iommu/vt-d: Fix PASID directory pointer coherency

[ Upstream commit 194b3348bdbb7db65375c72f3f774aee4cc6614e ]

On platforms that do not support IOMMU Extended capability bit 0
Page-walk Coherency, CPU caches are not snooped when IOMMU is accessing
any translation structures. IOMMU access goes only directly to
memory. Intel IOMMU code was missing a flush for the PASID table
directory that resulted in the unrecoverable fault as shown below.

This patch adds clflush calls whenever allocating and updating
a PASID table directory to ensure cache coherency.

On the reverse direction, there's no need to clflush the PASID directory
pointer when we deactivate a context entry in that IOMMU hardware will
not see the old PASID directory pointer after we clear the context entry.
PASID directory entries are also never freed once allocated.

 DMAR: DRHD: handling fault status reg 3
 DMAR: [DMA Read NO_PASID] Request device [00:0d.2] fault addr 0x1026a4000
       [fault reason 0x51] SM: Present bit in Directory Entry is clear
 DMAR: Dump dmar1 table entries for IOVA 0x1026a4000
 DMAR: scalable mode root entry: hi 0x0000000102448001, low 0x0000000101b3e001
 DMAR: context entry: hi 0x0000000000000000, low 0x0000000101b4d401
 DMAR: pasid dir entry: 0x0000000101b4e001
 DMAR: pasid table entry[0]: 0x0000000000000109
 DMAR: pasid table entry[1]: 0x0000000000000001
 DMAR: pasid table entry[2]: 0x0000000000000000
 DMAR: pasid table entry[3]: 0x0000000000000000
 DMAR: pasid table entry[4]: 0x0000000000000000
 DMAR: pasid table entry[5]: 0x0000000000000000
 DMAR: pasid table entry[6]: 0x0000000000000000
 DMAR: pasid table entry[7]: 0x0000000000000000
 DMAR: PTE not present at level 4

Cc: <stable@vger.kernel.org>
Fixes: 0bbeb01a4faf ("iommu/vt-d: Manage scalalble mode PASID tables")
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reported-by: Sukumar Ghorai <sukumar.ghorai@intel.com>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230209212843.1788125-1-jacob.jun.pan@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index e7cb0b8a73327083fbd7c9dd85382d3143cb7fb7..58f060006ba31c19b0336585390cbb59211f60b2 100644 (file)
--- a/drivers/iommu/intel-pasid.c
+++ b/drivers/iommu/intel-pasid.c
@@ -166,6 +166,9 @@ int intel_pasid_alloc_table(struct device *dev)
 attach_out:
        device_attach_pasid_table(info, pasid_table);
 
+       if (!ecap_coherent(info->iommu->ecap))
+               clflush_cache_range(pasid_table->table, size);
+
        return 0;
 }
 
@@ -250,6 +253,10 @@ struct pasid_entry *intel_pasid_get_entry(struct device *dev, int pasid)
 
                WRITE_ONCE(dir[dir_index].val,
                           (u64)virt_to_phys(entries) | PASID_PTE_PRESENT);
+               if (!ecap_coherent(info->iommu->ecap)) {
+                       clflush_cache_range(entries, VTD_PAGE_SIZE);
+                       clflush_cache_range(&dir[dir_index].val, sizeof(*dir));
+               }
        }
        spin_unlock(&pasid_lock);