iommu/vt-d: Fix PASID directory pointer coherency

commit 194b3348 upstream.

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: 0bbeb01a

 ("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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>