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| author | Uros Bizjak <ubizjak@gmail.com> | 2024-04-24 10:16:28 +0300 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2024-04-26 12:57:36 +0300 |
| commit | 9e7ee0f045395dc8aa55fbdc164c062484f4c88d (patch) | |
| tree | 3b06b0fe95ec1e9d3fd6d66e9e236809ea5b543a /drivers/iommu/intel | |
| parent | a770ccd91d99f997e023b554d9e2033ce79e019e (diff) | |
| download | linux-9e7ee0f045395dc8aa55fbdc164c062484f4c88d.tar.xz | |
iommu/vt-d: Use try_cmpxchg64{,_local}() in iommu.c
Replace this pattern in iommu.c:
cmpxchg64{,_local}(*ptr, 0, new) != 0
... with the simpler and faster:
!try_cmpxchg64{,_local}(*ptr, &tmp, new)
The x86 CMPXCHG instruction returns success in the ZF flag, so this change
saves a compare after the CMPXCHG.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240414162454.49584-1-ubizjak@gmail.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu/intel')
| -rw-r--r-- | drivers/iommu/intel/iommu.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index a7ecd90303dc..4a2afe89b464 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -865,7 +865,7 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain, break; if (!dma_pte_present(pte)) { - uint64_t pteval; + uint64_t pteval, tmp; tmp_page = alloc_pgtable_page(domain->nid, gfp); @@ -877,7 +877,8 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain, if (domain->use_first_level) pteval |= DMA_FL_PTE_XD | DMA_FL_PTE_US | DMA_FL_PTE_ACCESS; - if (cmpxchg64(&pte->val, 0ULL, pteval)) + tmp = 0ULL; + if (!try_cmpxchg64(&pte->val, &tmp, pteval)) /* Someone else set it while we were thinking; use theirs. */ free_pgtable_page(tmp_page); else @@ -2128,8 +2129,8 @@ __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn, /* We don't need lock here, nobody else * touches the iova range */ - tmp = cmpxchg64_local(&pte->val, 0ULL, pteval); - if (tmp) { + tmp = 0ULL; + if (!try_cmpxchg64_local(&pte->val, &tmp, pteval)) { static int dumps = 5; pr_crit("ERROR: DMA PTE for vPFN 0x%lx already set (to %llx not %llx)\n", iov_pfn, tmp, (unsigned long long)pteval); |