From 2bcd05cf24a7de34e7e265247c010977e43f40bc Mon Sep 17 00:00:00 2001 From: Paul Durrant Date: Mon, 1 Apr 2019 13:17:19 +0100 Subject: xen-block: scale sector based quantities correctly The Xen blkif protocol requires that sector based quantities should be interpreted strictly as multiples of 512 bytes. Specifically: "first_sect and last_sect in blkif_request_segment, as well as sector_number in blkif_request, are always expressed in 512-byte units." Commit fcab2b464e06 "xen: add header and build dataplane/xen-block.c" incorrectly modified behaviour to use the block device logical_block_size property as the scale, instead of correctly shifting values by the hardcoded BDRV_SECTOR_BITS (and hence scaling them to 512 byte units). This patch undoes that change and restores compliance with the spec. Furthermore, this patch also restores the original xen_disk behaviour of advertizing a hardcoded 'sector-size' value of 512 in xenstore and scaling 'sectors' accordingly. The realize() method is also modified to fail if logical_block_size is set to anything other than 512. Signed-off-by: Paul Durrant Reviewed-by: Anthony PERARD Message-Id: <20190401121719.27208-1-paul.durrant@citrix.com> Signed-off-by: Anthony PERARD --- hw/block/xen-block.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'hw/block/xen-block.c') diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c index 475a67845d..ef635be4c2 100644 --- a/hw/block/xen-block.c +++ b/hw/block/xen-block.c @@ -149,7 +149,7 @@ static void xen_block_set_size(XenBlockDevice *blockdev) const char *type = object_get_typename(OBJECT(blockdev)); XenBlockVdev *vdev = &blockdev->props.vdev; BlockConf *conf = &blockdev->props.conf; - int64_t sectors = blk_getlength(conf->blk) / conf->logical_block_size; + int64_t sectors = blk_getlength(conf->blk) / XEN_BLKIF_SECTOR_SIZE; XenDevice *xendev = XEN_DEVICE(blockdev); trace_xen_block_size(type, vdev->disk, vdev->partition, sectors); @@ -223,6 +223,12 @@ static void xen_block_realize(XenDevice *xendev, Error **errp) blkconf_blocksizes(conf); + if (conf->logical_block_size != XEN_BLKIF_SECTOR_SIZE) { + error_setg(errp, "logical_block_size != %u not supported", + XEN_BLKIF_SECTOR_SIZE); + return; + } + if (conf->logical_block_size > conf->physical_block_size) { error_setg( errp, "logical_block_size > physical_block_size not supported"); @@ -253,7 +259,7 @@ static void xen_block_realize(XenDevice *xendev, Error **errp) blockdev->device_type); xen_device_backend_printf(xendev, "sector-size", "%u", - conf->logical_block_size); + XEN_BLKIF_SECTOR_SIZE); xen_block_set_size(blockdev); -- cgit 1.4.1