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| author | Jan Beulich <jbeulich@suse.com> | 2021-09-07 14:05:12 +0200 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2021-09-15 08:42:04 +0200 |
| commit | d9a688add3d412c840e31060847a6a297b552316 (patch) | |
| tree | 0445d0c092a50df2c01cc221e505aa1eb9515ca5 /drivers/xen/swiotlb-xen.c | |
| parent | 4c092c59015f7adf0f07685f869edb96d997a756 (diff) | |
| download | linux-d9a688add3d412c840e31060847a6a297b552316.tar.bz2 | |
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/swiotlb-xen.c')
| -rw-r--r-- | drivers/xen/swiotlb-xen.c | 19 |
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; |