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| author | Uros Bizjak <ubizjak@gmail.com> | 2024-05-22 10:26:48 +0200 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2024-06-25 14:20:53 +0200 |
| commit | 5c555f1f1c31f7dd60a7697be9bb0e98706bb10a (patch) | |
| tree | eb1b86466a506f7949a2d34ee6528ddf44c32b0b /drivers/iommu | |
| parent | Linux 6.10-rc3 (diff) | |
| download | linux-5c555f1f1c31f7dd60a7697be9bb0e98706bb10a.tar.xz linux-5c555f1f1c31f7dd60a7697be9bb0e98706bb10a.zip | |
iommu/vt-d: Use try_cmpxchg64() in intel_pasid_get_entry()
Use try_cmpxchg64() instead of cmpxchg64 (*ptr, old, new) != old in
intel_pasid_get_entry(). cmpxchg returns success in ZF flag, so
this change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).
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: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20240522082729.971123-2-ubizjak@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
| -rw-r--r-- | drivers/iommu/intel/pasid.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c index abce19e2ad6f..9bf45bc4b967 100644 --- a/drivers/iommu/intel/pasid.c +++ b/drivers/iommu/intel/pasid.c @@ -146,6 +146,8 @@ static struct pasid_entry *intel_pasid_get_entry(struct device *dev, u32 pasid) retry: entries = get_pasid_table_from_pde(&dir[dir_index]); if (!entries) { + u64 tmp; + entries = iommu_alloc_page_node(info->iommu->node, GFP_ATOMIC); if (!entries) return NULL; @@ -156,8 +158,9 @@ retry: * clear. However, this entry might be populated by others * while we are preparing it. Use theirs with a retry. */ - if (cmpxchg64(&dir[dir_index].val, 0ULL, - (u64)virt_to_phys(entries) | PASID_PTE_PRESENT)) { + tmp = 0ULL; + if (!try_cmpxchg64(&dir[dir_index].val, &tmp, + (u64)virt_to_phys(entries) | PASID_PTE_PRESENT)) { iommu_free_page(entries); goto retry; } |