[core-for-CI] nvme-pci: don't use dma_alloc_noncontiguous with 0 merge boundary

[Luca Coelho]

Hi Chaitanya,

On Wed, 2024-12-04 at 11:36 +0530, Chaitanya Kumar Borah wrote:
> From: Christoph Hellwig <hch at lst.de>
> 
> Only call into nvme_alloc_host_mem_single which uses
> dma_alloc_noncontiguous when there is non-null dma merge boundary.
> Without this we'll call into dma_alloc_noncontiguous for device using
> dma-direct, which can work fine as long as the preferred size is below the
> MAX_ORDER of the page allocator, but blows up with a warning if it is
> too large.
> 
> Fixes: 63a5c7a4b4c4 ("nvme-pci: use dma_alloc_noncontigous if possible")
> Reported-by: Leon Romanovsky <leon at kernel.org>
> Reported-by: Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com>
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> References: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13227
> Link: https://lore.kernel.org/linux-nvme/39a67024-2926-4a20-8feb-77dd64ab7c39@kernel.dk/T/#mfef47937b20e33aa3cc63a3af930f8a9f9baf8c2
> ---
>  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 4c644bb7f069..778f124c2e21 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2172,6 +2172,7 @@ static int nvme_alloc_host_mem_multi(struct nvme_dev *dev, u64 preferred,
>  
>  static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
>  {
> +	unsigned long dma_merge_moundary = dma_get_merge_boundary(dev->dev);
>  	u64 min_chunk = min_t(u64, preferred, PAGE_SIZE * MAX_ORDER_NR_PAGES);
>  	u64 hmminds = max_t(u32, dev->ctrl.hmminds * 4096, PAGE_SIZE * 2);
>  	u64 chunk_size;
> @@ -2180,7 +2181,7 @@ static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
>  	 * If there is an IOMMU that can merge pages, try a virtually
>  	 * non-contiguous allocation for a single segment first.
>  	 */
> -	if (!(PAGE_SIZE & dma_get_merge_boundary(dev->dev))) {
> +	if (dma_merge_moundary && (PAGE_SIZE & dma_merge_moundary) == 0) {
>  		if (!nvme_alloc_host_mem_single(dev, preferred))
>  			return 0;
>  	}

This looks sane and has already been reviewed in the linux-nvme mailing
list.  So, FWIW, you have my:

Acked-by: Luca Coelho <luciano.coelho at intel.com>

--
Cheers,
Luca.