From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51429) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dExuQ-0007gj-Vf for qemu-devel@nongnu.org; Sun, 28 May 2017 09:07:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dExuN-0004G4-QM for qemu-devel@nongnu.org; Sun, 28 May 2017 09:07:02 -0400 Received: from mail-wm0-x233.google.com ([2a00:1450:400c:c09::233]:38856) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1dExuN-0004Fw-HC for qemu-devel@nongnu.org; Sun, 28 May 2017 09:06:59 -0400 Received: by mail-wm0-x233.google.com with SMTP id e127so28036989wmg.1 for ; Sun, 28 May 2017 06:06:59 -0700 (PDT) From: Dan Aloni Date: Sun, 28 May 2017 16:06:49 +0300 Message-Id: <20170528130649.28168-1-dan@kernelim.com> Subject: [Qemu-devel] [PATCH] nvme: Fix get/set number of queues feature, again List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Alex Friedman , Keith Busch , Stefan Hajnoczi The number of queues that should be return by the admin command should: 1) Only mention the number of non-admin queues. 2) It is zero-based, meaning that '0 == one non-admin queue', '1 == two non-admin queues', and so forth. Because our `num_queues` means the number of queues _plus_ the admin queue, then the right calculation for the number returned from the admin command is `num_queues - 2`, combining the two requirements mentioned. The issue was discovered by reducing num_queues from 64 to 8 and running a Linux VM with an SMP parameter larger than that (e.g. 22). It tries to utilize all queues, and therefore fails with an invalid queue number when trying to queue I/Os on the last queue. Signed-off-by: Dan Aloni CC: Alex Friedman CC: Keith Busch CC: Stefan Hajnoczi --- hw/block/nvme.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hw/block/nvme.c b/hw/block/nvme.c index 7428db9f0c91..08ddf3a39e2f 100644 --- a/hw/block/nvme.c +++ b/hw/block/nvme.c @@ -573,7 +573,7 @@ static uint16_t nvme_get_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req) result = blk_enable_write_cache(n->conf.blk); break; case NVME_NUMBER_OF_QUEUES: - result = cpu_to_le32((n->num_queues - 1) | ((n->num_queues - 1) << 16)); + result = cpu_to_le32((n->num_queues - 2) | ((n->num_queues - 2) << 16)); break; default: return NVME_INVALID_FIELD | NVME_DNR; @@ -594,7 +594,7 @@ static uint16_t nvme_set_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req) break; case NVME_NUMBER_OF_QUEUES: req->cqe.result = - cpu_to_le32((n->num_queues - 1) | ((n->num_queues - 1) << 16)); + cpu_to_le32((n->num_queues - 2) | ((n->num_queues - 2) << 16)); break; default: return NVME_INVALID_FIELD | NVME_DNR; -- 2.9.4