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authorJan Beulich <jbeulich@suse.com>2021-09-07 14:05:12 +0200
committerJuergen Gross <jgross@suse.com>2021-09-15 08:42:04 +0200
commitd9a688add3d412c840e31060847a6a297b552316 (patch)
tree0445d0c092a50df2c01cc221e505aa1eb9515ca5 /drivers/xen
parent4c092c59015f7adf0f07685f869edb96d997a756 (diff)
swiotlb-xen: maintain slab count properly
Generic swiotlb code makes sure to keep the slab count a multiple of the number of slabs per segment. Yet even without checking whether any such assumption is made elsewhere, it is easy to see that xen_swiotlb_fixup() might alter unrelated memory when calling xen_create_contiguous_region() for the last segment, when that's not a full one - the function acts on full order-N regions, not individual pages. Align the slab count suitably when halving it for a retry. Add a build time check and a runtime one. Replace the no longer useful local variable "slabs" by an "order" one calculated just once, outside of the loop. Re-use "order" for calculating "dma_bits", and change the type of the latter as well as the one of "i" while touching this anyway. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/dc054cb0-bec4-4db0-fc06-c9fc957b6e66@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/swiotlb-xen.c19
1 files changed, 9 insertions, 10 deletions
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index dbb18dc956f3..08fc694f05b7 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -106,27 +106,26 @@ static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr)
static int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
{
- int i, rc;
- int dma_bits;
+ int rc;
+ unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT);
+ unsigned int i, dma_bits = order + PAGE_SHIFT;
dma_addr_t dma_handle;
phys_addr_t p = virt_to_phys(buf);
- dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
+ BUILD_BUG_ON(IO_TLB_SEGSIZE & (IO_TLB_SEGSIZE - 1));
+ BUG_ON(nslabs % IO_TLB_SEGSIZE);
i = 0;
do {
- int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
-
do {
rc = xen_create_contiguous_region(
- p + (i << IO_TLB_SHIFT),
- get_order(slabs << IO_TLB_SHIFT),
+ p + (i << IO_TLB_SHIFT), order,
dma_bits, &dma_handle);
} while (rc && dma_bits++ < MAX_DMA_BITS);
if (rc)
return rc;
- i += slabs;
+ i += IO_TLB_SEGSIZE;
} while (i < nslabs);
return 0;
}
@@ -210,7 +209,7 @@ retry:
error:
if (repeat--) {
/* Min is 2MB */
- nslabs = max(1024UL, (nslabs >> 1));
+ nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE));
bytes = nslabs << IO_TLB_SHIFT;
pr_info("Lowering to %luMB\n", bytes >> 20);
goto retry;
@@ -245,7 +244,7 @@ retry:
memblock_free(__pa(start), PAGE_ALIGN(bytes));
if (repeat--) {
/* Min is 2MB */
- nslabs = max(1024UL, (nslabs >> 1));
+ nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE));
bytes = nslabs << IO_TLB_SHIFT;
pr_info("Lowering to %luMB\n", bytes >> 20);
goto retry;