[PATCH v3 2/3] iommu/amd: Do not convert IVMD exclusion range to unity range

[Sairaj Kodilkar <sarunkod@amd.com>]

From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

Original problem was there could be multiple IVMD exclusion entries
conflicting over a single exclusion range supported in older Linux
kernel. The fix was first introduced in commit 387caf0b759a ("iommu/amd:
Treat per-device exclusion ranges as r/w unity-mapped regions") and in
commit 0bbe4ced53e3 ("iommu/amd: Fix the overwritten field in IVMD header")
, where IVMD exclusions are converted to separate unity_map_entry objects
in pci_seg->unity_map so amd_iommu_get_resv_regions() treated every such
entry as IOMMU_RESV_DIRECT with R/W.

The driver no longer programs the exclusion base/limit registers and
relies on the kernel to keep the IOVA ranges named by exclusion IVMDs
unmapped. Stop forcing exclusion entries to RW-unity. Store the raw
IVMD flags in struct unity_map_entry instead of a pre-shifted
protection value, and derive the reserved region from those flags.
Exclusion entries are now reported as IOMMU_RESV_RESERVED with no
read/write permission.

Reject unity entries that grant neither IR nor IW with a FW_BUG
message, and warn about invalid flag combinations and unknown flag bits

Fixes: 0bbe4ced53e3 ("iommu/amd: Fix the overwritten field in IVMD header")
Cc: Baoquan He <bhe@redhat.com>
Cc: Adrian Huang <ahuang12@lenovo.com>
Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adam Pelka <adampelka26@gmail.com>
---
 drivers/iommu/amd/amd_iommu_types.h | 12 +++++++-----
 drivers/iommu/amd/init.c            | 26 +++++++++-----------------
 drivers/iommu/amd/iommu.c           | 21 +++++++++++++++++++--
 3 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 678ceddd711c..bcb88b476167 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -368,9 +368,11 @@
 /* DTE[128:179] | DTE[184:191] */
 #define DTE_DATA2_INTR_MASK	~GENMASK_ULL(55, 52)
 
-#define IOMMU_PROT_MASK 0x03
-#define IOMMU_PROT_IR 0x01
-#define IOMMU_PROT_IW 0x02
+#define IVMD_FLAG_UNITY		BIT(0)
+#define IVMD_FLAG_IR		BIT(1)
+#define IVMD_FLAG_IW		BIT(2)
+#define IVMD_FLAG_EXCL		BIT(3)
+#define IVMD_FLAG_MASK		GENMASK_U32(3, 0)
 
 /* IOMMU capabilities */
 #define IOMMU_CAP_IOTLB   24
@@ -880,8 +882,8 @@ struct unity_map_entry {
 	/* end address to unity map (including) */
 	u64 address_end;
 
-	/* required protection */
-	int prot;
+	/* IVMD flags for the entry */
+	u8 flags;
 };
 
 /*
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 13c96feed64f..1f0ca675df1c 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -70,11 +70,6 @@
 #define IVHD_FLAG_RESPASSPW_EN_MASK     0x04
 #define IVHD_FLAG_ISOC_EN_MASK          0x08
 
-#define IVMD_FLAG_EXCL_RANGE            0x08
-#define IVMD_FLAG_IW                    0x04
-#define IVMD_FLAG_IR                    0x02
-#define IVMD_FLAG_UNITY_MAP             0x01
-
 #define ACPI_DEVFLAG_INITPASS           0x01
 #define ACPI_DEVFLAG_EXTINT             0x02
 #define ACPI_DEVFLAG_NMI                0x04
@@ -2636,6 +2631,13 @@ static int __init init_unity_map_range(struct ivmd_header *m,
 	struct amd_iommu_pci_seg *pci_seg;
 	char *s;
 
+	if ((m->flags & IVMD_FLAG_UNITY) &&
+	    !(m->flags & (IVMD_FLAG_IR | IVMD_FLAG_IW | IVMD_FLAG_EXCL))) {
+		pr_err(FW_BUG "IVMD type %#x devid %#x range %#llx+%#llx: Unity set without IR/IW, ignoring\n",
+		       m->type, m->devid, m->range_start, m->range_length);
+		return -EINVAL;
+	}
+
 	pci_seg = get_pci_segment(m->pci_seg, ivrs_base);
 	if (pci_seg == NULL)
 		return -ENOMEM;
@@ -2665,17 +2667,7 @@ static int __init init_unity_map_range(struct ivmd_header *m,
 	}
 	e->address_start = PAGE_ALIGN(m->range_start);
 	e->address_end = e->address_start + PAGE_ALIGN(m->range_length);
-	e->prot = m->flags >> 1;
-
-	/*
-	 * Treat per-device exclusion ranges as r/w unity-mapped regions
-	 * since some buggy BIOSes might lead to the overwritten exclusion
-	 * range (exclusion_start and exclusion_length members). This
-	 * happens when there are multiple exclusion ranges (IVMD entries)
-	 * defined in ACPI table.
-	 */
-	if (m->flags & IVMD_FLAG_EXCL_RANGE)
-		e->prot = (IVMD_FLAG_IW | IVMD_FLAG_IR) >> 1;
+	e->flags = m->flags;
 
 	DUMP_printk("%s devid_start: %04x:%02x:%02x.%x devid_end: "
 		    "%04x:%02x:%02x.%x range_start: %016llx range_end: %016llx"
@@ -2702,7 +2694,7 @@ static int __init init_memory_definitions(struct acpi_table_header *table)
 
 	while (p < end) {
 		m = (struct ivmd_header *)p;
-		if (m->flags & (IVMD_FLAG_UNITY_MAP | IVMD_FLAG_EXCL_RANGE))
+		if (m->flags & (IVMD_FLAG_UNITY | IVMD_FLAG_EXCL))
 			init_unity_map_range(m, table);
 
 		p += m->length;
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 56262f6b1f70..699b5f530f11 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3120,12 +3120,29 @@ static void amd_iommu_get_resv_regions(struct device *dev,
 		if (devid < entry->devid_start || devid > entry->devid_end)
 			continue;
 
+		/*
+		 * IVMD_FLAG_UNITY, IVMD_FLAG_IR, IVMD_FLAG_IW are ignored if
+		 * IVMD_FLAG_EXCL is set.
+		 */
+		if ((entry->flags & IVMD_FLAG_EXCL) &&
+		    (entry->flags & (IVMD_FLAG_UNITY | IVMD_FLAG_IR | IVMD_FLAG_IW)))
+			pr_err(FW_BUG "%s: Invalid IVMD flags combination: %#02x for sbdf=%#x. Ignore IW/IR/Unity flags\n",
+			       __func__, entry->flags, sbdf);
+
+		if (entry->flags & ~IVMD_FLAG_MASK)
+			pr_err("%s: Unknown flags: %#02x for sbdf=%#x\n",
+			       __func__, entry->flags & ~IVMD_FLAG_MASK, sbdf);
+
 		type   = IOMMU_RESV_DIRECT;
 		length = entry->address_end - entry->address_start;
-		if (entry->prot & IOMMU_PROT_IR)
+		if (entry->flags & IVMD_FLAG_IR)
 			prot |= IOMMU_READ;
-		if (entry->prot & IOMMU_PROT_IW)
+		if (entry->flags & IVMD_FLAG_IW)
 			prot |= IOMMU_WRITE;
+		if (entry->flags & IVMD_FLAG_EXCL) {
+			type = IOMMU_RESV_RESERVED;
+			prot = 0;
+		}
 
 		region = iommu_alloc_resv_region(entry->address_start,
 						 length, prot, type,
-- 
2.34.1