[PATCH v7 00/10] iommu/amd: Use 128-bit cmpxchg operation to update DTE

[PATCH v7 00/10] iommu/amd: Use 128-bit cmpxchg operation to update DTE

[Suravee Suthikulpanit]

This series modifies current implementation to use 128-bit cmpxchg to
update DTE when needed as specified in the AMD I/O Virtualization
Techonology (IOMMU) Specification.

Please note that I have verified with the hardware designer, and they have
confirmed that the IOMMU hardware has always been implemented with 256-bit
read. The next revision of the IOMMU spec will be updated to correctly
describe this part.  Therefore, I have updated the implementation to avoid
unnecessary flushing.

Changes in v7:

* Patch 1: Newly added

* Patch 4: Newly added
  Replace struct dev_data.initial_dte with global amd_ivhd_dev_flags_list
  to store persistent DTE fields for devices. The previous design has a major
  drawbacks where it needs to allocate the struct dev_data unnecessarily for
  non-existing devices to store initial DTE values.

* Patch 6: Clean up per Jason

* Patch 10: Newly added

v6: https://lore.kernel.org/lkml/20241016051756.4317-1-suravee.suthikulpanit@amd.com/ 
v5: https://lore.kernel.org/lkml/20241007041353.4756-1-suravee.suthikulpanit@amd.com/
v4: https://lore.kernel.org/lkml/20240916171805.324292-1-suravee.suthikulpanit@amd.com/
v3: https://lore.kernel.org/lkml/20240906121308.5013-1-suravee.suthikulpanit@amd.com/
v2: https://lore.kernel.org/lkml/20240829180726.5022-1-suravee.suthikulpanit@amd.com/
v1: https://lore.kernel.org/lkml/20240819161839.4657-1-suravee.suthikulpanit@amd.com/

Thanks,
Suravee

Suravee Suthikulpanit (9):
  iommu/amd: Misc ACPI IVRS debug info clean up
  iommu/amd: Disable AMD IOMMU if CMPXCHG16B feature is not supported
  iommu/amd: Introduce struct ivhd_dte_flags to store persistent DTE
    flags
  iommu/amd: Introduce helper function to update 256-bit DTE
  iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers
  iommu/amd: Introduce helper function get_dte256()
  iommu/amd: Modify clear_dte_entry() to avoid in-place update
  iommu/amd: Lock DTE before updating the entry with WRITE_ONCE()
  iommu/amd: Remove amd_iommu_apply_erratum_63()

Uros Bizjak (1):
  asm/rwonce: Introduce [READ|WRITE]_ONCE() support for __int128

 drivers/iommu/amd/amd_iommu.h       |   4 +-
 drivers/iommu/amd/amd_iommu_types.h |  40 ++-
 drivers/iommu/amd/init.c            | 224 +++++++++--------
 drivers/iommu/amd/iommu.c           | 370 ++++++++++++++++++++--------
 include/asm-generic/rwonce.h        |   2 +-
 include/linux/compiler_types.h      |   8 +-
 6 files changed, 434 insertions(+), 214 deletions(-)

-- 
2.34.1

[PATCH v7 01/10] iommu/amd: Misc ACPI IVRS debug info clean up

[Suravee Suthikulpanit]

* Remove redundant AMD-Vi prefix.
* Print IVHD device entry settings field using hex value.
* Print root device of IVHD ACPI device entry using hex value.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu_types.h |  2 +-
 drivers/iommu/amd/init.c            | 35 +++++++++++++----------------
 2 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 601fb4ee6900..dadc65808951 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -468,7 +468,7 @@ extern bool amd_iommu_dump;
 #define DUMP_printk(format, arg...)				\
 	do {							\
 		if (amd_iommu_dump)				\
-			pr_info("AMD-Vi: " format, ## arg);	\
+			pr_info(format, ## arg);	\
 	} while(0);
 
 /* global flag if IOMMUs cache non-present entries */
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 43131c3a2172..aa9bf81a6ec9 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -1243,7 +1243,7 @@ static int __init add_acpi_hid_device(u8 *hid, u8 *uid, u32 *devid,
 	entry->cmd_line	= cmd_line;
 	entry->root_devid = (entry->devid & (~0x7));
 
-	pr_info("%s, add hid:%s, uid:%s, rdevid:%d\n",
+	pr_info("%s, add hid:%s, uid:%s, rdevid:%#x\n",
 		entry->cmd_line ? "cmd" : "ivrs",
 		entry->hid, entry->uid, entry->root_devid);
 
@@ -1335,15 +1335,14 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 		switch (e->type) {
 		case IVHD_DEV_ALL:
 
-			DUMP_printk("  DEV_ALL\t\t\tflags: %02x\n", e->flags);
+			DUMP_printk("  DEV_ALL\t\t\tsetting: %#02x\n", e->flags);
 
 			for (dev_i = 0; dev_i <= pci_seg->last_bdf; ++dev_i)
 				set_dev_entry_from_acpi(iommu, dev_i, e->flags, 0);
 			break;
 		case IVHD_DEV_SELECT:
 
-			DUMP_printk("  DEV_SELECT\t\t\t devid: %04x:%02x:%02x.%x "
-				    "flags: %02x\n",
+			DUMP_printk("  DEV_SELECT\t\t\tdevid: %04x:%02x:%02x.%x flags: %#02x\n",
 				    seg_id, PCI_BUS_NUM(e->devid),
 				    PCI_SLOT(e->devid),
 				    PCI_FUNC(e->devid),
@@ -1354,8 +1353,7 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			break;
 		case IVHD_DEV_SELECT_RANGE_START:
 
-			DUMP_printk("  DEV_SELECT_RANGE_START\t "
-				    "devid: %04x:%02x:%02x.%x flags: %02x\n",
+			DUMP_printk("  DEV_SELECT_RANGE_START\tdevid: %04x:%02x:%02x.%x flags: %#02x\n",
 				    seg_id, PCI_BUS_NUM(e->devid),
 				    PCI_SLOT(e->devid),
 				    PCI_FUNC(e->devid),
@@ -1368,8 +1366,7 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			break;
 		case IVHD_DEV_ALIAS:
 
-			DUMP_printk("  DEV_ALIAS\t\t\t devid: %04x:%02x:%02x.%x "
-				    "flags: %02x devid_to: %02x:%02x.%x\n",
+			DUMP_printk("  DEV_ALIAS\t\t\tdevid: %04x:%02x:%02x.%x flags: %#02x devid_to: %02x:%02x.%x\n",
 				    seg_id, PCI_BUS_NUM(e->devid),
 				    PCI_SLOT(e->devid),
 				    PCI_FUNC(e->devid),
@@ -1386,9 +1383,7 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			break;
 		case IVHD_DEV_ALIAS_RANGE:
 
-			DUMP_printk("  DEV_ALIAS_RANGE\t\t "
-				    "devid: %04x:%02x:%02x.%x flags: %02x "
-				    "devid_to: %04x:%02x:%02x.%x\n",
+			DUMP_printk("  DEV_ALIAS_RANGE\t\tdevid: %04x:%02x:%02x.%x flags: %#02x devid_to: %04x:%02x:%02x.%x\n",
 				    seg_id, PCI_BUS_NUM(e->devid),
 				    PCI_SLOT(e->devid),
 				    PCI_FUNC(e->devid),
@@ -1405,8 +1400,7 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			break;
 		case IVHD_DEV_EXT_SELECT:
 
-			DUMP_printk("  DEV_EXT_SELECT\t\t devid: %04x:%02x:%02x.%x "
-				    "flags: %02x ext: %08x\n",
+			DUMP_printk("  DEV_EXT_SELECT\t\tdevid: %04x:%02x:%02x.%x flags: %#02x ext: %08x\n",
 				    seg_id, PCI_BUS_NUM(e->devid),
 				    PCI_SLOT(e->devid),
 				    PCI_FUNC(e->devid),
@@ -1418,8 +1412,7 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			break;
 		case IVHD_DEV_EXT_SELECT_RANGE:
 
-			DUMP_printk("  DEV_EXT_SELECT_RANGE\t devid: "
-				    "%04x:%02x:%02x.%x flags: %02x ext: %08x\n",
+			DUMP_printk("  DEV_EXT_SELECT_RANGE\tdevid: %04x:%02x:%02x.%x flags: %#02x ext: %08x\n",
 				    seg_id, PCI_BUS_NUM(e->devid),
 				    PCI_SLOT(e->devid),
 				    PCI_FUNC(e->devid),
@@ -1432,7 +1425,7 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			break;
 		case IVHD_DEV_RANGE_END:
 
