iommu/amd: Preserve default DTE fields when updating Host Page Table Root

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>
Reviewed-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20250106191413.3107140-1-alejandro.j.jimenez@oracle.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index b48a72bd7b23df7adb1a2c81a2440d084daff2cd..cd5116d8c3b2831655c1966e203fa90b9de6fae5 100644 (file)
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2043,12 +2043,12 @@ 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.