From be8af3b6c80dc32cc690dbe1fcfe5efbb7a98ed7 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=UTF-8 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 2b385c1b4a99..ad3ee4857e15 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -579,4 +579,5 @@ 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, };