-			DUMP_printk("  DEV_RANGE_END\t\t devid: %04x:%02x:%02x.%x\n",
+			DUMP_printk("  DEV_RANGE_END\t\tdevid: %04x:%02x:%02x.%x\n",
 				    seg_id, PCI_BUS_NUM(e->devid),
 				    PCI_SLOT(e->devid),
 				    PCI_FUNC(e->devid));
@@ -1465,11 +1458,12 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			else
 				var = "UNKNOWN";
 
-			DUMP_printk("  DEV_SPECIAL(%s[%d])\t\tdevid: %04x:%02x:%02x.%x\n",
+			DUMP_printk("  DEV_SPECIAL(%s[%d])\t\tdevid: %04x:%02x:%02x.%x, flags: %#02x\n",
 				    var, (int)handle,
 				    seg_id, PCI_BUS_NUM(devid),
 				    PCI_SLOT(devid),
-				    PCI_FUNC(devid));
+				    PCI_FUNC(devid),
+				    e->flags);
 
 			ret = add_special_device(type, handle, &devid, false);
 			if (ret)
@@ -1529,11 +1523,12 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 			}
 
 			devid = PCI_SEG_DEVID_TO_SBDF(seg_id, e->devid);
-			DUMP_printk("  DEV_ACPI_HID(%s[%s])\t\tdevid: %04x:%02x:%02x.%x\n",
+			DUMP_printk("  DEV_ACPI_HID(%s[%s])\t\tdevid: %04x:%02x:%02x.%x, flags: %#02x\n",
 				    hid, uid, seg_id,
 				    PCI_BUS_NUM(devid),
 				    PCI_SLOT(devid),
-				    PCI_FUNC(devid));
+				    PCI_FUNC(devid),
+				    e->flags);
 
 			flags = e->flags;
 
-- 
2.34.1

[PATCH v7 02/10] iommu/amd: Disable AMD IOMMU if CMPXCHG16B feature is not supported

[Suravee Suthikulpanit]

According to the AMD IOMMU spec, IOMMU hardware reads the entire DTE
in a single 256-bit transaction. It is recommended to update DTE using
128-bit operation followed by an INVALIDATE_DEVTAB_ENTYRY command when
the IV=1b or V=1b before the change.

According to the AMD BIOS and Kernel Developer's Guide (BDKG) dated back
to family 10h Processor [1], which is the first introduction of AMD IOMMU,
AMD processor always has CPUID Fn0000_0001_ECX[CMPXCHG16B]=1.
Therefore, it is safe to assume cmpxchg128 is available with all AMD
processor w/ IOMMU.

In addition, the CMPXCHG16B feature has already been checked separately
before enabling the GA, XT, and GAM modes. Consolidate the detection logic,
and fail the IOMMU initialization if the feature is not supported.

[1] https://www.amd.com/content/dam/amd/en/documents/archived-tech-docs/programmer-references/31116.pdf

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/init.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index aa9bf81a6ec9..8868838139df 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -1759,13 +1759,8 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h,
 		else
 			iommu->mmio_phys_end = MMIO_CNTR_CONF_OFFSET;
 
-		/*
-		 * Note: GA (128-bit IRTE) mode requires cmpxchg16b supports.
-		 * GAM also requires GA mode. Therefore, we need to
-		 * check cmpxchg16b support before enabling it.
-		 */
-		if (!boot_cpu_has(X86_FEATURE_CX16) ||
-		    ((h->efr_attr & (0x1 << IOMMU_FEAT_GASUP_SHIFT)) == 0))
+		/* GAM requires GA mode. */
+		if ((h->efr_attr & (0x1 << IOMMU_FEAT_GASUP_SHIFT)) == 0)
 			amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_LEGACY;
 		break;
 	case 0x11:
@@ -1775,13 +1770,8 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h,
 		else
 			iommu->mmio_phys_end = MMIO_CNTR_CONF_OFFSET;
 
-		/*
-		 * Note: GA (128-bit IRTE) mode requires cmpxchg16b supports.
-		 * XT, GAM also requires GA mode. Therefore, we need to
-		 * check cmpxchg16b support before enabling them.
-		 */
-		if (!boot_cpu_has(X86_FEATURE_CX16) ||
-		    ((h->efr_reg & (0x1 << IOMMU_EFR_GASUP_SHIFT)) == 0)) {
+		/* XT and GAM require GA mode. */
+		if ((h->efr_reg & (0x1 << IOMMU_EFR_GASUP_SHIFT)) == 0) {
 			amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_LEGACY;
 			break;
 		}
@@ -3046,6 +3036,11 @@ static int __init early_amd_iommu_init(void)
 		return -EINVAL;
 	}
 
+	if (!boot_cpu_has(X86_FEATURE_CX16)) {
+		pr_err("Failed to initialize. The CMPXCHG16B feature is required.\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * Validate checksum here so we don't need to do it when
 	 * we actually parse the table
-- 
2.34.1

[PATCH v7 03/10] asm/rwonce: Introduce [READ|WRITE]_ONCE() support for __int128

[Suravee Suthikulpanit]

From: Uros Bizjak <ubizjak@gmail.com>

Currently, [READ|WRITE]_ONCE() do not support variable of type __int128.
Re-define "__dword_type" from type "long long" to __int128 if supported.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 include/asm-generic/rwonce.h   | 2 +-
 include/linux/compiler_types.h | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h
index 8d0a6280e982..8bf942ad5ef3 100644
--- a/include/asm-generic/rwonce.h
+++ b/include/asm-generic/rwonce.h
@@ -33,7 +33,7 @@
  * (e.g. a virtual address) and a strong prevailing wind.
  */
 #define compiletime_assert_rwonce_type(t)					\
-	compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long),	\
+	compiletime_assert(__native_word(t) || sizeof(t) == sizeof(__dword_type), \
 		"Unsupported access size for {READ,WRITE}_ONCE().")
 
 /*
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 1a957ea2f4fe..54b56ae25db7 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -469,6 +469,12 @@ struct ftrace_likely_data {
 		unsigned type:	(unsigned type)0,			\
 		signed type:	(signed type)0
 
+#ifdef __SIZEOF_INT128__
+#define __dword_type __int128
+#else
+#define __dword_type long long
+#endif
+
 #define __unqual_scalar_typeof(x) typeof(				\
 		_Generic((x),						\
 			 char:	(char)0,				\
@@ -476,7 +482,7 @@ struct ftrace_likely_data {
 			 __scalar_type_to_expr_cases(short),		\
 			 __scalar_type_to_expr_cases(int),		\
 			 __scalar_type_to_expr_cases(long),		\
-			 __scalar_type_to_expr_cases(long long),	\
+			 __scalar_type_to_expr_cases(__dword_type),	\
 			 default: (x)))
 
 /* Is this type a native word size -- useful for atomic operations */
-- 
2.34.1

[PATCH v7 04/10] iommu/amd: Introduce struct ivhd_dte_flags to store persistent DTE flags

[Suravee Suthikulpanit]

During early initialization, the driver parses IVRS IVHD block to get list
of downstream devices along with their DTE flags (i.e INITPass, EIntPass,
NMIPass, SysMgt, Lint0Pass, Lint1Pass). This information is currently
store in the device DTE, and needs to be preserved when clearing
and configuring each DTE, which makes it difficult to manage.

Introduce struct ivhd_dte_flags to store IVHD DTE settings for a device or
range of devices, which are stored in the amd_ivhd_dev_flags_list during
initial IVHD parsing.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu_types.h |  15 ++++
 drivers/iommu/amd/init.c            | 110 ++++++++++++++++++++--------
 2 files changed, 96 insertions(+), 29 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index dadc65808951..7e055a226794 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -220,6 +220,8 @@
 #define DEV_ENTRY_EX            0x67
 #define DEV_ENTRY_SYSMGT1       0x68
 #define DEV_ENTRY_SYSMGT2       0x69
+#define DTE_DATA1_SYSMGT_MASK	GENMASK_ULL(41, 40)
+
 #define DEV_ENTRY_IRQ_TBL_EN	0x80
 #define DEV_ENTRY_INIT_PASS     0xb8
 #define DEV_ENTRY_EINT_PASS     0xb9
@@ -516,6 +518,9 @@ extern struct kmem_cache *amd_iommu_irq_cache;
 #define for_each_pdom_dev_data_safe(pdom_dev_data, next, pdom) \
 	list_for_each_entry_safe((pdom_dev_data), (next), &pdom->dev_data_list, list)
 
+#define for_each_ivhd_dte_flags(entry) \
+	list_for_each_entry((entry), &amd_ivhd_dev_flags_list, list)
+
 struct amd_iommu;
 struct iommu_domain;
 struct irq_domain;
@@ -885,6 +890,16 @@ struct dev_table_entry {
 	u64 data[4];
 };
 
