amd iommu: Cleanup iommu pci capabilites detection

* Define new structure to represent capability block.
* Remove unnecessary read for unused information.
* Add sanity check into get_iommu_capabilities.
* iommu capability offset is 16 bit not 8 bit, fix that.

Signed-off-by: Wei Wang <wei.wang2@amd.com>
Committed-by: Jan Beulich <jbeulich@suse.com>

3 files changed, 32 insertions, 27 deletions

diff --git a/xen/drivers/passthrough/amd/iommu_detect.c b/xen/drivers/passthrough/amd/iommu_detect.c
index 5113f67544..9ead31d4e6 100644
--- a/xen/drivers/passthrough/amd/iommu_detect.c
+++ b/xen/drivers/passthrough/amd/iommu_detect.c
@@ -48,25 +48,16 @@ static int __init get_iommu_msi_capabilities(
 }
 
 static int __init get_iommu_capabilities(
-    u16 seg, u8 bus, u8 dev, u8 func, u8 cap_ptr, struct amd_iommu *iommu)
+    u16 seg, u8 bus, u8 dev, u8 func, u16 cap_ptr, struct amd_iommu *iommu)
 {
-    u32 cap_header, cap_range, misc_info;
+    u8 type;
 
-    cap_header = pci_conf_read32(seg, bus, dev, func, cap_ptr);
-    iommu->revision = get_field_from_reg_u32(
-        cap_header, PCI_CAP_REV_MASK, PCI_CAP_REV_SHIFT);
-    iommu->pte_not_present_cached = get_field_from_reg_u32(
-        cap_header, PCI_CAP_NP_CACHE_MASK, PCI_CAP_NP_CACHE_SHIFT);
+    iommu->cap.header = pci_conf_read32(seg, bus, dev, func, cap_ptr);
+    type = get_field_from_reg_u32(iommu->cap.header, PCI_CAP_TYPE_MASK,
+                                  PCI_CAP_TYPE_SHIFT);
 
-    cap_range = pci_conf_read32(seg, bus, dev, func,
-                                cap_ptr + PCI_CAP_RANGE_OFFSET);
-    iommu->unit_id = get_field_from_reg_u32(
-        cap_range, PCI_CAP_UNIT_ID_MASK, PCI_CAP_UNIT_ID_SHIFT);
-
-    misc_info = pci_conf_read32(seg, bus, dev, func,
-                                cap_ptr + PCI_MISC_INFO_OFFSET);
-    iommu->msi_number = get_field_from_reg_u32(
-        misc_info, PCI_CAP_MSI_NUMBER_MASK, PCI_CAP_MSI_NUMBER_SHIFT);
+    if ( type != PCI_CAP_TYPE_IOMMU )
+        return -ENODEV;
 
     return 0;
 }
@@ -76,6 +67,7 @@ int __init amd_iommu_detect_one_acpi(void *ivhd)
     struct amd_iommu *iommu;
     u8 bus, dev, func;
     struct acpi_ivhd_block_header *ivhd_block;
+    int rt = 0;
 
     ivhd_block = (struct acpi_ivhd_block_header *)ivhd;
 
@@ -125,12 +117,19 @@ int __init amd_iommu_detect_one_acpi(void *ivhd)
     iommu->ht_tunnel_enable = get_field_from_byte(ivhd_block->header.flags,
                         AMD_IOMMU_ACPI_HT_TUN_ENB_MASK,
                         AMD_IOMMU_ACPI_HT_TUN_ENB_SHIFT);
-    bus = iommu->bdf >> 8;
-    dev = PCI_SLOT(iommu->bdf & 0xFF);
-    func = PCI_FUNC(iommu->bdf & 0xFF);
-    get_iommu_capabilities(iommu->seg, bus, dev, func,
-                           iommu->cap_offset, iommu);
-    get_iommu_msi_capabilities(iommu->seg, bus, dev, func, iommu);
+
+    bus = PCI_BUS(iommu->bdf);
+    dev = PCI_SLOT(iommu->bdf);
+    func = PCI_FUNC(iommu->bdf);
+
+    rt = get_iommu_capabilities(iommu->seg, bus, dev, func,
+                                iommu->cap_offset, iommu);
+    if ( rt )
+        return -ENODEV;
+
+    rt = get_iommu_msi_capabilities(iommu->seg, bus, dev, func, iommu);
+    if ( rt )
+        return -ENODEV;
 
     list_add_tail(&iommu->list, &amd_iommu_head);
 
diff --git a/xen/include/asm-x86/amd-iommu.h b/xen/include/asm-x86/amd-iommu.h
index 5dc97c6766..df36fe25ac 100644
--- a/xen/include/asm-x86/amd-iommu.h
+++ b/xen/include/asm-x86/amd-iommu.h
@@ -36,16 +36,22 @@ struct table_struct {
     unsigned long alloc_size;
 };
 
+typedef struct iommu_cap {
+    uint32_t header;                    /* offset 00h */
+    uint32_t base_low;                  /* offset 04h */
+    uint32_t base_hi;                   /* offset 08h */
+    uint32_t range;                     /* offset 0Ch */
+    uint32_t misc;                      /* offset 10h */
+} iommu_cap_t;
+
 struct amd_iommu {
     struct list_head list;
     spinlock_t lock; /* protect iommu */
 
     u16 seg;
     u16 bdf;
-    u8  cap_offset;
-    u8  revision;
-    u8  unit_id;
-    u8  msi_number;
+    u16 cap_offset;
+    iommu_cap_t cap;
 
     u8 pte_not_present_cached;
     u8 ht_tunnel_support;
diff --git a/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h b/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
index a37e32d8c1..dfcf4d77b9 100644
--- a/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
@@ -74,7 +74,7 @@
 
 #define PCI_CAP_UNIT_ID_MASK    0x0000001F
 #define PCI_CAP_UNIT_ID_SHIFT   0
-#define PCI_MISC_INFO_OFFSET    0x10
+#define PCI_CAP_MISC_INFO_OFFSET    0x10
 #define PCI_CAP_MSI_NUMBER_MASK     0x0000001F
 #define PCI_CAP_MSI_NUMBER_SHIFT    0