Commit 42824b4d authored by Changpeng Liu's avatar Changpeng Liu Committed by Stefan Hajnoczi
Browse files

virtio-blk: set correct config size for the host driver 



Commit caa1ee43 "vhost-user-blk: add discard/write zeroes features
support" added fields to struct virtio_blk_config. This changes
the size of the config space and breaks migration from QEMU 3.1
and older:

qemu-system-ppc64: get_pci_config_device: Bad config data: i=0x10 read: 41 device: 1 cmask: ff wmask: 80 w1cmask:0
qemu-system-ppc64: Failed to load PCIDevice:config
qemu-system-ppc64: Failed to load virtio-blk:virtio
qemu-system-ppc64: error while loading state for instance 0x0 of device 'pci@800000020000000:01.0/virtio-blk'
qemu-system-ppc64: load of migration failed: Invalid argument

Since virtio-blk doesn't support the "discard" and "write zeroes"
features, it shouldn't even expose the associated fields in the
config space actually. Just include all fields up to num_queues to
match QEMU 3.1 and older.

Signed-off-by: default avatarChangpeng Liu <changpeng.liu@intel.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Message-id: 1550022537-27565-1-git-send-email-changpeng.liu@intel.com
Message-Id: <1550022537-27565-1-git-send-email-changpeng.liu@intel.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 0b5e750b

hw/block/virtio-blk.c

+9 −4
Original line number Diff line number Diff line
@@ -28,6 +28,10 @@ 
#include "hw/virtio/virtio-bus.h"

#include "hw/virtio/virtio-access.h"



/* We don't support discard yet, hide associated config fields. */

#define VIRTIO_BLK_CFG_SIZE offsetof(struct virtio_blk_config, \

                                     max_discard_sectors)



static void virtio_blk_init_request(VirtIOBlock *s, VirtQueue *vq,

                                    VirtIOBlockReq *req)

{
@@ -757,7 +761,8 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) 
    blkcfg.alignment_offset = 0;

    blkcfg.wce = blk_enable_write_cache(s->blk);

    virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues);

    memcpy(config, &blkcfg, sizeof(struct virtio_blk_config));

    memcpy(config, &blkcfg, VIRTIO_BLK_CFG_SIZE);

    QEMU_BUILD_BUG_ON(VIRTIO_BLK_CFG_SIZE > sizeof(blkcfg));

}



static void virtio_blk_set_config(VirtIODevice *vdev, const uint8_t *config)
@@ -765,7 +770,8 @@ static void virtio_blk_set_config(VirtIODevice *vdev, const uint8_t *config) 
    VirtIOBlock *s = VIRTIO_BLK(vdev);

    struct virtio_blk_config blkcfg;



    memcpy(&blkcfg, config, sizeof(blkcfg));

    memcpy(&blkcfg, config, VIRTIO_BLK_CFG_SIZE);

    QEMU_BUILD_BUG_ON(VIRTIO_BLK_CFG_SIZE > sizeof(blkcfg));



    aio_context_acquire(blk_get_aio_context(s->blk));

    blk_set_enable_write_cache(s->blk, blkcfg.wce != 0);
@@ -948,8 +954,7 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp) 
        return;

    }



    virtio_init(vdev, "virtio-blk", VIRTIO_ID_BLOCK,

                sizeof(struct virtio_blk_config));

    virtio_init(vdev, "virtio-blk", VIRTIO_ID_BLOCK, VIRTIO_BLK_CFG_SIZE);



    s->blk = conf->conf.blk;

    s->rq = NULL;