+/*
+ * Structure to sture persistent DTE flags from IVHD
+ */
+struct ivhd_dte_flags {
+	struct list_head list;
+	u16 devid_first;
+	u16 devid_last;
+	struct dev_table_entry dte;
+};
+
 /*
  * One entry for unity mappings parsed out of the ACPI table.
  */
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 8868838139df..98b4b116d557 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -174,8 +174,8 @@ bool amd_iommu_snp_en;
 EXPORT_SYMBOL(amd_iommu_snp_en);
 
 LIST_HEAD(amd_iommu_pci_seg_list);	/* list of all PCI segments */
-LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
-					   system */
+LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the system */
+LIST_HEAD(amd_ivhd_dev_flags_list);	/* list of all IVHD device entry settings */
 
 /* Array to assign indices to IOMMUs*/
 struct amd_iommu *amd_iommus[MAX_IOMMUS];
@@ -993,6 +993,14 @@ static void iommu_enable_gt(struct amd_iommu *iommu)
 }
 
 /* sets a specific bit in the device table entry. */
+static void set_dte_bit(struct dev_table_entry *dte, u8 bit)
+{
+	int i = (bit >> 6) & 0x03;
+	int _bit = bit & 0x3f;
+
+	dte->data[i] |= (1UL << _bit);
+}
+
 static void __set_dev_entry_bit(struct dev_table_entry *dev_table,
 				u16 devid, u8 bit)
 {
@@ -1140,6 +1148,17 @@ static bool copy_device_table(void)
 	return true;
 }
 
+static bool search_ivhd_dte_flags(u16 first, u16 last)
+{
+	struct ivhd_dte_flags *e;
+
+	for_each_ivhd_dte_flags(e) {
+		if ((e->devid_first == first) && (e->devid_last == last))
+			return true;
+	}
+	return false;
+}
+
 void amd_iommu_apply_erratum_63(struct amd_iommu *iommu, u16 devid)
 {
 	int sysmgt;
@@ -1155,27 +1174,65 @@ void amd_iommu_apply_erratum_63(struct amd_iommu *iommu, u16 devid)
  * This function takes the device specific flags read from the ACPI
  * table and sets up the device table entry with that information
  */
-static void __init set_dev_entry_from_acpi(struct amd_iommu *iommu,
-					   u16 devid, u32 flags, u32 ext_flags)
+static void __init
+set_dev_entry_from_acpi_range(struct amd_iommu *iommu, u16 first, u16 last,
+			      u32 flags, u32 ext_flags)
 {
-	if (flags & ACPI_DEVFLAG_INITPASS)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_INIT_PASS);
-	if (flags & ACPI_DEVFLAG_EXTINT)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_EINT_PASS);
-	if (flags & ACPI_DEVFLAG_NMI)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_NMI_PASS);
-	if (flags & ACPI_DEVFLAG_SYSMGT1)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_SYSMGT1);
-	if (flags & ACPI_DEVFLAG_SYSMGT2)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_SYSMGT2);
-	if (flags & ACPI_DEVFLAG_LINT0)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_LINT0_PASS);
-	if (flags & ACPI_DEVFLAG_LINT1)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_LINT1_PASS);
+	int i;
+	struct dev_table_entry dte = {};
+
+	/* Parse IVHD DTE setting flags and store information */
+	if (flags) {
+		struct ivhd_dte_flags *d;
 
-	amd_iommu_apply_erratum_63(iommu, devid);
+		if (search_ivhd_dte_flags(first, last))
+			return;
 
-	amd_iommu_set_rlookup_table(iommu, devid);
+		d = kzalloc(sizeof(struct ivhd_dte_flags), GFP_KERNEL);
+		if (!d)
+			return;
+
+		pr_debug("%s: devid range %#x:%#x\n", __func__, first, last);
+
+		if (flags & ACPI_DEVFLAG_INITPASS)
+			set_dte_bit(&dte, DEV_ENTRY_INIT_PASS);
+		if (flags & ACPI_DEVFLAG_EXTINT)
+			set_dte_bit(&dte, DEV_ENTRY_EINT_PASS);
+		if (flags & ACPI_DEVFLAG_NMI)
+			set_dte_bit(&dte, DEV_ENTRY_NMI_PASS);
+		if (flags & ACPI_DEVFLAG_SYSMGT1)
+			set_dte_bit(&dte, DEV_ENTRY_SYSMGT1);
+		if (flags & ACPI_DEVFLAG_SYSMGT2)
+			set_dte_bit(&dte, DEV_ENTRY_SYSMGT2);
+		if (flags & ACPI_DEVFLAG_LINT0)
+			set_dte_bit(&dte, DEV_ENTRY_LINT0_PASS);
+		if (flags & ACPI_DEVFLAG_LINT1)
+			set_dte_bit(&dte, DEV_ENTRY_LINT1_PASS);
+
+		/* Apply erratum 63, which needs info in initial_dte */
+		if (FIELD_GET(DTE_DATA1_SYSMGT_MASK, dte.data[1]) == 0x1)
+			dte.data[0] |= DTE_FLAG_IW;
+
+		memcpy(&d->dte, &dte, sizeof(dte));
+		d->devid_first = first;
+		d->devid_last = last;
+		list_add_tail(&d->list, &amd_ivhd_dev_flags_list);
+	}
+
+	for (i = first; i <= last; i++)  {
+		if (flags) {
+			struct dev_table_entry *dev_table = get_dev_table(iommu);
+
+			memcpy(&dev_table[i], &dte, sizeof(dte));
+		}
+		amd_iommu_set_rlookup_table(iommu, i);
+	}
+}
+
+static void __init set_dev_entry_from_acpi(struct amd_iommu *iommu,
+					   u16 devid, u32 flags, u32 ext_flags)
+{
+	set_dev_entry_from_acpi_range(iommu, devid, devid, flags, ext_flags);
 }
 
 int __init add_special_device(u8 type, u8 id, u32 *devid, bool cmd_line)
@@ -1336,9 +1393,7 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 		case IVHD_DEV_ALL:
 
 			DUMP_printk("  DEV_ALL\t\t\tsetting: %#02x\n", e->flags);
-
-			for (dev_i = 0; dev_i <= pci_seg->last_bdf; ++dev_i)
-				set_dev_entry_from_acpi(iommu, dev_i, e->flags, 0);
+			set_dev_entry_from_acpi_range(iommu, 0, pci_seg->last_bdf, e->flags, 0);
 			break;
 		case IVHD_DEV_SELECT:
 
@@ -1432,14 +1487,11 @@ static int __init init_iommu_from_acpi(struct amd_iommu *iommu,
 
 			devid = e->devid;
 			for (dev_i = devid_start; dev_i <= devid; ++dev_i) {
-				if (alias) {
+				if (alias)
 					pci_seg->alias_table[dev_i] = devid_to;
-					set_dev_entry_from_acpi(iommu,
-						devid_to, flags, ext_flags);
-				}
-				set_dev_entry_from_acpi(iommu, dev_i,
-							flags, ext_flags);
 			}
+			set_dev_entry_from_acpi_range(iommu, devid_start, devid, flags, ext_flags);
+			set_dev_entry_from_acpi(iommu, devid_to, flags, ext_flags);
 			break;
 		case IVHD_DEV_SPECIAL: {
 			u8 handle, type;
-- 
2.34.1

[PATCH v7 05/10] iommu/amd: Introduce helper function to update 256-bit DTE

[Suravee Suthikulpanit]

The current implementation does not follow 128-bit write requirement
to update DTE as specified in the AMD I/O Virtualization Techonology
(IOMMU) Specification.

Therefore, modify the struct dev_table_entry to contain union of u128 data
array, and introduce a helper functions update_dte256() to update DTE using
two 128-bit cmpxchg operations to update 256-bit DTE with the modified
structure, and take into account the DTE[V, GV] bits when programming
the DTE to ensure proper order of DTE programming and flushing.

