Commit 4ada797b authored by Juergen Gross's avatar Juergen Gross Committed by Stefano Stabellini
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xen: use native disk xenbus protocol if possible 



The qdisk implementation is using the native xenbus protocol only in
case of no protocol specified at all. As using the explicit 32- or
64-bit protocol is slower than the native one due to copying requests
not by memcpy but element for element, this is not optimal.

Correct this by using the native protocol in case word sizes of
frontend and backend match.

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarAnthony PERARD <anthony.perard@citrix.com>
Signed-off-by: default avatarStefano Stabellini <sstabellini@kernel.org>
parent 12d2c418

hw/block/xen_disk.c

+10 −8
Original line number Diff line number Diff line
@@ -976,14 +976,16 @@ static int blk_connect(struct XenDevice *xendev) 
        blkdev->feature_persistent = !!pers;

    }



    if (!blkdev->xendev.protocol) {

        blkdev->protocol = BLKIF_PROTOCOL_NATIVE;

    if (blkdev->xendev.protocol) {

        if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) == 0) {

    } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_NATIVE) == 0) {

        blkdev->protocol = BLKIF_PROTOCOL_NATIVE;

    } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) == 0) {

        blkdev->protocol = BLKIF_PROTOCOL_X86_32;

        }

        if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) == 0) {

    } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) == 0) {

        blkdev->protocol = BLKIF_PROTOCOL_X86_64;

        }

    } else {

        blkdev->protocol = BLKIF_PROTOCOL_NATIVE;

    }



    blkdev->sring = xengnttab_map_grant_ref(blkdev->xendev.gnttabdev,