From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49189) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fD80j-0005X3-KO for qemu-devel@nongnu.org; Mon, 30 Apr 2018 08:34:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fD80h-0000vp-UR for qemu-devel@nongnu.org; Mon, 30 Apr 2018 08:34:29 -0400 From: Paul Durrant Date: Mon, 30 Apr 2018 13:01:37 +0100 Message-ID: <1525089699-13411-3-git-send-email-paul.durrant@citrix.com> In-Reply-To: <1525089699-13411-1-git-send-email-paul.durrant@citrix.com> References: <1525089699-13411-1-git-send-email-paul.durrant@citrix.com> MIME-Version: 1.0 Content-Type: text/plain Subject: [Qemu-devel] [PATCH 2/4] block/xen_disk: remove use of grant map/unmap List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xen-devel@lists.xenproject.org, qemu-block@nongnu.org, qemu-devel@nongnu.org Cc: Paul Durrant , Stefano Stabellini , Anthony Perard , Kevin Wolf , Max Reitz The grant copy operation was added to libxengnttab in Xen 4.8.0. If grant copy is available then data from the guest will be copied rather than mapped. The xen_disk source can be significantly simplified by removing this now redundant code. Signed-off-by: Paul Durrant --- Cc: Stefano Stabellini Cc: Anthony Perard Cc: Kevin Wolf Cc: Max Reitz --- hw/block/xen_disk.c | 194 ++++++++-------------------------------------------- 1 file changed, 27 insertions(+), 167 deletions(-) diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index b33611a..8f4e229 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -36,10 +36,6 @@ /* ------------------------------------------------------------- */ -static int batch_maps = 0; - -/* ------------------------------------------------------------- */ - #define BLOCK_SIZE 512 #define IOCB_COUNT (BLKIF_MAX_SEGMENTS_PER_REQUEST + 2) @@ -51,12 +47,9 @@ struct ioreq { off_t start; QEMUIOVector v; int presync; - uint8_t mapped; - /* grant mapping */ uint32_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST]; uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST]; - int prot; void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST]; void *pages; @@ -89,7 +82,6 @@ struct XenBlkDev { int protocol; blkif_back_rings_t rings; int more_work; - int cnt_map; /* request lists */ QLIST_HEAD(inflight_head, ioreq) inflight; @@ -119,11 +111,9 @@ static void ioreq_reset(struct ioreq *ioreq) ioreq->status = 0; ioreq->start = 0; ioreq->presync = 0; - ioreq->mapped = 0; memset(ioreq->domids, 0, sizeof(ioreq->domids)); memset(ioreq->refs, 0, sizeof(ioreq->refs)); - ioreq->prot = 0; memset(ioreq->page, 0, sizeof(ioreq->page)); ioreq->pages = NULL; @@ -204,7 +194,6 @@ static int ioreq_parse(struct ioreq *ioreq) ioreq->req.handle, ioreq->req.id, ioreq->req.sector_number); switch (ioreq->req.operation) { case BLKIF_OP_READ: - ioreq->prot = PROT_WRITE; /* to memory */ break; case BLKIF_OP_FLUSH_DISKCACHE: ioreq->presync = 1; @@ -213,7 +202,6 @@ static int ioreq_parse(struct ioreq *ioreq) } /* fall through */ case BLKIF_OP_WRITE: - ioreq->prot = PROT_READ; /* from memory */ break; case BLKIF_OP_DISCARD: return 0; @@ -261,88 +249,6 @@ err: return -1; } -static void ioreq_unmap(struct ioreq *ioreq) -{ - xengnttab_handle *gnt = ioreq->blkdev->xendev.gnttabdev; - int i; - - if (ioreq->v.niov == 0 || ioreq->mapped == 0) { - return; - } - if (batch_maps) { - if (!ioreq->pages) { - return; - } - if (xengnttab_unmap(gnt, ioreq->pages, ioreq->v.niov) != 0) { - xen_pv_printf(&ioreq->blkdev->xendev, 0, - "xengnttab_unmap failed: %s\n", - strerror(errno)); - } - ioreq->blkdev->cnt_map -= ioreq->v.niov; - ioreq->pages = NULL; - } else { - for (i = 0; i < ioreq->v.niov; i++) { - if (!ioreq->page[i]) { - continue; - } - if (xengnttab_unmap(gnt, ioreq->page[i], 1) != 0) { - xen_pv_printf(&ioreq->blkdev->xendev, 0, - "xengnttab_unmap failed: %s\n", - strerror(errno)); - } - ioreq->blkdev->cnt_map--; - ioreq->page[i] = NULL; - } - } - ioreq->mapped = 0; -} - -static int ioreq_map(struct ioreq *ioreq) -{ - xengnttab_handle *gnt = ioreq->blkdev->xendev.gnttabdev; - int i; - - if (ioreq->v.niov == 0 || ioreq->mapped == 1) { - return 0; - } - if (batch_maps) { - ioreq->pages = xengnttab_map_grant_refs - (gnt, ioreq->v.niov, ioreq->domids, ioreq->refs, ioreq->prot); - if (ioreq->pages == NULL) { - xen_pv_printf(&ioreq->blkdev->xendev, 0, - "can't map %d grant refs (%s, %d maps)\n", - ioreq->v.niov, strerror(errno), - ioreq->blkdev->cnt_map); - return -1; - } - for (i = 0; i < ioreq->v.niov; i++) { - ioreq->v.iov[i].iov_base = ioreq->pages + i * XC_PAGE_SIZE + - (uintptr_t)ioreq->v.iov[i].iov_base; - } - ioreq->blkdev->cnt_map += ioreq->v.niov; - } else { - for (i = 0; i < ioreq->v.niov; i++) { - ioreq->page[i] = xengnttab_map_grant_ref - (gnt, ioreq->domids[i], ioreq->refs[i], ioreq->prot); - if (ioreq->page[i] == NULL) { - xen_pv_printf(&ioreq->blkdev->xendev, 0, - "can't map grant ref %d (%s, %d maps)\n", - ioreq->refs[i], strerror(errno), - ioreq->blkdev->cnt_map); - ioreq->mapped = 1; - ioreq_unmap(ioreq); - return -1; - } - ioreq->v.iov[i].iov_base = ioreq->page[i] + - (uintptr_t)ioreq->v.iov[i].iov_base; - } - } - ioreq->mapped = 1; - return 0; -} - -#if CONFIG_XEN_CTRL_INTERFACE_VERSION >= 40800 - static void ioreq_free_copy_buffers(struct ioreq *ioreq) { int i; @@ -424,22 +330,6 @@ static int ioreq_grant_copy(struct ioreq *ioreq) return rc; } -#else -static void ioreq_free_copy_buffers(struct ioreq *ioreq) -{ - abort(); -} - -static int ioreq_init_copy_buffers(struct ioreq *ioreq) -{ - abort(); -} - -static int ioreq_grant_copy(struct ioreq *ioreq) -{ - abort(); -} -#endif static int ioreq_runio_qemu_aio(struct ioreq *ioreq); @@ -466,32 +356,28 @@ static void qemu_aio_complete(void *opaque, int ret) goto done; } - if (xen_feature_grant_copy) { - switch (ioreq->req.operation) { - case BLKIF_OP_READ: - /* in case of failure ioreq->aio_errors is increased */ - if (ret == 0) { - ioreq_grant_copy(ioreq); - } - ioreq_free_copy_buffers(ioreq); - break; - case BLKIF_OP_WRITE: - case BLKIF_OP_FLUSH_DISKCACHE: - if (!ioreq->req.nr_segments) { - break; - } - ioreq_free_copy_buffers(ioreq); - break; - default: + switch (ioreq->req.operation) { + case BLKIF_OP_READ: + /* in case of failure ioreq->aio_errors is increased */ + if (ret == 0) { + ioreq_grant_copy(ioreq); + } + ioreq_free_copy_buffers(ioreq); + break; + case BLKIF_OP_WRITE: + case BLKIF_OP_FLUSH_DISKCACHE: + if (!ioreq->req.nr_segments) { break; } + ioreq_free_copy_buffers(ioreq); + break; + default: + break; } ioreq->status = ioreq->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY; - if (!xen_feature_grant_copy) { - ioreq_unmap(ioreq); - } ioreq_finish(ioreq); + switch (ioreq->req.operation) { case BLKIF_OP_WRITE: case BLKIF_OP_FLUSH_DISKCACHE: @@ -551,18 +437,13 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq) { struct XenBlkDev *blkdev = ioreq->blkdev; - if (xen_feature_grant_copy) { - ioreq_init_copy_buffers(ioreq); - if (ioreq->req.nr_segments && (ioreq->req.operation == BLKIF_OP_WRITE || - ioreq->req.operation == BLKIF_OP_FLUSH_DISKCACHE) && - ioreq_grant_copy(ioreq)) { - ioreq_free_copy_buffers(ioreq); - goto err; - } - } else { - if (ioreq->req.nr_segments && ioreq_map(ioreq)) { - goto err; - } + ioreq_init_copy_buffers(ioreq); + if (ioreq->req.nr_segments && + (ioreq->req.operation == BLKIF_OP_WRITE || + ioreq->req.operation == BLKIF_OP_FLUSH_DISKCACHE) && + ioreq_grant_copy(ioreq)) { + ioreq_free_copy_buffers(ioreq); + goto err; } ioreq->aio_inflight++; @@ -603,9 +484,6 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq) } default: /* unknown operation (shouldn't happen -- parse catches this) */ - if (!xen_feature_grant_copy) { - ioreq_unmap(ioreq); - } goto err; } @@ -791,10 +669,6 @@ static void blk_alloc(struct XenDevice *xendev) blkdev->ctx = iothread_get_aio_context(blkdev->iothread); blkdev->bh = aio_bh_new(blkdev->ctx, blk_bh, blkdev); - - if (xen_mode != XEN_EMULATE) { - batch_maps = 1; - } } static void blk_parse_discard(struct XenBlkDev *blkdev) @@ -877,8 +751,9 @@ static int blk_init(struct XenDevice *xendev) blkdev->file_blk = BLOCK_SIZE; - xen_pv_printf(&blkdev->xendev, 3, "grant copy operation %s\n", - xen_feature_grant_copy ? "enabled" : "disabled"); + if (!xen_feature_grant_copy) { + goto out_error; + } /* fill info * blk_connect supplies sector-size and sectors @@ -910,15 +785,6 @@ out_error: return -1; } -/* - * We need to account for the grant allocations requiring contiguous - * chunks; the worst case number would be - * max_req * max_seg + (max_req - 1) * (max_seg - 1) + 1, - * but in order to keep things simple just use - * 2 * max_req * max_seg. - */ -#define MAX_GRANTS(max_req, max_seg) (2 * (max_req) * (max_seg)) - static int blk_connect(struct XenDevice *xendev) { struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev); @@ -1079,11 +945,8 @@ static int blk_connect(struct XenDevice *xendev) return -1; } - /* Calculate the maximum number of grants needed by ioreqs */ - max_grants = MAX_GRANTS(blkdev->max_requests, - BLKIF_MAX_SEGMENTS_PER_REQUEST); /* Add on the number needed for the ring pages */ - max_grants += blkdev->nr_ring_ref; + max_grants = blkdev->nr_ring_ref; blkdev->xendev.gnttabdev = xengnttab_open(NULL, 0); if (blkdev->xendev.gnttabdev == NULL) { @@ -1114,8 +977,6 @@ static int blk_connect(struct XenDevice *xendev) return -1; } - blkdev->cnt_map++; - switch (blkdev->protocol) { case BLKIF_PROTOCOL_NATIVE: { @@ -1171,7 +1032,6 @@ static void blk_disconnect(struct XenDevice *xendev) if (blkdev->sring) { xengnttab_unmap(blkdev->xendev.gnttabdev, blkdev->sring, blkdev->nr_ring_ref); - blkdev->cnt_map--; blkdev->sring = NULL; } -- 2.1.4