In addition, introduce a per-DTE spin_lock struct dev_data.dte_lock to
provide synchronization when updating the DTE to prevent cmpxchg128
failure.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu_types.h |  10 ++-
 drivers/iommu/amd/iommu.c           | 116 ++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 7e055a226794..e11a77c0f592 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -427,9 +427,13 @@
 #define DTE_GCR3_SHIFT_C	43
 
 #define DTE_GPT_LEVEL_SHIFT	54
+#define DTE_GPT_LEVEL_MASK	GENMASK_ULL(55, 54)
 
 #define GCR3_VALID		0x01ULL
 
+/* DTE[128:179] | DTE[184:191] */
+#define DTE_DATA2_INTR_MASK	~GENMASK_ULL(55, 52)
+
 #define IOMMU_PAGE_MASK (((1ULL << 52) - 1) & ~0xfffULL)
 #define IOMMU_PTE_PRESENT(pte) ((pte) & IOMMU_PTE_PR)
 #define IOMMU_PTE_DIRTY(pte) ((pte) & IOMMU_PTE_HD)
@@ -837,6 +841,7 @@ struct devid_map {
 struct iommu_dev_data {
 	/*Protect against attach/detach races */
 	spinlock_t lock;
+	spinlock_t dte_lock;              /* DTE lock for 256-bit access */
 
 	struct list_head list;		  /* For domain->dev_list */
 	struct llist_node dev_data_list;  /* For global dev_data_list */
@@ -887,7 +892,10 @@ extern struct amd_iommu *amd_iommus[MAX_IOMMUS];
  * Structure defining one entry in the device table
  */
 struct dev_table_entry {
-	u64 data[4];
+	union {
+		u64 data[4];
+		u128 data128[2];
+	};
 };
 
 /*
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 8364cd6fa47d..eb22ed1a219c 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -77,12 +77,118 @@ static void detach_device(struct device *dev);
 static void set_dte_entry(struct amd_iommu *iommu,
 			  struct iommu_dev_data *dev_data);
 
+static void iommu_flush_dte_sync(struct amd_iommu *iommu, u16 devid);
+
 /****************************************************************************
  *
  * Helper functions
  *
  ****************************************************************************/
 
+static void write_dte_upper128(struct dev_table_entry *ptr, struct dev_table_entry *new)
+{
+	struct dev_table_entry old = {};
+
+	old.data128[1] = READ_ONCE(ptr->data128[1]);
+	do {
+		/*
+		 * Preserve DTE_DATA2_INTR_MASK. This needs to be
+		 * done here since it requires to be inside
+		 * spin_lock(&dev_data->dte_lock) context.
+		 */
+		new->data[2] &= ~DTE_DATA2_INTR_MASK;
+		new->data[2] |= old.data[2] & DTE_DATA2_INTR_MASK;
+
+	/* Note: try_cmpxchg inherently update &old.data128[1] on failure */
+	} while (!try_cmpxchg128(&ptr->data128[1], &old.data128[1], new->data128[1]));
+}
+
+static void write_dte_lower128(struct dev_table_entry *ptr, struct dev_table_entry *new)
+{
+	struct dev_table_entry old = {};
+
+	old.data128[0] = READ_ONCE(ptr->data128[0]);
+	do {
+	/* Note: try_cmpxchg inherently update &old.data128[0] on failure */
+	} while (!try_cmpxchg128(&ptr->data128[0], &old.data128[0], new->data128[0]));
+}
+
+/*
+ * Note:
+ * IOMMU reads the entire Device Table entry in a single 256-bit transaction
+ * but the driver is programming DTE using 2 128-bit cmpxchg. So, the driver
+ * need to ensure the following:
+ *   - DTE[V|GV] bit is being written last when setting.
+ *   - DTE[V|GV] bit is being written first when clearing.
+ *
+ * This function is used only by code, which updates DMA translation part of the DTE.
+ * So, only consider control bits related to DMA when updating the entry.
+ */
+static void update_dte256(struct amd_iommu *iommu, struct iommu_dev_data *dev_data,
+			  struct dev_table_entry *new)
+{
+	struct dev_table_entry *dev_table = get_dev_table(iommu);
+	struct dev_table_entry *ptr = &dev_table[dev_data->devid];
+
+	spin_lock(&dev_data->dte_lock);
+
+	if (!(ptr->data[0] & DTE_FLAG_V)) {
+		/* Existing DTE is not valid. */
+		write_dte_upper128(ptr, new);
+		write_dte_lower128(ptr, new);
+		iommu_flush_dte_sync(iommu, dev_data->devid);
+	} else if (!(new->data[0] & DTE_FLAG_V)) {
+		/* Existing DTE is valid. New DTE is not valid.  */
+		write_dte_lower128(ptr, new);
+		write_dte_upper128(ptr, new);
+		iommu_flush_dte_sync(iommu, dev_data->devid);
+	} else if (!FIELD_GET(DTE_FLAG_GV, ptr->data[0])) {
+		/*
+		 * Both DTEs are valid.
+		 * Existing DTE has no guest page table.
+		 */
+		write_dte_upper128(ptr, new);
+		write_dte_lower128(ptr, new);
+		iommu_flush_dte_sync(iommu, dev_data->devid);
+	} else if (!FIELD_GET(DTE_FLAG_GV, new->data[0])) {
+		/*
+		 * Both DTEs are valid.
+		 * Existing DTE has guest page table,
+		 * new DTE has no guest page table,
+		 */
+		write_dte_lower128(ptr, new);
+		write_dte_upper128(ptr, new);
+		iommu_flush_dte_sync(iommu, dev_data->devid);
+	} else if (FIELD_GET(DTE_GPT_LEVEL_MASK, ptr->data[2]) !=
+		   FIELD_GET(DTE_GPT_LEVEL_MASK, new->data[2])) {
+		/*
+		 * Both DTEs are valid and have guest page table,
+		 * but have different number of levels. So, we need
+		 * to upadte both upper and lower 128-bit value, which
+		 * require disabling and flushing.
+		 */
+		struct dev_table_entry clear = {};
+
+		/* First disable DTE */
+		write_dte_lower128(ptr, &clear);
+		iommu_flush_dte_sync(iommu, dev_data->devid);
+
+		/* Then update DTE */
+		write_dte_upper128(ptr, new);
+		write_dte_lower128(ptr, new);
+		iommu_flush_dte_sync(iommu, dev_data->devid);
+	} else {
+		/*
+		 * Both DTEs are valid and have guest page table,
+		 * and same number of levels. We just need to only
+		 * update the lower 128-bit. So no need to disable DTE.
+		 */
+		write_dte_lower128(ptr, new);
+	}
+
+	spin_unlock(&dev_data->dte_lock);
+}
+
 static inline bool pdom_is_v2_pgtbl_mode(struct protection_domain *pdom)
 {
 	return (pdom && (pdom->pd_mode == PD_MODE_V2));
@@ -203,6 +309,7 @@ static struct iommu_dev_data *alloc_dev_data(struct amd_iommu *iommu, u16 devid)
 		return NULL;
 
 	spin_lock_init(&dev_data->lock);
+	spin_lock_init(&dev_data->dte_lock);
 	dev_data->devid = devid;
 	ratelimit_default_init(&dev_data->rs);
 
@@ -1272,6 +1379,15 @@ static int iommu_flush_dte(struct amd_iommu *iommu, u16 devid)
 	return iommu_queue_command(iommu, &cmd);
 }
 
+static void iommu_flush_dte_sync(struct amd_iommu *iommu, u16 devid)
+{
+	int ret;
+
+	ret = iommu_flush_dte(iommu, devid);
+	if (!ret)
+		iommu_completion_wait(iommu);
+}
+
 static void amd_iommu_flush_dte_all(struct amd_iommu *iommu)
 {
 	u32 devid;
-- 
2.34.1

[PATCH v7 06/10] iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers

[Suravee Suthikulpanit]

Also, the set_dte_entry() is used to program several DTE fields (e.g.
stage1 table, stage2 table, domain id, and etc.), which is difficult
to keep track with current implementation.

Therefore, separate logic for clearing DTE (i.e. make_clear_dte) and
another function for setting up the GCR3 Table Root Pointer, GIOV, GV,
GLX, and GuestPagingMode into another function set_dte_gcr3_table().

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu.h       |   2 +
 drivers/iommu/amd/amd_iommu_types.h |  13 +--
 drivers/iommu/amd/init.c            |  28 +++++-
 drivers/iommu/amd/iommu.c           | 129 ++++++++++++++++------------
 4 files changed, 104 insertions(+), 68 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 6386fa4556d9..35d1e40930a5 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -177,3 +177,5 @@ void amd_iommu_domain_set_pgtable(struct protection_domain *domain,
 struct dev_table_entry *get_dev_table(struct amd_iommu *iommu);
 
 #endif
+
+struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 devid);
diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index e11a77c0f592..561972356ff6 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -409,8 +409,7 @@
 #define DTE_FLAG_HAD	(3ULL << 7)
 #define DTE_FLAG_GIOV	BIT_ULL(54)
 #define DTE_FLAG_GV	BIT_ULL(55)
-#define DTE_GLX_SHIFT	(56)
-#define DTE_GLX_MASK	(3)
+#define DTE_GLX		GENMASK_ULL(57, 56)
 #define DTE_FLAG_IR	BIT_ULL(61)
 #define DTE_FLAG_IW	BIT_ULL(62)
 
@@ -418,13 +417,9 @@
 #define DTE_FLAG_MASK	(0x3ffULL << 32)
 #define DEV_DOMID_MASK	0xffffULL
 
