From a17975b5fe0cb2b17fdf0335430d5f4d2ab3ba4d Mon Sep 17 00:00:00 2001
From: Matt DeVillier matt.devillier@gmail.com Date: Sun, 12 Aug 2018 15:26:59 -0500 Subject: [PATCH 1/1] nvme: fix I/O queue length calculation overflow
Commit cd47172 changed the I/O queue length calculation to use the Maximum Queue Entries Supported (MQES) value from the capabilities register, plus one, with a maximum value of NVME_PAGE_SIZE.
An unintended effect from this is that a MQES value of 0xFFFF yields a length of zero, resulting in the queue allocation failing. Fix this by checking for a zero length when checking that the length exceeds NVME_PAGE_SIZE, and setting to NVME_PAGE_SIZE.
TEST: build/boot on a Purism Librem13v2 with a MyDigitalSSD BPX NVMe drive, which reports a MQES of 0xFFFF. Verify NVMe drive present in boot menu and OS boots successfully.
Signed-off-by: Matt DeVillier matt.devillier@gmail.com --- src/hw/nvme.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/hw/nvme.c b/src/hw/nvme.c index e6d739d..c2d6863 100644 --- a/src/hw/nvme.c +++ b/src/hw/nvme.c @@ -319,7 +319,7 @@ nvme_create_io_cq(struct nvme_ctrl *ctrl, struct nvme_cq *cq, u16 q_idx) int rc; struct nvme_sqe *cmd_create_cq; u16 length = 1 + (ctrl->reg->cap & 0xffff); - if (length > NVME_PAGE_SIZE / sizeof(struct nvme_cqe)) + if (length == 0 || length > NVME_PAGE_SIZE / sizeof(struct nvme_cqe)) length = NVME_PAGE_SIZE / sizeof(struct nvme_cqe);
rc = nvme_init_cq(ctrl, cq, q_idx, length); @@ -363,7 +363,7 @@ nvme_create_io_sq(struct nvme_ctrl *ctrl, struct nvme_sq *sq, u16 q_idx, struct int rc; struct nvme_sqe *cmd_create_sq; u16 length = 1 + (ctrl->reg->cap & 0xffff); - if (length > NVME_PAGE_SIZE / sizeof(struct nvme_cqe)) + if (length == 0 || length > NVME_PAGE_SIZE / sizeof(struct nvme_cqe)) length = NVME_PAGE_SIZE / sizeof(struct nvme_cqe);
rc = nvme_init_sq(ctrl, sq, q_idx, length, cq);