To help avoid duplicate logic when programing DTE for nested translation.

Note that this commit changes behavior of detached and blocking modes,
where DTE bit fields for interrupt pass-through (i.e. Lint0, Lint1, NMI,
INIT, ExtInt) and System management message could be affected.
These DTE bits are specified in the IVRS table for specific devices,
and should be persistent.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu.h | 13 +++++++++++++
 drivers/iommu/amd/iommu.c     | 11 -----------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 3730d8bbe6dc..cfb63de7732a 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -197,9 +197,22 @@ void amd_iommu_update_dte256(struct amd_iommu *iommu,
 static inline void
 amd_iommu_make_clear_dte(struct iommu_dev_data *dev_data, struct dev_table_entry *new)
 {
+	struct dev_table_entry *initial_dte;
+	struct amd_iommu *iommu = get_amd_iommu_from_dev(dev_data->dev);
+
 	/* All existing DTE must have V bit set */
 	new->data128[0] = DTE_FLAG_V;
 	new->data128[1] = 0;
+
+	/*
+	 * Restore cached persistent DTE bits, which can be set by information
+	 * in IVRS table. See set_dev_entry_from_acpi().
+	 */
+	initial_dte = amd_iommu_get_ivhd_dte_flags(iommu->pci_seg->id, dev_data->devid);
+	if (initial_dte) {
+		new->data128[0] |= initial_dte->data128[0];
+		new->data128[1] |= initial_dte->data128[1];
+	}
 }
 
 /* NESTED */
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index e489e360bb77..ffb1adfd75c0 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2049,7 +2049,6 @@ static void set_dte_entry(struct amd_iommu *iommu,
 {
 	u16 domid;
 	u32 old_domid;
-	struct dev_table_entry *initial_dte;
 	struct dev_table_entry new = {};
 	struct protection_domain *domain = dev_data->domain;
 	struct gcr3_tbl_info *gcr3_info = &dev_data->gcr3_info;
@@ -2090,16 +2089,6 @@ static void set_dte_entry(struct amd_iommu *iommu,
 	old_domid = READ_ONCE(dte->data[1]) & DTE_DOMID_MASK;
 	new.data[1] |= domid;
 
-	/*
-	 * Restore cached persistent DTE bits, which can be set by information
-	 * in IVRS table. See set_dev_entry_from_acpi().
-	 */
-	initial_dte = amd_iommu_get_ivhd_dte_flags(iommu->pci_seg->id, dev_data->devid);
-	if (initial_dte) {
-		new.data128[0] |= initial_dte->data128[0];
-		new.data128[1] |= initial_dte->data128[1];
-	}
-
 	set_dte_gcr3_table(iommu, dev_data, &new);
 
 	amd_iommu_update_dte256(iommu, dev_data, &new);
-- 
2.34.1

On Thu, Oct 09, 2025 at 11:57:53PM +0000, Suravee Suthikulpanit wrote:
> To help avoid duplicate logic when programing DTE for nested translation.
> 
> Note that this commit changes behavior of detached and blocking
> modes,

We don't actually have "detached", what this changes is a small time
window while the AMD driver is changing domains during attach, and the
blocking domain.

> where DTE bit fields for interrupt pass-through (i.e. Lint0, Lint1, NMI,
> INIT, ExtInt) and System management message could be affected.
> These DTE bits are specified in the IVRS table for specific devices,
> and should be persistent.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
>  drivers/iommu/amd/amd_iommu.h | 13 +++++++++++++
>  drivers/iommu/amd/iommu.c     | 11 -----------
>  2 files changed, 13 insertions(+), 11 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason