[PATCH v6 11/13] iommu/amd: Refactor persistent DTE bits programming into amd_iommu_make_clear_dte()

Suravee Suthikulpanit
2026-01-15T06:09:43Z

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

Note that this commit changes behavior of when the IOMMU driver is
switching domain 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>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Nicolin Chen <nicolinc@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 aa29afe96e90..00fc9c6073de 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -197,9 +197,22 @@ void amd_iommu_update_dte(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 e33076b99aac..dafd34465fc0 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2106,7 +2106,6 @@ 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;
@@ -2164,16 +2163,6 @@ 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_dte(iommu, dev_data, &new);
--
2.34.1