[PATCH 5.8 062/148] swiotlb-xen: use vmalloc_to_page on vmalloc virt addresses

Greg Kroah-Hartman
2020-08-24T08:34:36Z

From: Boris Ostrovsky <boris.ostrovsky@oracle.com>

[ Upstream commit 8b1e868f66076490189a36d984fcce286cdd6295 ]

xen_alloc_coherent_pages might return pages for which virt_to_phys and
virt_to_page don't work, e.g. ioremap'ed pages.

So in xen_swiotlb_free_coherent we can't assume that virt_to_page works.
Instead add a is_vmalloc_addr check and use vmalloc_to_page on vmalloc
virt addresses.

This patch fixes the following crash at boot on RPi4 (the underlying
issue is not RPi4 specific):
https://marc.info/?l=xen-devel&m=158862573216800

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Corey Minyard <cminyard@mvista.com>
Tested-by: Roman Shaposhnik <roman@zededa.com>
Link: https://lore.kernel.org/r/20200710223427.6897-1-sstabellini@kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/xen/swiotlb-xen.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index b6d27762c6f8c..5fbadd07819bd 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -335,6 +335,7 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
int order = get_order(size);
phys_addr_t phys;
u64 dma_mask = DMA_BIT_MASK(32);
+ struct page *page;

if (hwdev && hwdev->coherent_dma_mask)
dma_mask = hwdev->coherent_dma_mask;
@@ -346,9 +347,14 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
/* Convert the size to actually allocated. */
size = 1UL << (order + XEN_PAGE_SHIFT);

+ if (is_vmalloc_addr(vaddr))
+ page = vmalloc_to_page(vaddr);
+ else
+ page = virt_to_page(vaddr);
+
if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
range_straddles_page_boundary(phys, size)) &&
- TestClearPageXenRemapped(virt_to_page(vaddr)))
+ TestClearPageXenRemapped(page))
xen_destroy_contiguous_region(phys, order);

xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
--
2.25.1