From 42824b4d16da56a50ff4027f6cd22378e0e2666e Mon Sep 17 00:00:00 2001 From: Changpeng Liu Date: Wed, 13 Feb 2019 09:48:57 +0800 Subject: [PATCH] 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: Changpeng Liu Reviewed-by: Michael S. Tsirkin 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: Stefan Hajnoczi --- hw/block/virtio-blk.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 843bb2bec8ea..cf7f47eaba8c 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -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;