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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: Juergen Gross <jgross@suse.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
This commit is contained in:
Juergen Gross 2016-06-29 17:50:48 +02:00 committed by Stefano Stabellini
parent 12d2c4184c
commit 4ada797b05
1 changed files with 10 additions and 8 deletions
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18
hw/block/xen_disk.c
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@ -976,14 +976,16 @@ static int blk_connect(struct XenDevice *xendev)
blkdev->feature_persistent = !!pers;
}
blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
if (blkdev->xendev.protocol) {
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) {
blkdev->protocol = BLKIF_PROTOCOL_X86_64;
}
if (!blkdev->xendev.protocol) {
blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
} 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;
} 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,