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cxl/region：Fix overflow issue in alloc_hpa()

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Creating a region with 16 memory devices caused a problem. The div_u64_rem
function, used for dividing an unsigned 64-bit number by a 32-bit one,
faced an issue when SZ_256M * p->interleave_ways. The result surpassed
the maximum limit of the 32-bit divisor (4G), leading to an overflow
and a remainder of 0.
note: At this point, p->interleave_ways is 16, meaning 16 * 256M = 4G

To fix this issue, I replaced the div_u64_rem function with div64_u64_rem
and adjusted the type of the remainder.

Signed-off-by: Quanquan Cao <caoqq@fujitsu.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Fixes: 23a22cd1c9 ("cxl/region: Allocate HPA capacity to regions")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Quanquan Cao 2024-01-24 17:15:26 +08:00 committed by Dan Williams
parent d72a4caf68
commit d76779dd36
1 changed files with 2 additions and 2 deletions
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4
drivers/cxl/core/region.c
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@ -525,7 +525,7 @@ static int alloc_hpa(struct cxl_region *cxlr, resource_size_t size)
struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
struct cxl_region_params *p = &cxlr->params;
struct resource *res;
u32 remainder = 0;
u64 remainder = 0;
lockdep_assert_held_write(&cxl_region_rwsem);
@ -545,7 +545,7 @@ static int alloc_hpa(struct cxl_region *cxlr, resource_size_t size)
(cxlr->mode == CXL_DECODER_PMEM && uuid_is_null(&p->uuid)))
return -ENXIO;
div_u64_rem(size, SZ_256M * p->interleave_ways, &remainder);
div64_u64_rem(size, (u64)SZ_256M * p->interleave_ways, &remainder);
if (remainder)
return -EINVAL;