-#define DTE_GCR3_VAL_A(x)	(((x) >> 12) & 0x00007ULL)
-#define DTE_GCR3_VAL_B(x)	(((x) >> 15) & 0x0ffffULL)
-#define DTE_GCR3_VAL_C(x)	(((x) >> 31) & 0x1fffffULL)
-
-#define DTE_GCR3_SHIFT_A	58
-#define DTE_GCR3_SHIFT_B	16
-#define DTE_GCR3_SHIFT_C	43
+#define DTE_GCR3_14_12	GENMASK_ULL(60, 58)
+#define DTE_GCR3_30_15	GENMASK_ULL(31, 16)
+#define DTE_GCR3_51_31	GENMASK_ULL(63, 43)
 
 #define DTE_GPT_LEVEL_SHIFT	54
 #define DTE_GPT_LEVEL_MASK	GENMASK_ULL(55, 54)
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 98b4b116d557..9f5bda23e45e 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -1093,11 +1093,9 @@ static bool __copy_device_table(struct amd_iommu *iommu)
 			__set_bit(dom_id, amd_iommu_pd_alloc_bitmap);
 			/* If gcr3 table existed, mask it out */
 			if (old_devtb[devid].data[0] & DTE_FLAG_GV) {
-				tmp = DTE_GCR3_VAL_B(~0ULL) << DTE_GCR3_SHIFT_B;
-				tmp |= DTE_GCR3_VAL_C(~0ULL) << DTE_GCR3_SHIFT_C;
+				tmp = (DTE_GCR3_30_15 | DTE_GCR3_51_31);
 				pci_seg->old_dev_tbl_cpy[devid].data[1] &= ~tmp;
-				tmp = DTE_GCR3_VAL_A(~0ULL) << DTE_GCR3_SHIFT_A;
-				tmp |= DTE_FLAG_GV;
+				tmp = (DTE_GCR3_14_12 | DTE_FLAG_GV);
 				pci_seg->old_dev_tbl_cpy[devid].data[0] &= ~tmp;
 			}
 		}
@@ -1148,6 +1146,28 @@ static bool copy_device_table(void)
 	return true;
 }
 
+struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 devid)
+{
+	u16 f = 0, l = 0xFFFF;
+	struct ivhd_dte_flags *e;
+	struct dev_table_entry *dte = NULL;
+
+	for_each_ivhd_dte_flags(e) {
+		/*
+		 * Need to go through the whole list to find the smallest range,
+		 * which contains the devid. Then store it in f and l variables.
+		 */
+		if ((e->devid_first >= devid) && (e->devid_last <= devid)) {
+			if (f < e->devid_first)
+				f = e->devid_first;
+			if (e->devid_last < l)
+				l = e->devid_last;
+			dte = &(e->dte);
+		}
+	}
+	return dte;
+}
+
 static bool search_ivhd_dte_flags(u16 first, u16 last)
 {
 	struct ivhd_dte_flags *e;
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index eb22ed1a219c..fd239b38809b 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1958,90 +1958,109 @@ int amd_iommu_clear_gcr3(struct iommu_dev_data *dev_data, ioasid_t pasid)
 	return ret;
 }
 
+static void make_clear_dte(struct iommu_dev_data *dev_data, struct dev_table_entry *ptr,
+			   struct dev_table_entry *new)
+{
+	/* All existing DTE must have V bit set */
+	new->data128[0] = DTE_FLAG_V;
+	new->data128[1] = 0;
+}
+
+/*
+ * Note:
+ * The old value for GCR3 table and GPT have been cleared from caller.
+ */
+static void set_dte_gcr3_table(struct amd_iommu *iommu,
+			       struct iommu_dev_data *dev_data,
+			       struct dev_table_entry *target)
+{
+	struct gcr3_tbl_info *gcr3_info = &dev_data->gcr3_info;
+	u64 gcr3;
+
+	if (!gcr3_info->gcr3_tbl)
+		return;
+
+	pr_debug("%s: devid=%#x, glx=%#x, gcr3_tbl=%#llx\n",
+		 __func__, dev_data->devid, gcr3_info->glx,
+		 (unsigned long long)gcr3_info->gcr3_tbl);
+
+	gcr3 = iommu_virt_to_phys(gcr3_info->gcr3_tbl);
+
+	target->data[0] |= DTE_FLAG_GV |
+			   FIELD_PREP(DTE_GLX, gcr3_info->glx) |
+			   FIELD_PREP(DTE_GCR3_14_12, gcr3 >> 12);
+	if (pdom_is_v2_pgtbl_mode(dev_data->domain))
+		target->data[0] |= DTE_FLAG_GIOV;
+
+	target->data[1] |= FIELD_PREP(DTE_GCR3_30_15, gcr3 >> 15) |
+			   FIELD_PREP(DTE_GCR3_51_31, gcr3 >> 31);
+
+	/* Guest page table can only support 4 and 5 levels  */
+	if (amd_iommu_gpt_level == PAGE_MODE_5_LEVEL)
+		target->data[2] |= FIELD_PREP(DTE_GPT_LEVEL_MASK, GUEST_PGTABLE_5_LEVEL);
+	else
+		target->data[2] |= FIELD_PREP(DTE_GPT_LEVEL_MASK, GUEST_PGTABLE_4_LEVEL);
+}
+
 static void set_dte_entry(struct amd_iommu *iommu,
 			  struct iommu_dev_data *dev_data)
 {
-	u64 pte_root = 0;
-	u64 flags = 0;
-	u32 old_domid;
-	u16 devid = dev_data->devid;
 	u16 domid;
+	u32 old_domid;
+	struct dev_table_entry *initial_dte;
+	struct dev_table_entry new = {};
 	struct protection_domain *domain = dev_data->domain;
-	struct dev_table_entry *dev_table = get_dev_table(iommu);
 	struct gcr3_tbl_info *gcr3_info = &dev_data->gcr3_info;
+	struct dev_table_entry *dte = &get_dev_table(iommu)[dev_data->devid];
 
 	if (gcr3_info && gcr3_info->gcr3_tbl)
 		domid = dev_data->gcr3_info.domid;
 	else
 		domid = domain->id;
 
+	make_clear_dte(dev_data, dte, &new);
+
 	if (domain->iop.mode != PAGE_MODE_NONE)
-		pte_root = iommu_virt_to_phys(domain->iop.root);
+		new.data[0] = iommu_virt_to_phys(domain->iop.root);
 
-	pte_root |= (domain->iop.mode & DEV_ENTRY_MODE_MASK)
+	new.data[0] |= (domain->iop.mode & DEV_ENTRY_MODE_MASK)
 		    << DEV_ENTRY_MODE_SHIFT;
 
-	pte_root |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V;
+	new.data[0] |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V;
 
 	/*
-	 * When SNP is enabled, Only set TV bit when IOMMU
-	 * page translation is in use.
+	 * When SNP is enabled, we can only support TV=1 with non-zero domain ID.
+	 * This is prevented by the SNP-enable and IOMMU_DOMAIN_IDENTITY check in
+	 * do_iommu_domain_alloc().
 	 */
-	if (!amd_iommu_snp_en || (domid != 0))
-		pte_root |= DTE_FLAG_TV;
-
-	flags = dev_table[devid].data[1];
-
-	if (dev_data->ats_enabled)
-		flags |= DTE_FLAG_IOTLB;
+	WARN_ON(amd_iommu_snp_en && (domid == 0));
+	new.data[0] |= DTE_FLAG_TV;
 
 	if (dev_data->ppr)
-		pte_root |= 1ULL << DEV_ENTRY_PPR;
+		new.data[0] |= 1ULL << DEV_ENTRY_PPR;
 
 	if (domain->dirty_tracking)
-		pte_root |= DTE_FLAG_HAD;
-
-	if (gcr3_info && gcr3_info->gcr3_tbl) {
-		u64 gcr3 = iommu_virt_to_phys(gcr3_info->gcr3_tbl);
-		u64 glx  = gcr3_info->glx;
-		u64 tmp;
-
-		pte_root |= DTE_FLAG_GV;
-		pte_root |= (glx & DTE_GLX_MASK) << DTE_GLX_SHIFT;
+		new.data[0] |= DTE_FLAG_HAD;
 
-		/* First mask out possible old values for GCR3 table */
-		tmp = DTE_GCR3_VAL_B(~0ULL) << DTE_GCR3_SHIFT_B;
-		flags    &= ~tmp;
-
-		tmp = DTE_GCR3_VAL_C(~0ULL) << DTE_GCR3_SHIFT_C;
-		flags    &= ~tmp;
-
-		/* Encode GCR3 table into DTE */
-		tmp = DTE_GCR3_VAL_A(gcr3) << DTE_GCR3_SHIFT_A;
-		pte_root |= tmp;
-
-		tmp = DTE_GCR3_VAL_B(gcr3) << DTE_GCR3_SHIFT_B;
-		flags    |= tmp;
-
-		tmp = DTE_GCR3_VAL_C(gcr3) << DTE_GCR3_SHIFT_C;
-		flags    |= tmp;
+	if (dev_data->ats_enabled)
+		new.data[1] |= DTE_FLAG_IOTLB;
 
