s->vdev.uninit = virtio_blk_uninit;
> s->bs = bs;
> s->rq = NULL;
> if (strlen(ps = (char *)drive_get_serial(bs)))
> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> index 703f4fe..00b3998 100644
> --- a/hw/virtio-pci.c
> +++ b/hw/virtio-pci.c
> @@ -375,6 +375,22 @@ static const VirtIOBindings virtio_pci_bindings = {
> .load_queue = virtio_pci_load_queue,
> };
>
> +static int virtio_pci_uninit(PCIDevice *pci_dev)
> +{
> + VirtIOPCIProxy *proxy = container_of(pci_dev, VirtIOPCIProxy, pci_dev);
> + VirtIODevice *vdev = proxy->vdev;
> +
> + if (vdev->uninit) {
> + vdev->uninit(vdev);
> + }
> +
> + if (vdev->nvectors) {
> + return msix_uninit(pci_dev);
> + }
> +
> + return 0;
> +}
> +
> static void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice *vdev,
> uint16_t vendor, uint16_t device,
> uint16_t class_code, uint8_t pif)
> @@ -407,10 +423,11 @@ static void virtio_init_pci(VirtIOPCIProxy *proxy,
> VirtIODevice *vdev,
> PCI_ADDRESS_SPACE_MEM,
> msix_mmio_map);
> proxy->pci_dev.config_write = virtio_write_config;
> - proxy->pci_dev.unregister = msix_uninit;
> } else
> vdev->nvectors = 0;
>
> + proxy->pci_dev.unregister = virtio_pci_uninit;
> +
> size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev) + vdev->config_len;
> if (size & (size-1))
> size = 1 << qemu_fls(size);
> diff --git a/hw/virtio.h b/hw/virtio.h
> index aa55677..330b317 100644
> --- a/hw/virtio.h
> +++ b/hw/virtio.h
> @@ -103,6 +103,7 @@ struct VirtIODevice
> void (*get_config)(VirtIODevice *vdev, uint8_t *config);
> void (*set_config)(VirtIODevice *vdev, const uint8_t *config);
> void (*reset)(VirtIODevice *vdev);
> + void (*uninit)(VirtIODevice *vdev);
> VirtQueue *vq;
> const VirtIOBindings *binding;
> void *binding_opaque;
> diff --git a/sysemu.h b/sysemu.h
> index ce25109..18f610b 100644
> --- a/sysemu.h
> +++ b/sysemu.h
> @@ -193,6 +193,8 @@ extern const char *drive_get_serial(BlockDriverState
> *bdrv);
> extern BlockInterfaceErrorAction drive_get_onerror(BlockDriverState *bdrv);
>
> BlockDriverState *qdev_init_bdrv(DeviceState *dev, BlockInterfaceType type);
> +void qdev_uninit_bdrv(BlockDriverState *bs, BlockInterfaceType type);
> +
>
> struct drive_opt {
> const char *file;
Hi Anthony-
Thanks for the patch. I've tested this against qemu-kvm-0.11.0 and it's
working well. I can add/remove/add/remove virtio disks without
segfaulting qemu. We're going to carry this patch in Ubuntu.
Tested-by: Dustin Kirkland <address@hidden>
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