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intel_iommu: fix and simplify size calculation in process_device_iotlb_desc()

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We don't use 1ULL which is wrong during size calculation. Fix it, and
while at it, switch to use cto64() and adds a comments to make it
simpler and easier to be understood.

Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jason Wang 2017-01-20 14:35:28 +08:00 committed by Michael S. Tsirkin
parent ec42813028
commit 04eb6247eb
1 changed files with 9 additions and 1 deletions
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10
hw/i386/intel_iommu.c
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@ -1485,8 +1485,16 @@ static bool vtd_process_device_iotlb_desc(IntelIOMMUState *s,
goto done;
}
/* According to ATS spec table 2.4:
* S = 0, bits 15:12 = xxxx range size: 4K
* S = 1, bits 15:12 = xxx0 range size: 8K
* S = 1, bits 15:12 = xx01 range size: 16K
* S = 1, bits 15:12 = x011 range size: 32K
* S = 1, bits 15:12 = 0111 range size: 64K
* ...
*/
if (size) {
sz = 1 << (ctz64(~(addr | (VTD_PAGE_MASK_4K - 1))) + 1);
sz = (VTD_PAGE_SIZE * 2) << cto64(addr >> VTD_PAGE_SHIFT);
addr &= ~(sz - 1);
} else {
sz = VTD_PAGE_SIZE;