-		if (amd_iommu_gpt_level == PAGE_MODE_5_LEVEL) {
-			dev_table[devid].data[2] |=
-				((u64)GUEST_PGTABLE_5_LEVEL << DTE_GPT_LEVEL_SHIFT);
-		}
+	old_domid = READ_ONCE(dte->data[1]) & DEV_DOMID_MASK;
+	new.data[1] |= domid;
 
-		/* GIOV is supported with V2 page table mode only */
-		if (pdom_is_v2_pgtbl_mode(domain))
-			pte_root |= DTE_FLAG_GIOV;
+	/*
+	 * 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(dev_data->devid);
+	if (initial_dte) {
+		new.data128[0] |= initial_dte->data128[0];
+		new.data128[1] |= initial_dte->data128[1];
 	}
 
-	flags &= ~DEV_DOMID_MASK;
-	flags |= domid;
+	set_dte_gcr3_table(iommu, dev_data, &new);
 
-	old_domid = dev_table[devid].data[1] & DEV_DOMID_MASK;
-	dev_table[devid].data[1]  = flags;
-	dev_table[devid].data[0]  = pte_root;
+	update_dte256(iommu, dev_data, &new);
 
 	/*
 	 * A kdump kernel might be replacing a domain ID that was copied from
-- 
2.34.1

[PATCH v7 07/10] iommu/amd: Introduce helper function get_dte256()

[Suravee Suthikulpanit]

And use it in clone_alias() along with update_dte256().
Also use get_dte256() in dump_dte_entry().

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/iommu.c | 61 ++++++++++++++++++++++++++++++++-------
 1 file changed, 50 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index fd239b38809b..c8b0be83ee9b 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -79,6 +79,8 @@ static void set_dte_entry(struct amd_iommu *iommu,
 
 static void iommu_flush_dte_sync(struct amd_iommu *iommu, u16 devid);
 
+static struct iommu_dev_data *find_dev_data(struct amd_iommu *iommu, u16 devid);
+
 /****************************************************************************
  *
  * Helper functions
@@ -189,6 +191,20 @@ static void update_dte256(struct amd_iommu *iommu, struct iommu_dev_data *dev_da
 	spin_unlock(&dev_data->dte_lock);
 }
 
+static void get_dte256(struct amd_iommu *iommu, struct iommu_dev_data *dev_data,
+		      struct dev_table_entry *dte)
+{
+	struct dev_table_entry *ptr;
+	struct dev_table_entry *dev_table = get_dev_table(iommu);
+
+	ptr = &dev_table[dev_data->devid];
+
+	spin_lock(&dev_data->dte_lock);
+	dte->data128[0] = READ_ONCE(ptr->data128[0]);
+	dte->data128[1] = READ_ONCE(ptr->data128[1]);
+	spin_unlock(&dev_data->dte_lock);
+}
+
 static inline bool pdom_is_v2_pgtbl_mode(struct protection_domain *pdom)
 {
 	return (pdom && (pdom->pd_mode == PD_MODE_V2));
@@ -337,9 +353,11 @@ static struct iommu_dev_data *search_dev_data(struct amd_iommu *iommu, u16 devid
 
 static int clone_alias(struct pci_dev *pdev, u16 alias, void *data)
 {
+	struct dev_table_entry new;
 	struct amd_iommu *iommu;
-	struct dev_table_entry *dev_table;
+	struct iommu_dev_data *dev_data, *alias_data;
 	u16 devid = pci_dev_id(pdev);
+	int ret = 0;
 
 	if (devid == alias)
 		return 0;
@@ -348,13 +366,27 @@ static int clone_alias(struct pci_dev *pdev, u16 alias, void *data)
 	if (!iommu)
 		return 0;
 
-	amd_iommu_set_rlookup_table(iommu, alias);
-	dev_table = get_dev_table(iommu);
-	memcpy(dev_table[alias].data,
-	       dev_table[devid].data,
-	       sizeof(dev_table[alias].data));
+	/* Copy the data from pdev */
+	dev_data = dev_iommu_priv_get(&pdev->dev);
+	if (!dev_data) {
+		pr_err("%s : Failed to get dev_data for 0x%x\n", __func__, devid);
+		ret = -EINVAL;
+		goto out;
+	}
+	get_dte256(iommu, dev_data, &new);
 
-	return 0;
+	/* Setup alias */
+	alias_data = find_dev_data(iommu, alias);
+	if (!alias_data) {
+		pr_err("%s : Failed to get alias dev_data for 0x%x\n", __func__, alias);
+		ret = -EINVAL;
+		goto out;
+	}
+	update_dte256(iommu, alias_data, &new);
+
+	amd_iommu_set_rlookup_table(iommu, alias);
+out:
+	return ret;
 }
 
 static void clone_aliases(struct amd_iommu *iommu, struct device *dev)
@@ -627,6 +659,12 @@ static int iommu_init_device(struct amd_iommu *iommu, struct device *dev)
 		return -ENOMEM;
 
 	dev_data->dev = dev;
+
+	/*
+	 * The dev_iommu_priv_set() needes to be called before setup_aliases.
+	 * Otherwise, subsequent call to dev_iommu_priv_get() will fail.
+	 */
+	dev_iommu_priv_set(dev, dev_data);
 	setup_aliases(iommu, dev);
 
 	/*
@@ -640,8 +678,6 @@ static int iommu_init_device(struct amd_iommu *iommu, struct device *dev)
 		dev_data->flags = pdev_get_caps(to_pci_dev(dev));
 	}
 
-	dev_iommu_priv_set(dev, dev_data);
-
 	return 0;
 }
 
@@ -688,10 +724,13 @@ static void amd_iommu_uninit_device(struct device *dev)
 static void dump_dte_entry(struct amd_iommu *iommu, u16 devid)
 {
 	int i;
-	struct dev_table_entry *dev_table = get_dev_table(iommu);
+	struct dev_table_entry dte;
+	struct iommu_dev_data *dev_data = find_dev_data(iommu, devid);
+
+	get_dte256(iommu, dev_data, &dte);
 
 	for (i = 0; i < 4; ++i)
-		pr_err("DTE[%d]: %016llx\n", i, dev_table[devid].data[i]);
+		pr_err("DTE[%d]: %016llx\n", i, dte.data[i]);
 }
 
 static void dump_command(unsigned long phys_addr)
-- 
2.34.1

[PATCH v7 08/10] iommu/amd: Modify clear_dte_entry() to avoid in-place update

[Suravee Suthikulpanit]

By reusing the make_clear_dte() and update_dte256().

Also, there is no need to set TV bit for non-SNP system when clearing DTE
for blocked domain, and no longer need to apply erratum 63 in clear_dte()
since it is already stored in struct ivhd_dte_flags and apply in
set_dte_entry().

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/iommu.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index c8b0be83ee9b..b71fb22d001a 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2111,19 +2111,16 @@ static void set_dte_entry(struct amd_iommu *iommu,
 	}
 }
 
-static void clear_dte_entry(struct amd_iommu *iommu, u16 devid)
+/*
+ * Clear DMA-remap related flags to block all DMA (blockeded domain)
+ */
+static void clear_dte_entry(struct amd_iommu *iommu, struct iommu_dev_data *dev_data)
 {
-	struct dev_table_entry *dev_table = get_dev_table(iommu);
-
-	/* remove entry from the device table seen by the hardware */
-	dev_table[devid].data[0]  = DTE_FLAG_V;
-
-	if (!amd_iommu_snp_en)
-		dev_table[devid].data[0] |= DTE_FLAG_TV;
-
-	dev_table[devid].data[1] &= DTE_FLAG_MASK;
+	struct dev_table_entry new = {};
+	struct dev_table_entry *dte = &get_dev_table(iommu)[dev_data->devid];
 
-	amd_iommu_apply_erratum_63(iommu, devid);
+	make_clear_dte(dev_data, dte, &new);
+	update_dte256(iommu, dev_data, &new);
 }
 
 /* Update and flush DTE for the given device */
@@ -2134,7 +2131,7 @@ static void dev_update_dte(struct iommu_dev_data *dev_data, bool set)
 	if (set)
 		set_dte_entry(iommu, dev_data);
 	else
-		clear_dte_entry(iommu, dev_data->devid);
+		clear_dte_entry(iommu, dev_data);
 
 	clone_aliases(iommu, dev_data->dev);
 	device_flush_dte(dev_data);
-- 
2.34.1

[PATCH v7 09/10] iommu/amd: Lock DTE before updating the entry with WRITE_ONCE()

