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| author | David Woodhouse <dwmw2@infradead.org> | 2014-03-11 17:10:29 -0700 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2014-03-19 17:25:48 +0000 |
| commit | d05019608746240d86a406fbf8d8c1fc71a87101 (patch) | |
| tree | 8a5732ae72564c14dfa1013f7904be53b911734c /drivers/iommu | |
| parent | 214e39aa36c9c02355d388f20d83b93fc2fa7298 (diff) | |
| download | linux-d05019608746240d86a406fbf8d8c1fc71a87101.tar.gz linux-d05019608746240d86a406fbf8d8c1fc71a87101.tar.bz2 linux-d05019608746240d86a406fbf8d8c1fc71a87101.zip | |
iommu/vt-d: Be less pessimistic about domain coherency where possible
In commit 2e12bc29 ("intel-iommu: Default to non-coherent for domains
unattached to iommus") we decided to err on the side of caution and
always assume that it's possible that a device will be attached which is
behind a non-coherent IOMMU.
In some cases, however, that just *cannot* happen. If there *are* no
IOMMUs in the system which are non-coherent, then we don't need to do
it. And flushing the dcache is a *significant* performance hit.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers/iommu')
| -rw-r--r-- | drivers/iommu/intel-iommu.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index c3d4bc91a189..1599cb1e041c 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -592,18 +592,31 @@ static struct intel_iommu *domain_get_iommu(struct dmar_domain *domain) static void domain_update_iommu_coherency(struct dmar_domain *domain) { - int i; - - i = find_first_bit(domain->iommu_bmp, g_num_of_iommus); + struct dmar_drhd_unit *drhd; + struct intel_iommu *iommu; + int i, found = 0; - domain->iommu_coherency = i < g_num_of_iommus ? 1 : 0; + domain->iommu_coherency = 1; for_each_set_bit(i, domain->iommu_bmp, g_num_of_iommus) { + found = 1; if (!ecap_coherent(g_iommus[i]->ecap)) { domain->iommu_coherency = 0; break; } } + if (found) + return; + + /* No hardware attached; use lowest common denominator */ + rcu_read_lock(); + for_each_active_iommu(iommu, drhd) { + if (!ecap_coherent(iommu->ecap)) { + domain->iommu_coherency = 0; + break; + } + } + rcu_read_unlock(); } static void domain_update_iommu_snooping(struct dmar_domain *domain) |