Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-12-17 00:21:32 +00:00
Code Issues Packages Projects Releases Wiki Activity

intel-iommu: Default to non-coherent for domains unattached to iommus

Browse Source 
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>
This commit is contained in:
Alex Williamson 2011-11-11 17:26:44 -07:00 committed by Joerg Roedel
parent 5698bd757d
commit 2e12bc29fc
1 changed files with 3 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/iommu/intel-iommu.c
View File

@ -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)) {