[Suravee Suthikulpanit]

When updating only within a 64-bit tuple of a DTE, just lock the DTE and
use WRITE_ONCE() because it is writing to memory read back by HW.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu.h |  1 +
 drivers/iommu/amd/iommu.c     | 43 +++++++++++++++++++----------------
 2 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 35d1e40930a5..bfc61f7ed923 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -179,3 +179,4 @@ struct dev_table_entry *get_dev_table(struct amd_iommu *iommu);
 #endif
 
 struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 devid);
+struct iommu_dev_data *search_dev_data(struct amd_iommu *iommu, u16 devid);
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index b71fb22d001a..9459695bdc12 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -333,7 +333,7 @@ static struct iommu_dev_data *alloc_dev_data(struct amd_iommu *iommu, u16 devid)
 	return dev_data;
 }
 
-static struct iommu_dev_data *search_dev_data(struct amd_iommu *iommu, u16 devid)
+struct iommu_dev_data *search_dev_data(struct amd_iommu *iommu, u16 devid)
 {
 	struct iommu_dev_data *dev_data;
 	struct llist_node *node;
@@ -2791,12 +2791,12 @@ static int amd_iommu_set_dirty_tracking(struct iommu_domain *domain,
 					bool enable)
 {
 	struct protection_domain *pdomain = to_pdomain(domain);
-	struct dev_table_entry *dev_table;
+	struct dev_table_entry *dte;
 	struct iommu_dev_data *dev_data;
 	bool domain_flush = false;
 	struct amd_iommu *iommu;
 	unsigned long flags;
-	u64 pte_root;
+	u64 new;
 
 	spin_lock_irqsave(&pdomain->lock, flags);
 	if (!(pdomain->dirty_tracking ^ enable)) {
@@ -2805,16 +2805,15 @@ static int amd_iommu_set_dirty_tracking(struct iommu_domain *domain,
 	}
 
 	list_for_each_entry(dev_data, &pdomain->dev_list, list) {
+		spin_lock(&dev_data->dte_lock);
 		iommu = get_amd_iommu_from_dev_data(dev_data);
-
-		dev_table = get_dev_table(iommu);
-		pte_root = dev_table[dev_data->devid].data[0];
-
-		pte_root = (enable ? pte_root | DTE_FLAG_HAD :
-				     pte_root & ~DTE_FLAG_HAD);
+		dte = &get_dev_table(iommu)[dev_data->devid];
+		new = READ_ONCE(dte->data[0]);
+		new = (enable ? new | DTE_FLAG_HAD : new & ~DTE_FLAG_HAD);
+		WRITE_ONCE(dte->data[0], new);
+		spin_unlock(&dev_data->dte_lock);
 
 		/* Flush device DTE */
-		dev_table[dev_data->devid].data[0] = pte_root;
 		device_flush_dte(dev_data);
 		domain_flush = true;
 	}
@@ -3079,17 +3078,23 @@ static void iommu_flush_irt_and_complete(struct amd_iommu *iommu, u16 devid)
 static void set_dte_irq_entry(struct amd_iommu *iommu, u16 devid,
 			      struct irq_remap_table *table)
 {
-	u64 dte;
-	struct dev_table_entry *dev_table = get_dev_table(iommu);
+	u64 new;
+	struct dev_table_entry *dte = &get_dev_table(iommu)[devid];
+	struct iommu_dev_data *dev_data = search_dev_data(iommu, devid);
+
+	if (dev_data)
+		spin_lock(&dev_data->dte_lock);
 
-	dte	= dev_table[devid].data[2];
-	dte	&= ~DTE_IRQ_PHYS_ADDR_MASK;
-	dte	|= iommu_virt_to_phys(table->table);
-	dte	|= DTE_IRQ_REMAP_INTCTL;
-	dte	|= DTE_INTTABLEN;
-	dte	|= DTE_IRQ_REMAP_ENABLE;
+	new = READ_ONCE(dte->data[2]);
+	new &= ~DTE_IRQ_PHYS_ADDR_MASK;
+	new |= iommu_virt_to_phys(table->table);
+	new |= DTE_IRQ_REMAP_INTCTL;
+	new |= DTE_INTTABLEN;
+	new |= DTE_IRQ_REMAP_ENABLE;
+	WRITE_ONCE(dte->data[2], new);
 
-	dev_table[devid].data[2] = dte;
+	if (dev_data)
+		spin_unlock(&dev_data->dte_lock);
 }
 
 static struct irq_remap_table *get_irq_table(struct amd_iommu *iommu, u16 devid)
-- 
2.34.1

[PATCH v7 10/10] iommu/amd: Remove amd_iommu_apply_erratum_63()

[Suravee Suthikulpanit]

Also replace __set_dev_entry_bit() with set_dte_bit() and remove unused
helper functions.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu.h |  1 -
 drivers/iommu/amd/init.c      | 50 +++--------------------------------
 2 files changed, 3 insertions(+), 48 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index bfc61f7ed923..7004274bcdda 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -16,7 +16,6 @@ irqreturn_t amd_iommu_int_thread_evtlog(int irq, void *data);
 irqreturn_t amd_iommu_int_thread_pprlog(int irq, void *data);
 irqreturn_t amd_iommu_int_thread_galog(int irq, void *data);
 irqreturn_t amd_iommu_int_handler(int irq, void *data);
-void amd_iommu_apply_erratum_63(struct amd_iommu *iommu, u16 devid);
 void amd_iommu_restart_log(struct amd_iommu *iommu, const char *evt_type,
 			   u8 cntrl_intr, u8 cntrl_log,
 			   u32 status_run_mask, u32 status_overflow_mask);
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 9f5bda23e45e..046628ba05a9 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -1001,38 +1001,6 @@ static void set_dte_bit(struct dev_table_entry *dte, u8 bit)
 	dte->data[i] |= (1UL << _bit);
 }
 
-static void __set_dev_entry_bit(struct dev_table_entry *dev_table,
-				u16 devid, u8 bit)
-{
-	int i = (bit >> 6) & 0x03;
-	int _bit = bit & 0x3f;
-
-	dev_table[devid].data[i] |= (1UL << _bit);
-}
-
-static void set_dev_entry_bit(struct amd_iommu *iommu, u16 devid, u8 bit)
-{
-	struct dev_table_entry *dev_table = get_dev_table(iommu);
-
-	return __set_dev_entry_bit(dev_table, devid, bit);
-}
-
-static int __get_dev_entry_bit(struct dev_table_entry *dev_table,
-			       u16 devid, u8 bit)
-{
-	int i = (bit >> 6) & 0x03;
-	int _bit = bit & 0x3f;
-
-	return (dev_table[devid].data[i] & (1UL << _bit)) >> _bit;
-}
-
-static int get_dev_entry_bit(struct amd_iommu *iommu, u16 devid, u8 bit)
-{
-	struct dev_table_entry *dev_table = get_dev_table(iommu);
-
-	return __get_dev_entry_bit(dev_table, devid, bit);
-}
-
 static bool __copy_device_table(struct amd_iommu *iommu)
 {
 	u64 int_ctl, int_tab_len, entry = 0;
@@ -1179,17 +1147,6 @@ static bool search_ivhd_dte_flags(u16 first, u16 last)
 	return false;
 }
 
-void amd_iommu_apply_erratum_63(struct amd_iommu *iommu, u16 devid)
-{
-	int sysmgt;
-
-	sysmgt = get_dev_entry_bit(iommu, devid, DEV_ENTRY_SYSMGT1) |
-		 (get_dev_entry_bit(iommu, devid, DEV_ENTRY_SYSMGT2) << 1);
-
-	if (sysmgt == 0x01)
-		set_dev_entry_bit(iommu, devid, DEV_ENTRY_IW);
-}
-
 /*
  * This function takes the device specific flags read from the ACPI
  * table and sets up the device table entry with that information
@@ -2644,9 +2601,9 @@ static void init_device_table_dma(struct amd_iommu_pci_seg *pci_seg)
 		return;
 
 	for (devid = 0; devid <= pci_seg->last_bdf; ++devid) {
-		__set_dev_entry_bit(dev_table, devid, DEV_ENTRY_VALID);
+		set_dte_bit(&dev_table[devid], DEV_ENTRY_VALID);
 		if (!amd_iommu_snp_en)
-			__set_dev_entry_bit(dev_table, devid, DEV_ENTRY_TRANSLATION);
+			set_dte_bit(&dev_table[devid], DEV_ENTRY_TRANSLATION);
 	}
 }
 
@@ -2674,8 +2631,7 @@ static void init_device_table(void)
 
 	for_each_pci_segment(pci_seg) {
 		for (devid = 0; devid <= pci_seg->last_bdf; ++devid)
-			__set_dev_entry_bit(pci_seg->dev_table,
-					    devid, DEV_ENTRY_IRQ_TBL_EN);
+			set_dte_bit(&pci_seg->dev_table[devid], DEV_ENTRY_IRQ_TBL_EN);
 	}
 }
 
