Actually, it looks like something completely general isn't easily doable, not without some major dma API work. Here is what should fix nvme, but a few other drivers will need fixes as well:
--- >From 745541130409bc837a3416300f529b16eded8513 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig <[email protected]> Date: Wed, 5 Jun 2019 14:55:26 +0200 Subject: nvme-pci: don't limit DMA segement size NVMe uses PRPs (or optionally unlimited SGLs) for data transfers and has no specific limit for a single DMA segement. Limiting the size will cause problems because the block layer assumes PRP-ish devices using a virt boundary mask don't have a segment limit. And while this is true, we also really need to tell the DMA mapping layer about it, otherwise dma-debug will trip over it. Signed-off-by: Christoph Hellwig <[email protected]> Reported-by: Sebastian Ott <[email protected]> --- drivers/nvme/host/pci.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index f562154551ce..524d6bd6d095 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -2513,6 +2513,12 @@ static void nvme_reset_work(struct work_struct *work) */ dev->ctrl.max_hw_sectors = NVME_MAX_KB_SZ << 1; dev->ctrl.max_segments = NVME_MAX_SEGS; + + /* + * Don't limit the IOMMU merged segment size. + */ + dma_set_max_seg_size(dev->dev, 0xffffffff); + mutex_unlock(&dev->shutdown_lock); /* -- 2.20.1
