linux-kernel - [PATCH v4 14/16] iommu/amd: Refactor persistent DTE bits programming into amd_iommu_make_clear

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Message-ID: <20251021014324.5837-15-suravee.suthikulpanit@amd.com>
Date: Tue, 21 Oct 2025 01:43:22 +0000
From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To: <jgg@...dia.com>, <nicolinc@...dia.com>
CC: <linux-kernel@...r.kernel.org>, <robin.murphy@....com>, <will@...nel.org>,
	<joro@...tes.org>, <kevin.tian@...el.com>, <jsnitsel@...hat.com>,
	<vasant.hegde@....com>, <iommu@...ts.linux.dev>, <santosh.shukla@....com>,
	<sairaj.arunkodilkar@....com>, <jon.grimm@....com>,
	<prashanthpra@...gle.com>, <wvw@...gle.com>, <wnliu@...gle.com>,
	<gptran@...gle.com>, <kpsingh@...gle.com>, <joao.m.martins@...cle.com>,
	<alejandro.j.jimenez@...cle.com>, Suravee Suthikulpanit
	<suravee.suthikulpanit@....com>
Subject: [PATCH v4 14/16] iommu/amd: Refactor persistent DTE bits programming into amd_iommu_make_clear_dte()

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@...dia.com>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....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 e4db6f304599..e3330f3b8c14 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2078,7 +2078,6 @@ 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;
@@ -2119,16 +2118,6 @@ 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