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authorAlex Williamson <alex.williamson@redhat.com>2011-11-11 17:26:44 -0700
committerJoerg Roedel <joerg.roedel@amd.com>2012-09-18 16:17:31 +0200
commit2e12bc29fc5a12242d68e11875db3dd58efad9ff (patch)
tree58eb9ec98346b857787a45d206d9e75d3aaab72a /drivers/iommu
parent5698bd757d55b1bb87edd1a9744ab09c142abfc2 (diff)
intel-iommu: Default to non-coherent for domains unattached to iommus
domain_update_iommu_coherency() currently defaults to setting domains as coherent when the domain is not attached to any iommus. This allows for a window in domain_context_mapping_one() where such a domain can update context entries non-coherently, and only after update the domain capability to clear iommu_coherency. This can be seen using KVM device assignment on VT-d systems that do not support coherency in the ecap register. When a device is added to a guest, a domain is created (iommu_coherency = 0), the device is attached, and ranges are mapped. If we then hot unplug the device, the coherency is updated and set to the default (1) since no iommus are attached to the domain. A subsequent attach of a device makes use of the same dmar domain (now marked coherent) updates context entries with coherency enabled, and only disables coherency as the last step in the process. To fix this, switch domain_update_iommu_coherency() to use the safer, non-coherent default for domains not attached to iommus. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Tested-by: Donald Dutile <ddutile@redhat.com> Acked-by: Donald Dutile <ddutile@redhat.com> Acked-by: Chris Wright <chrisw@sous-sol.org> Cc: stable@vger.kernel.org Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/intel-iommu.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 2297ec193eb..cb9e1146b02 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -589,7 +589,9 @@ static void domain_update_iommu_coherency(struct dmar_domain *domain)
{
int i;
- domain->iommu_coherency = 1;
+ i = find_first_bit(domain->iommu_bmp, g_num_of_iommus);
+
+ domain->iommu_coherency = i < g_num_of_iommus ? 1 : 0;
for_each_set_bit(i, domain->iommu_bmp, g_num_of_iommus) {
if (!ecap_coherent(g_iommus[i]->ecap)) {