Patch "iommu/vt-d: Use second level for GPA->HPA translation" has been added to the 5.15-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: Use second level for GPA->HPA translation

to the 5.15-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-use-second-level-for-gpa-hpa-translation.patch
and it can be found in the queue-5.15 subdirectory.

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



commit a0a0957698459620a047567ae51f8683f94f8797
Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Date:   Thu Oct 14 13:38:35 2021 +0800

    iommu/vt-d: Use second level for GPA->HPA translation
    
    [ Upstream commit 032c5ee40e9fc68ed650a3f86f23259376ec93fc ]
    
    The IOMMU VT-d implementation uses the first level for GPA->HPA translation
    by default. Although both the first level and the second level could handle
    the DMA translation, they're different in some way. For example, the second
    level translation has separate controls for the Access/Dirty page tracking.
    With the first level translation, there's no such control. On the other
    hand, the second level translation has the page-level control for forcing
    snoop, but the first level only has global control with pasid granularity.
    
    This uses the second level for GPA->HPA translation so that we can provide
    a consistent hardware interface for use cases like dirty page tracking for
    live migration.
    
    Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20210926114535.923263-1-baolu.lu@xxxxxxxxxxxxxxx
    Link: https://lore.kernel.org/r/20211014053839.727419-6-baolu.lu@xxxxxxxxxxxxxxx
    Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
    Stable-dep-of: 257ec2907419 ("iommu/vt-d: Allow to use flush-queue when first level is default")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 6be0fb10cb8a9..850b0590c24a5 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1917,9 +1917,18 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
  * Check and return whether first level is used by default for
  * DMA translation.
  */
-static bool first_level_by_default(void)
+static bool first_level_by_default(unsigned int type)
 {
-	return scalable_mode_support() && intel_cap_flts_sanity();
+	/* Only SL is available in legacy mode */
+	if (!scalable_mode_support())
+		return false;
+
+	/* Only level (either FL or SL) is available, just use it */
+	if (intel_cap_flts_sanity() ^ intel_cap_slts_sanity())
+		return intel_cap_flts_sanity();
+
+	/* Both levels are available, decide it based on domain type */
+	return type != IOMMU_DOMAIN_UNMANAGED;
 }
 
 static struct dmar_domain *alloc_domain(unsigned int type)
@@ -1932,7 +1941,7 @@ static struct dmar_domain *alloc_domain(unsigned int type)
 
 	memset(domain, 0, sizeof(*domain));
 	domain->nid = NUMA_NO_NODE;
-	if (first_level_by_default())
+	if (first_level_by_default(type))
 		domain->flags |= DOMAIN_FLAG_USE_FIRST_LEVEL;
 	domain->has_iotlb_device = false;
 	INIT_LIST_HEAD(&domain->devices);