[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] VT-d: eliminate a mis-use of pcidevs_lock
# HG changeset patch # User Jan Beulich <jbeulich@xxxxxxxx> # Date 1316712704 -3600 # Node ID 571b6e90dfb463b4a56b2a1c8d7d00f7741ca692 # Parent 47ec1d405af9e9c0491681c50bb622d1c1f0904d VT-d: eliminate a mis-use of pcidevs_lock dma_pte_clear_one() shouldn't acquire this global lock for the purpose of processing a per-domain list. Furthermore the function a few lines earlier has a comment stating that acquiring pcidevs_lock isn't necessary here (whether that's really correct is another question). Use the domain's mappin_lock instead to protect the mapped_rmrrs list. Fold domain_rmrr_mapped() into its sole caller so that the otherwise implicit dependency on pcidevs_lock there becomes more obvious (see the comment there). Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- diff -r 47ec1d405af9 -r 571b6e90dfb4 xen/drivers/passthrough/vtd/iommu.c --- a/xen/drivers/passthrough/vtd/iommu.c Thu Sep 22 18:31:02 2011 +0100 +++ b/xen/drivers/passthrough/vtd/iommu.c Thu Sep 22 18:31:44 2011 +0100 @@ -589,7 +589,6 @@ u64 pg_maddr; int flush_dev_iotlb; int iommu_domid; - struct list_head *rmrr_list, *tmp; struct mapped_rmrr *mrmrr; spin_lock(&hd->mapping_lock); @@ -636,10 +635,9 @@ /* if the cleared address is between mapped RMRR region, * remove the mapped RMRR */ - spin_lock(&pcidevs_lock); - list_for_each_safe ( rmrr_list, tmp, &hd->mapped_rmrrs ) + spin_lock(&hd->mapping_lock); + list_for_each_entry ( mrmrr, &hd->mapped_rmrrs, list ) { - mrmrr = list_entry(rmrr_list, struct mapped_rmrr, list); if ( addr >= mrmrr->base && addr <= mrmrr->end ) { list_del(&mrmrr->list); @@ -647,7 +645,7 @@ break; } } - spin_unlock(&pcidevs_lock); + spin_unlock(&hd->mapping_lock); } static void iommu_free_pagetable(u64 pt_maddr, int level) @@ -1824,22 +1822,6 @@ hd->pgd_maddr = pagetable_get_paddr(pagetable_from_mfn(pgd_mfn)); } -static int domain_rmrr_mapped(struct domain *d, - struct acpi_rmrr_unit *rmrr) -{ - struct hvm_iommu *hd = domain_hvm_iommu(d); - struct mapped_rmrr *mrmrr; - - list_for_each_entry( mrmrr, &hd->mapped_rmrrs, list ) - { - if ( mrmrr->base == rmrr->base_address && - mrmrr->end == rmrr->end_address ) - return 1; - } - - return 0; -} - static int rmrr_identity_mapping(struct domain *d, struct acpi_rmrr_unit *rmrr) { @@ -1851,8 +1833,16 @@ ASSERT(spin_is_locked(&pcidevs_lock)); ASSERT(rmrr->base_address < rmrr->end_address); - if ( domain_rmrr_mapped(d, rmrr) ) - return 0; + /* + * No need to acquire hd->mapping_lock, as the only theoretical race is + * with the insertion below (impossible due to holding pcidevs_lock). + */ + list_for_each_entry( mrmrr, &hd->mapped_rmrrs, list ) + { + if ( mrmrr->base == rmrr->base_address && + mrmrr->end == rmrr->end_address ) + return 0; + } base = rmrr->base_address & PAGE_MASK_4K; base_pfn = base >> PAGE_SHIFT_4K; @@ -1872,7 +1862,9 @@ return -ENOMEM; mrmrr->base = rmrr->base_address; mrmrr->end = rmrr->end_address; + spin_lock(&hd->mapping_lock); list_add_tail(&mrmrr->list, &hd->mapped_rmrrs); + spin_unlock(&hd->mapping_lock); return 0; } _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-changelog
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