Commit 206a73c1 authored by David Woodhouse's avatar David Woodhouse
Browse files

intel-iommu: Kill superfluous mapping_lock 



Since we're using cmpxchg64() anyway (because that's the only way to do
an atomic 64-bit store on i386), we might as well ditch the extra
locking and just use cmpxchg64() to ensure that we don't add the page
twice.

Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent c85994e4

drivers/pci/intel-iommu.c

+2 −10
Original line number Diff line number Diff line
@@ -267,7 +267,6 @@ struct dmar_domain { 
	struct iova_domain iovad;	/* iova's that belong to this domain */



	struct dma_pte	*pgd;		/* virtual address */

	spinlock_t	mapping_lock;	/* page table lock */

	int		gaw;		/* max guest address width */



	/* adjusted guest address width, 0 is level 2 30-bit */
@@ -701,13 +700,11 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain, 
	struct dma_pte *parent, *pte = NULL;

	int level = agaw_to_level(domain->agaw);

	int offset;

	unsigned long flags;



	BUG_ON(!domain->pgd);

	BUG_ON(addr_width < BITS_PER_LONG && pfn >> addr_width);

	parent = domain->pgd;



	spin_lock_irqsave(&domain->mapping_lock, flags);

	while (level > 0) {

		void *tmp_page;
@@ -721,11 +718,9 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain, 


			tmp_page = alloc_pgtable_page();



			if (!tmp_page) {

				spin_unlock_irqrestore(&domain->mapping_lock,

					flags);

			if (!tmp_page)

				return NULL;

			}



			domain_flush_cache(domain, tmp_page, VTD_PAGE_SIZE);

			pteval = (virt_to_dma_pfn(tmp_page) << VTD_PAGE_SHIFT) | DMA_PTE_READ | DMA_PTE_WRITE;

			if (cmpxchg64(&pte->val, 0ULL, pteval)) {
@@ -740,7 +735,6 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain, 
		level--;

	}



	spin_unlock_irqrestore(&domain->mapping_lock, flags);

	return pte;

}
@@ -1375,7 +1369,6 @@ static int domain_init(struct dmar_domain *domain, int guest_width) 
	unsigned long sagaw;



	init_iova_domain(&domain->iovad, DMA_32BIT_PFN);

	spin_lock_init(&domain->mapping_lock);

	spin_lock_init(&domain->iommu_lock);



	domain_reserve_special_ranges(domain);
@@ -3336,7 +3329,6 @@ static int md_domain_init(struct dmar_domain *domain, int guest_width) 
	int adjust_width;



	init_iova_domain(&domain->iovad, DMA_32BIT_PFN);

	spin_lock_init(&domain->mapping_lock);

	spin_lock_init(&domain->iommu_lock);



	domain_reserve_special_ranges(domain);

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