On 1/27/21 8:26 AM, Lu Baolu wrote:
+{
+ struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+ struct intel_iommu *iommu = domain_get_iommu(dmar_domain);
+
+ if (intel_iommu_strict)
+ return 0;
+
+ /*
+ * The flush queue implementation does not perform page-selective
+ * invalidations that are required for efficient TLB flushes in
virtual
+ * environments. The benefit of batching is likely to be much
lower than
+ * the overhead of synchronizing the virtual and physical IOMMU
+ * page-tables.
+ */
+ if (iommu && cap_caching_mode(iommu->cap)) {
+ pr_warn_once("IOMMU batching is partially disabled due to
virtualization");
+ return 0;
+ }
domain_get_iommu() only returns the first iommu, and could return NULL
when this is called before domain attaching to any device. A better
choice could be check caching mode globally and return false if caching
mode is supported on any iommu.
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
rcu_read_lock();
for_each_active_iommu(iommu, drhd) {
if (cap_caching_mode(iommu->cap))
return false;
We should unlock rcu before return here. Sorry!
}
rcu_read_unlock();
Best regards,
baolu
