From 7d3b214ae45be7fafaf514c089360a3efc6bc23f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Fri, 21 Aug 2020 21:53:52 +0200 Subject: [PATCH] block/nvme: Use union of NvmeIdCtrl / NvmeIdNs structures MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We allocate an unique chunk of memory then use it for two different structures. By using an union, we make it clear the data is overlapping (and we can remove the casts). Suggested-by: Stefan Hajnoczi Reviewed-by: Stefan Hajnoczi Reviewed-by: Stefano Garzarella Signed-off-by: Philippe Mathieu-Daudé Message-Id: <20200821195359.1285345-9-philmd@redhat.com> Signed-off-by: Kevin Wolf --- block/nvme.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/block/nvme.c b/block/nvme.c index 0992f2fb57..b0d55ecfb2 100644 --- a/block/nvme.c +++ b/block/nvme.c @@ -508,9 +508,10 @@ static int nvme_cmd_sync(BlockDriverState *bs, NVMeQueuePair *q, static void nvme_identify(BlockDriverState *bs, int namespace, Error **errp) { BDRVNVMeState *s = bs->opaque; - NvmeIdCtrl *idctrl; - NvmeIdNs *idns; - uint8_t *id; + union { + NvmeIdCtrl ctrl; + NvmeIdNs ns; + } *id; NvmeLBAF *lbaf; uint16_t oncs; int r; @@ -520,14 +521,12 @@ static void nvme_identify(BlockDriverState *bs, int namespace, Error **errp) .cdw10 = cpu_to_le32(0x1), }; - id = qemu_try_blockalign0(bs, sizeof(NvmeIdCtrl)); + id = qemu_try_blockalign0(bs, sizeof(*id)); if (!id) { error_setg(errp, "Cannot allocate buffer for identify response"); goto out; } - idctrl = (NvmeIdCtrl *)id; - idns = (NvmeIdNs *)id; - r = qemu_vfio_dma_map(s->vfio, id, sizeof(NvmeIdCtrl), true, &iova); + r = qemu_vfio_dma_map(s->vfio, id, sizeof(*id), true, &iova); if (r) { error_setg(errp, "Cannot map buffer for DMA"); goto out; @@ -539,22 +538,22 @@ static void nvme_identify(BlockDriverState *bs, int namespace, Error **errp) goto out; } - if (le32_to_cpu(idctrl->nn) < namespace) { + if (le32_to_cpu(id->ctrl.nn) < namespace) { error_setg(errp, "Invalid namespace"); goto out; } - s->write_cache_supported = le32_to_cpu(idctrl->vwc) & 0x1; - s->max_transfer = (idctrl->mdts ? 1 << idctrl->mdts : 0) * s->page_size; + s->write_cache_supported = le32_to_cpu(id->ctrl.vwc) & 0x1; + s->max_transfer = (id->ctrl.mdts ? 1 << id->ctrl.mdts : 0) * s->page_size; /* For now the page list buffer per command is one page, to hold at most * s->page_size / sizeof(uint64_t) entries. */ s->max_transfer = MIN_NON_ZERO(s->max_transfer, s->page_size / sizeof(uint64_t) * s->page_size); - oncs = le16_to_cpu(idctrl->oncs); + oncs = le16_to_cpu(id->ctrl.oncs); s->supports_write_zeroes = !!(oncs & NVME_ONCS_WRITE_ZEROES); s->supports_discard = !!(oncs & NVME_ONCS_DSM); - memset(id, 0, 4096); + memset(id, 0, sizeof(*id)); cmd.cdw10 = 0; cmd.nsid = cpu_to_le32(namespace); if (nvme_cmd_sync(bs, s->queues[INDEX_ADMIN], &cmd)) { @@ -562,11 +561,11 @@ static void nvme_identify(BlockDriverState *bs, int namespace, Error **errp) goto out; } - s->nsze = le64_to_cpu(idns->nsze); - lbaf = &idns->lbaf[NVME_ID_NS_FLBAS_INDEX(idns->flbas)]; + s->nsze = le64_to_cpu(id->ns.nsze); + lbaf = &id->ns.lbaf[NVME_ID_NS_FLBAS_INDEX(id->ns.flbas)]; - if (NVME_ID_NS_DLFEAT_WRITE_ZEROES(idns->dlfeat) && - NVME_ID_NS_DLFEAT_READ_BEHAVIOR(idns->dlfeat) == + if (NVME_ID_NS_DLFEAT_WRITE_ZEROES(id->ns.dlfeat) && + NVME_ID_NS_DLFEAT_READ_BEHAVIOR(id->ns.dlfeat) == NVME_ID_NS_DLFEAT_READ_BEHAVIOR_ZEROES) { bs->supported_write_flags |= BDRV_REQ_MAY_UNMAP; }