From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49905) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dPybP-0008E2-Lr for qemu-devel@nongnu.org; Tue, 27 Jun 2017 18:04:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dPybL-0000NG-NC for qemu-devel@nongnu.org; Tue, 27 Jun 2017 18:04:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:40124) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dPybL-0000Mp-Gq for qemu-devel@nongnu.org; Tue, 27 Jun 2017 18:04:51 -0400 From: Stefano Stabellini Date: Tue, 27 Jun 2017 15:04:42 -0700 Message-Id: <1498601083-11799-2-git-send-email-sstabellini@kernel.org> In-Reply-To: <1498601083-11799-1-git-send-email-sstabellini@kernel.org> References: <1498601083-11799-1-git-send-email-sstabellini@kernel.org> Subject: [Qemu-devel] [PULL 2/3] xen-disk: only advertize feature-persistent if grant copy is not available List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: peter.maydell@linaro.org, stefanha@gmail.com Cc: sstabellini@kernel.org, stefanha@redhat.com, anthony.perard@citrix.com, xen-devel@lists.xenproject.org, qemu-devel@nongnu.org, Paul Durrant From: Paul Durrant If grant copy is available then it will always be used in preference to persistent maps. In this case feature-persistent should not be advertized to the frontend, otherwise it may needlessly copy data into persistently granted buffers. Signed-off-by: Paul Durrant Signed-off-by: Stefano Stabellini Reviewed-by: Stefano Stabellini --- hw/block/xen_disk.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index 9200511..8218741 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -1022,11 +1022,18 @@ static int blk_init(struct XenDevice *xendev) blkdev->file_blk = BLOCK_SIZE; + blkdev->feature_grant_copy = + (xengnttab_grant_copy(blkdev->xendev.gnttabdev, 0, NULL) == 0); + + xen_pv_printf(&blkdev->xendev, 3, "grant copy operation %s\n", + blkdev->feature_grant_copy ? "enabled" : "disabled"); + /* fill info * blk_connect supplies sector-size and sectors */ xenstore_write_be_int(&blkdev->xendev, "feature-flush-cache", 1); - xenstore_write_be_int(&blkdev->xendev, "feature-persistent", 1); + xenstore_write_be_int(&blkdev->xendev, "feature-persistent", + !blkdev->feature_grant_copy); xenstore_write_be_int(&blkdev->xendev, "info", info); blk_parse_discard(blkdev); @@ -1201,12 +1208,6 @@ static int blk_connect(struct XenDevice *xendev) xen_be_bind_evtchn(&blkdev->xendev); - blkdev->feature_grant_copy = - (xengnttab_grant_copy(blkdev->xendev.gnttabdev, 0, NULL) == 0); - - xen_pv_printf(&blkdev->xendev, 3, "grant copy operation %s\n", - blkdev->feature_grant_copy ? "enabled" : "disabled"); - xen_pv_printf(&blkdev->xendev, 1, "ok: proto %s, ring-ref %d, " "remote port %d, local port %d\n", blkdev->xendev.protocol, blkdev->ring_ref, -- 1.9.1