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Subject[PATCH v9 10/13] nvme-pci: Add support for P2P memory in requests
For P2P requests, we must use the pci_p2pmem_map_sg() function
instead of the dma_map_sg functions.

With that, we can then indicate PCI_P2P support in the request queue.
For this, we create an NVME_F_PCI_P2P flag which tells the core to
set QUEUE_FLAG_PCI_P2P in the request queue.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
---
drivers/nvme/host/core.c | 4 ++++
drivers/nvme/host/nvme.h | 1 +
drivers/nvme/host/pci.c | 17 +++++++++++++----
3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index dd8ec1dd9219..6033ce2fd3e9 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3051,7 +3051,11 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
ns->queue = blk_mq_init_queue(ctrl->tagset);
if (IS_ERR(ns->queue))
goto out_free_ns;
+
blk_queue_flag_set(QUEUE_FLAG_NONROT, ns->queue);
+ if (ctrl->ops->flags & NVME_F_PCI_P2PDMA)
+ blk_queue_flag_set(QUEUE_FLAG_PCI_P2PDMA, ns->queue);
+
ns->queue->queuedata = ns;
ns->ctrl = ctrl;

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index bb4a2003c097..4030743c90aa 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -343,6 +343,7 @@ struct nvme_ctrl_ops {
unsigned int flags;
#define NVME_F_FABRICS (1 << 0)
#define NVME_F_METADATA_SUPPORTED (1 << 1)
+#define NVME_F_PCI_P2PDMA (1 << 2)
int (*reg_read32)(struct nvme_ctrl *ctrl, u32 off, u32 *val);
int (*reg_write32)(struct nvme_ctrl *ctrl, u32 off, u32 val);
int (*reg_read64)(struct nvme_ctrl *ctrl, u32 off, u64 *val);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index f434706a04e8..0d6c41bc2b35 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -745,8 +745,13 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
goto out;

ret = BLK_STS_RESOURCE;
- nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,
- DMA_ATTR_NO_WARN);
+
+ if (is_pci_p2pdma_page(sg_page(iod->sg)))
+ nr_mapped = pci_p2pdma_map_sg(dev->dev, iod->sg, iod->nents,
+ dma_dir);
+ else
+ nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents,
+ dma_dir, DMA_ATTR_NO_WARN);
if (!nr_mapped)
goto out;

@@ -788,7 +793,10 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
DMA_TO_DEVICE : DMA_FROM_DEVICE;

if (iod->nents) {
- dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
+ /* P2PDMA requests do not need to be unmapped */
+ if (!is_pci_p2pdma_page(sg_page(iod->sg)))
+ dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
+
if (blk_integrity_rq(req))
dma_unmap_sg(dev->dev, &iod->meta_sg, 1, dma_dir);
}
@@ -2400,7 +2408,8 @@ static int nvme_pci_get_address(struct nvme_ctrl *ctrl, char *buf, int size)
static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
.name = "pcie",
.module = THIS_MODULE,
- .flags = NVME_F_METADATA_SUPPORTED,
+ .flags = NVME_F_METADATA_SUPPORTED |
+ NVME_F_PCI_P2PDMA,
.reg_read32 = nvme_pci_reg_read32,
.reg_write32 = nvme_pci_reg_write32,
.reg_read64 = nvme_pci_reg_read64,
--
2.19.0
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