-- 
2.34.1

Re: [PATCH v7 04/10] iommu/amd: Introduce struct ivhd_dte_flags to store persistent DTE flags

[Jason Gunthorpe]

On Thu, Oct 31, 2024 at 09:16:18AM +0000, Suravee Suthikulpanit wrote:
> During early initialization, the driver parses IVRS IVHD block to get list
> of downstream devices along with their DTE flags (i.e INITPass, EIntPass,
> NMIPass, SysMgt, Lint0Pass, Lint1Pass). This information is currently
> store in the device DTE, and needs to be preserved when clearing
> and configuring each DTE, which makes it difficult to manage.
> 
> Introduce struct ivhd_dte_flags to store IVHD DTE settings for a device or
> range of devices, which are stored in the amd_ivhd_dev_flags_list during
> initial IVHD parsing.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
>  drivers/iommu/amd/amd_iommu_types.h |  15 ++++
>  drivers/iommu/amd/init.c            | 110 ++++++++++++++++++++--------
>  2 files changed, 96 insertions(+), 29 deletions(-)

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

>  /* sets a specific bit in the device table entry. */
> +static void set_dte_bit(struct dev_table_entry *dte, u8 bit)
> +{
> +	int i = (bit >> 6) & 0x03;
> +	int _bit = bit & 0x3f;
> +
> +	dte->data[i] |= (1UL << _bit);
> +}

It would be nice to see the remaining DEV_ENTRY constants harmonized
with the DTE_ constants so there aren't two schemes for working with
the struct dev_table_entry, but that is an idea for some other series

Jason

Re: [PATCH v7 06/10] iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers

[Jason Gunthorpe]

On Thu, Oct 31, 2024 at 09:16:20AM +0000, Suravee Suthikulpanit wrote:
> @@ -1148,6 +1146,28 @@ static bool copy_device_table(void)
>  	return true;
>  }
>  
> +struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 devid)
> +{
> +	u16 f = 0, l = 0xFFFF;
> +	struct ivhd_dte_flags *e;
> +	struct dev_table_entry *dte = NULL;
> +
> +	for_each_ivhd_dte_flags(e) {

Maybe the list head should be on the iommu? I don't know how long it
would be if it is worthwhile.

> +		/*
> +		 * Need to go through the whole list to find the smallest range,
> +		 * which contains the devid. Then store it in f and l variables.
> +		 */
> +		if ((e->devid_first >= devid) && (e->devid_last <= devid)) {
> +			if (f < e->devid_first)
> +				f = e->devid_first;
> +			if (e->devid_last < l)
> +				l = e->devid_last;
> +			dte = &(e->dte);
> +		}

f and l are never used, why calculate them?

Isn't (e->devid_first >= devid) not the right way to check if devid
falls within a range?

Based on the comment it seems like you want something like this??

struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 devid)
{
	struct dev_table_entry *dte = NULL;
	unsigned int best_len = UINT_MAX;
	struct ivhd_dte_flags *e;

	for_each_ivhd_dte_flags(e) {
		/*
		 * Need to go through the whole list to find the smallest range,
		 * which contains the devid. Then store it in f and l variables.
		 */
		if ((e->devid_first <= devid) && (e->devid_last >= devid)) {
			unsigned int len = e->devid_last - e->devid_first;

			if (len < best_len) {
				dte = &(e->dte);
				best_len = len;
			}
		}
	}
	return dte;
}

(and it would be smart to sort the linked list by size, but again I
don't know how big it is if it is worthwile complexity)

The DTE code looks OK

Jason

Re: [PATCH v7 10/10] iommu/amd: Remove amd_iommu_apply_erratum_63()

[Jason Gunthorpe]

On Thu, Oct 31, 2024 at 09:16:24AM +0000, Suravee Suthikulpanit wrote:
> Also replace __set_dev_entry_bit() with set_dte_bit() and remove unused
> helper functions.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
>  drivers/iommu/amd/amd_iommu.h |  1 -
>  drivers/iommu/amd/init.c      | 50 +++--------------------------------
>  2 files changed, 3 insertions(+), 48 deletions(-)

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

Jason

Re: [PATCH v7 06/10] iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers

[Suthikulpanit, Suravee]

On 10/31/2024 7:53 PM, Jason Gunthorpe wrote:
> On Thu, Oct 31, 2024 at 09:16:20AM +0000, Suravee Suthikulpanit wrote:
>> @@ -1148,6 +1146,28 @@ static bool copy_device_table(void)
>>   	return true;
>>   }
>>   
>> +struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 devid)
>> +{
>> +	u16 f = 0, l = 0xFFFF;
>> +	struct ivhd_dte_flags *e;
>> +	struct dev_table_entry *dte = NULL;
>> +
>> +	for_each_ivhd_dte_flags(e) {
> 
> Maybe the list head should be on the iommu? I don't know how long it
> would be if it is worthwhile.
> 
>> +		/*
>> +		 * Need to go through the whole list to find the smallest range,
>> +		 * which contains the devid. Then store it in f and l variables.
>> +		 */
>> +		if ((e->devid_first >= devid) && (e->devid_last <= devid)) {
>> +			if (f < e->devid_first)
>> +				f = e->devid_first;
>> +			if (e->devid_last < l)
>> +				l = e->devid_last;
>> +			dte = &(e->dte);
>> +		}
> 
> f and l are never used, why calculate them?
> 
> Isn't (e->devid_first >= devid) not the right way to check if devid
> falls within a range?

Actually, I missed one line. I intended to do:

+         if ((e->devid_first >= devid) && (e->devid_last <= devid) &&
+             (f <= e->devid_first) && (e->devid_last <= l)) {

The IVHD device entry can be defined for a range of devices (range 
entry) or for a selected device (dev entry). So, a particular devid 
could fall into both a range entry and a dev entry. For example:

AMD-Vi: device: 0000:00:00.2 cap: 0040 flags: 30 info 0000
AMD-Vi:   DEV_SELECT_RANGE_START       devid: 0000:00:00.3 flags: 0x0
AMD-Vi:   DEV_RANGE_END                devid: 0000:1f:1f.6
AMD-Vi:   DEV_SPECIAL(HPET[0])         devid: 0000:00:14.0, flags: 0x0
AMD-Vi:   DEV_SPECIAL(IOAPIC[128])     devid: 0000:00:14.0, flags: 0xd7
AMD-Vi:   DEV_SPECIAL(IOAPIC[242])     devid: 0000:00:00.1, flags: 0x0
AMD-Vi:   DEV_ACPI_HID(AMDI0020[ID00]) devid: 0000:00:14.5, flags: 0x40
AMD-Vi:   DEV_ACPI_HID(AMDI0020[ID01]) devid: 0000:00:14.5, flags: 0x40
AMD-Vi:   DEV_ACPI_HID(AMDI0020[ID02]) devid: 0000:00:14.5, flags: 0x40
AMD-Vi:   DEV_ACPI_HID(AMDI0020[ID03]) devid: 0000:00:14.5, flags: 0x40
AMD-Vi:   DEV_ACPI_HID(AMDI0095[ID00]) devid: 0000:00:00.4, flags: 0x30

Note that the logic only store the entry w/ flags != 0.

For devid 0000:00:14.0, we want to get the dev entry

     DEV_SPECIAL(IOAPIC[128])     devid: 0000:00:14.0, flags: 0xd7

> Based on the comment it seems like you want something like this??
> 
> struct dev_table_entry *amd_iommu_get_ivhd_dte_flags(u16 devid)
> {
> 	struct dev_table_entry *dte = NULL;
> 	unsigned int best_len = UINT_MAX;
> 	struct ivhd_dte_flags *e;
> 
> 	for_each_ivhd_dte_flags(e) {
> 		/*
> 		 * Need to go through the whole list to find the smallest range,
> 		 * which contains the devid. Then store it in f and l variables.
> 		 */
> 		if ((e->devid_first <= devid) && (e->devid_last >= devid)) {
> 			unsigned int len = e->devid_last - e->devid_first;
> 
> 			if (len < best_len) {
> 				dte = &(e->dte);
> 				best_len = len;
> 			}
> 		}
> 	}
> 	return dte;
> }

This logic would work also. Thanks.

> (and it would be smart to sort the linked list by size, but again I
> don't know how big it is if it is worthwile complexity)

The list should not be too long (only a few entries). So, I think it 
would be okay to just keep one list for the whole system.

However, we would need to also add logic to check PCI segment ID, since 
the device table is per PCI segment.

I will update and send out V8.

Thanks,
Suravee