Patch "iommu/vt-d: Fix PASID directory pointer coherency" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    iommu/vt-d: Fix PASID directory pointer coherency

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     iommu-vt-d-fix-pasid-directory-pointer-coherency.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 599d2b068fe90620f816cc0148ee88d52e29ff16
Author: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Date:   Thu Feb 16 21:08:15 2023 +0800

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

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index e7cb0b8a73327..58f060006ba31 100644
--- 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);