From 354d162ba527c6d935b59c53c644722d533607cd Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Mon, 6 Nov 2023 18:12:30 +0100 Subject: [PATCH] swiotlb-xen: provide the "max_mapping_size" method MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit bff2a2d453a1b683378b4508b86b84389f551a00 upstream. There's a bug that when using the XEN hypervisor with bios with large multi-page bio vectors on NVMe, the kernel deadlocks [1]. The deadlocks are caused by inability to map a large bio vector - dma_map_sgtable always returns an error, this gets propagated to the block layer as BLK_STS_RESOURCE and the block layer retries the request indefinitely. XEN uses the swiotlb framework to map discontiguous pages into contiguous runs that are submitted to the PCIe device. The swiotlb framework has a limitation on the length of a mapping - this needs to be announced with the max_mapping_size method to make sure that the hardware drivers do not create larger mappings. Without max_mapping_size, the NVMe block driver would create large mappings that overrun the maximum mapping size. Reported-by: Marek Marczykowski-Górecki Link: https://lore.kernel.org/stable/ZTNH0qtmint%2FzLJZ@mail-itl/ [1] Tested-by: Marek Marczykowski-Górecki Suggested-by: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: Keith Busch Signed-off-by: Mikulas Patocka Acked-by: Stefano Stabellini Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/151bef41-e817-aea9-675-a35fdac4ed@redhat.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman --- drivers/xen/swiotlb-xen.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index 67aa74d..7290f2b 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -405,4 +405,5 @@ const struct dma_map_ops xen_swiotlb_dma_ops = { .get_sgtable = dma_common_get_sgtable, .alloc_pages = dma_common_alloc_pages, .free_pages = dma_common_free_pages, + .max_mapping_size = swiotlb_max_mapping_size, }; -- 2.7.4