[PATCH AUTOSEL 5.2 136/171] nvme-pci: limit max_hw_sectors based on the DMA max mapping size

[Sasha Levin]

From: Christoph Hellwig <hch@xxxxxx>

[ Upstream commit 7637de311bd2124b298a072852448b940d8a34b9 ]

When running a NVMe device that is attached to a addressing
challenged PCIe root port that requires bounce buffering, our
request sizes can easily overflow the swiotlb bounce buffer
size.  Limit the maximum I/O size to the limit exposed by
the DMA mapping subsystem.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reported-by: Atish Patra <Atish.Patra@xxxxxxx>
Tested-by: Atish Patra <Atish.Patra@xxxxxxx>
Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/nvme/host/pci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 5dfa067f6506..5c45f4cab060 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2515,7 +2515,8 @@ static void nvme_reset_work(struct work_struct *work)
 	 * Limit the max command size to prevent iod->sg allocations going
 	 * over a single page.
 	 */
-	dev->ctrl.max_hw_sectors = NVME_MAX_KB_SZ << 1;
+	dev->ctrl.max_hw_sectors = min_t(u32,
+		NVME_MAX_KB_SZ << 1, dma_max_mapping_size(dev->dev) >> 9);
 	dev->ctrl.max_segments = NVME_MAX_SEGS;
 
 	/*
-- 
2.20.1