# 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;
}
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