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* [PATCH] iommu/amd: Remove dead code for exclusion ranges in IVMD
@ 2026-03-31 15:25 Yu Zhang
  2026-03-31 17:29 ` Jacob Pan
  0 siblings, 1 reply; 2+ messages in thread
From: Yu Zhang @ 2026-03-31 15:25 UTC (permalink / raw)
  To: iommu
  Cc: Joerg Roedel, Jason Gunthorpe, Jacob Pan, Suravee Suthikulpanit,
	Will Deacon, Robin Murphy, linux-kernel

Exclusion ranges in IVMD are treated as unity mappings with r&w
permissions since commit 0bbe4ced53e3 ("iommu/amd: Fix the
overwritten field in IVMD header"), using 1:1 mappings. And IOMMU
Exclusion Base & Range Limit Registers (0x0020/0x0028) are actually
no longer used.

As a result, several definitions and code paths became dead code:

 - exclusion_start/exclusion_length in struct amd_iommu are never
   assigned,
 - iommu_set_exclusion_range() always returns 0 now.
 - MMIO_EXCL_ENABLE_MASK & MMIO_EXCL_ALLOW_MASK are only used by
   the removed iommu_set_exclusion_range().
 - DEV_ENTRY_EX is no longer set in any DTE.
 - IOMMU_UNITY_MAP_FLAG_EXCL_RANGE is no longer set, thus the
   IOMMU_RESV_RESERVED branch in amd_iommu_get_resv_regions() is
   no longer reachable.

Just remove all of the dead code. No functional change.

Signed-off-by: Yu Zhang <zhangyu1@linux.microsoft.com>
---
 drivers/iommu/amd/amd_iommu_types.h | 12 ------------
 drivers/iommu/amd/init.c            | 23 -----------------------
 drivers/iommu/amd/iommu.c           |  3 ---
 3 files changed, 38 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index c685d3771436..a481d8cbd053 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -50,10 +50,6 @@
 #define MMIO_GET_BUS(x) (((x) & MMIO_RANGE_BUS_MASK) >> MMIO_RANGE_BUS_SHIFT)
 #define MMIO_MSI_NUM(x)	((x) & 0x1f)
 
-/* Flag masks for the AMD IOMMU exclusion range */
-#define MMIO_EXCL_ENABLE_MASK 0x01ULL
-#define MMIO_EXCL_ALLOW_MASK  0x02ULL
-
 /* Used offsets into the MMIO space */
 #define MMIO_DEV_TABLE_OFFSET   0x0000
 #define MMIO_CMD_BUF_OFFSET     0x0008
@@ -231,7 +227,6 @@
 #define DEV_ENTRY_IR            0x3d
 #define DEV_ENTRY_IW            0x3e
 #define DEV_ENTRY_NO_PAGE_FAULT	0x62
-#define DEV_ENTRY_EX            0x67
 #define DEV_ENTRY_SYSMGT1       0x68
 #define DEV_ENTRY_SYSMGT2       0x69
 #define DTE_DATA1_SYSMGT_MASK	GENMASK_ULL(41, 40)
@@ -384,8 +379,6 @@
 #define IOMMU_PROT_IR 0x01
 #define IOMMU_PROT_IW 0x02
 
-#define IOMMU_UNITY_MAP_FLAG_EXCL_RANGE	(1 << 2)
-
 /* IOMMU capabilities */
 #define IOMMU_CAP_IOTLB   24
 #define IOMMU_CAP_NPCACHE 26
@@ -680,11 +673,6 @@ struct amd_iommu {
 	/* pci domain of this IOMMU */
 	struct amd_iommu_pci_seg *pci_seg;
 
-	/* start of exclusion range of that IOMMU */
-	u64 exclusion_start;
-	/* length of exclusion range of that IOMMU */
-	u64 exclusion_length;
-
 	/* command buffer virtual address */
 	u8 *cmd_buf;
 	u32 cmd_buf_head;
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index f3fd7f39efb4..a33bf3f5ed8a 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -352,28 +352,6 @@ static void iommu_write_l2(struct amd_iommu *iommu, u8 address, u32 val)
  *
  ****************************************************************************/
 
-/*
- * This function set the exclusion range in the IOMMU. DMA accesses to the
- * exclusion range are passed through untranslated
- */
-static void iommu_set_exclusion_range(struct amd_iommu *iommu)
-{
-	u64 start = iommu->exclusion_start & PAGE_MASK;
-	u64 limit = (start + iommu->exclusion_length - 1) & PAGE_MASK;
-	u64 entry;
-
-	if (!iommu->exclusion_start)
-		return;
-
-	entry = start | MMIO_EXCL_ENABLE_MASK;
-	memcpy_toio(iommu->mmio_base + MMIO_EXCL_BASE_OFFSET,
-			&entry, sizeof(entry));
-
-	entry = limit;
-	memcpy_toio(iommu->mmio_base + MMIO_EXCL_LIMIT_OFFSET,
-			&entry, sizeof(entry));
-}
-
 static void iommu_set_cwwb_range(struct amd_iommu *iommu)
 {
 	u64 start = iommu_virt_to_phys((void *)iommu->cmd_sem);
@@ -2891,7 +2869,6 @@ static void early_enable_iommu(struct amd_iommu *iommu)
 	iommu_set_device_table(iommu);
 	iommu_enable_command_buffer(iommu);
 	iommu_enable_event_buffer(iommu);
-	iommu_set_exclusion_range(iommu);
 	iommu_enable_gt(iommu);
 	iommu_enable_ga(iommu);
 	iommu_enable_xt(iommu);
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 760d5f4623b5..4e7f5b993c65 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3076,9 +3076,6 @@ static void amd_iommu_get_resv_regions(struct device *dev,
 			prot |= IOMMU_READ;
 		if (entry->prot & IOMMU_PROT_IW)
 			prot |= IOMMU_WRITE;
-		if (entry->prot & IOMMU_UNITY_MAP_FLAG_EXCL_RANGE)
-			/* Exclusion range */
-			type = IOMMU_RESV_RESERVED;
 
 		region = iommu_alloc_resv_region(entry->address_start,
 						 length, prot, type,
-- 
2.52.0


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2026-03-31 15:25 [PATCH] iommu/amd: Remove dead code for exclusion ranges in IVMD Yu Zhang
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