[PATCH 1/1] iommu/amd: Preserve default DTE fields when updating Host Page Table Root

[Alejandro Jimenez <alejandro.j.jimenez@oracle.com>]

When updating the page table root field on the DTE, avoid overwriting any
bits that are already set. The earlier call to make_clear_dte() writes
default values that all DTEs must have set (currently DTE[V]), and those
must be preserved.

Currently this doesn't cause problems since the page table root update is
the first field that is set after make_clear_dte() is called, and
DTE_FLAG_V is set again later along with the permission bits (IR/IW).
Remove this redundant assignment too.

Fixes: fd5dff9de4be ("iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers")
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
---
 drivers/iommu/amd/iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 20177e18eb0d..a8c17b602c95 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2052,12 +2052,12 @@ static void set_dte_entry(struct amd_iommu *iommu,
 	make_clear_dte(dev_data, dte, &new);
 
 	if (domain->iop.mode != PAGE_MODE_NONE)
-		new.data[0] = iommu_virt_to_phys(domain->iop.root);
+		new.data[0] |= iommu_virt_to_phys(domain->iop.root);
 
 	new.data[0] |= (domain->iop.mode & DEV_ENTRY_MODE_MASK)
 		    << DEV_ENTRY_MODE_SHIFT;
 
-	new.data[0] |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V;
+	new.data[0] |= DTE_FLAG_IR | DTE_FLAG_IW;
 
 	/*
 	 * When SNP is enabled, we can only support TV=1 with non-zero domain ID.

base-commit: 1f37ef785d54b27e304c189038697a845259408a
-- 
2.39.3