[PATCH] hw/i386/intel_iommu: Fix endianness problems related to VTD_IR_TableEntry

[Thomas Huth]

The code already tries to do some endianness handling here, but
currently fails badly:
- While it already swaps the data when logging errors / tracing, it fails
  to byteswap the value before e.g. accessing entry->irte.present
- entry->irte.source_id is swapped with le32_to_cpu(), though this is
  a 16-bit value
- The whole union is apparently supposed to be swapped via the 64-bit
  data[2] array, but the struct is a mixture between 32 bit values
  (the first 8 bytes) and 64 bit values (the second 8 bytes), so this
  cannot work as expected.

Fix it by converting the struct to two proper 64-bit bitfields, and
by swapping the values only once for everybody right after reading
the data from memory.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 Note: There are more endianness issues in the code, I haven't figured
       out all of them yet, Linux fails to boot in the guest when I use
       this device on a s390x host. But I wanted to publish this patch
       now already since this should also fix the "issue" with the Clang
       ms_struct packing that we recently discussed on the mailing list.

 include/hw/i386/intel_iommu.h | 50 ++++++++++++++++++-----------------
 hw/i386/intel_iommu.c         | 16 +++++------
 2 files changed, 34 insertions(+), 32 deletions(-)

diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index 89dcbc5e1e..7fa0a695c8 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -178,37 +178,39 @@ enum {
 union VTD_IR_TableEntry {
     struct {
 #if HOST_BIG_ENDIAN
-        uint32_t __reserved_1:8;     /* Reserved 1 */
-        uint32_t vector:8;           /* Interrupt Vector */
-        uint32_t irte_mode:1;        /* IRTE Mode */
-        uint32_t __reserved_0:3;     /* Reserved 0 */
-        uint32_t __avail:4;          /* Available spaces for software */
-        uint32_t delivery_mode:3;    /* Delivery Mode */
-        uint32_t trigger_mode:1;     /* Trigger Mode */
-        uint32_t redir_hint:1;       /* Redirection Hint */
-        uint32_t dest_mode:1;        /* Destination Mode */
-        uint32_t fault_disable:1;    /* Fault Processing Disable */
-        uint32_t present:1;          /* Whether entry present/available */
+        uint64_t dest_id:32;         /* Destination ID */
+        uint64_t __reserved_1:8;     /* Reserved 1 */
+        uint64_t vector:8;           /* Interrupt Vector */
+        uint64_t irte_mode:1;        /* IRTE Mode */
+        uint64_t __reserved_0:3;     /* Reserved 0 */
+        uint64_t __avail:4;          /* Available spaces for software */
+        uint64_t delivery_mode:3;    /* Delivery Mode */
+        uint64_t trigger_mode:1;     /* Trigger Mode */
+        uint64_t redir_hint:1;       /* Redirection Hint */
+        uint64_t dest_mode:1;        /* Destination Mode */
+        uint64_t fault_disable:1;    /* Fault Processing Disable */
+        uint64_t present:1;          /* Whether entry present/available */
 #else
-        uint32_t present:1;          /* Whether entry present/available */
-        uint32_t fault_disable:1;    /* Fault Processing Disable */
-        uint32_t dest_mode:1;        /* Destination Mode */
-        uint32_t redir_hint:1;       /* Redirection Hint */
-        uint32_t trigger_mode:1;     /* Trigger Mode */
-        uint32_t delivery_mode:3;    /* Delivery Mode */
-        uint32_t __avail:4;          /* Available spaces for software */
-        uint32_t __reserved_0:3;     /* Reserved 0 */
-        uint32_t irte_mode:1;        /* IRTE Mode */
-        uint32_t vector:8;           /* Interrupt Vector */
-        uint32_t __reserved_1:8;     /* Reserved 1 */
+        uint64_t present:1;          /* Whether entry present/available */
+        uint64_t fault_disable:1;    /* Fault Processing Disable */
+        uint64_t dest_mode:1;        /* Destination Mode */
+        uint64_t redir_hint:1;       /* Redirection Hint */
+        uint64_t trigger_mode:1;     /* Trigger Mode */
+        uint64_t delivery_mode:3;    /* Delivery Mode */
+        uint64_t __avail:4;          /* Available spaces for software */
+        uint64_t __reserved_0:3;     /* Reserved 0 */
+        uint64_t irte_mode:1;        /* IRTE Mode */
+        uint64_t vector:8;           /* Interrupt Vector */
+        uint64_t __reserved_1:8;     /* Reserved 1 */
+        uint64_t dest_id:32;         /* Destination ID */
 #endif
-        uint32_t dest_id;            /* Destination ID */
-        uint16_t source_id;          /* Source-ID */
 #if HOST_BIG_ENDIAN
         uint64_t __reserved_2:44;    /* Reserved 2 */
         uint64_t sid_vtype:2;        /* Source-ID Validation Type */
         uint64_t sid_q:2;            /* Source-ID Qualifier */
+        uint64_t source_id:16;       /* Source-ID */
 #else
+        uint64_t source_id:16;       /* Source-ID */
         uint64_t sid_q:2;            /* Source-ID Qualifier */
         uint64_t sid_vtype:2;        /* Source-ID Validation Type */
         uint64_t __reserved_2:44;    /* Reserved 2 */
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index b9b629d1b1..3ca71df369 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3328,14 +3328,15 @@ static int vtd_irte_get(IntelIOMMUState *iommu, 
uint16_t index,
         return -VTD_FR_IR_ROOT_INVAL;
     }
 
-    trace_vtd_ir_irte_get(index, le64_to_cpu(entry->data[1]),
-                          le64_to_cpu(entry->data[0]));
+    entry->data[0] = le64_to_cpu(entry->data[0]);
+    entry->data[1] = le64_to_cpu(entry->data[1]);
+
+    trace_vtd_ir_irte_get(index, entry->data[1], entry->data[0]);
 
     if (!entry->irte.present) {
         error_report_once("%s: detected non-present IRTE "
                           "(index=%u, high=0x%" PRIx64 ", low=0x%" PRIx64 ")",
-                          __func__, index, le64_to_cpu(entry->data[1]),
-                          le64_to_cpu(entry->data[0]));
+                          __func__, index, entry->data[1], entry->data[0]);
         return -VTD_FR_IR_ENTRY_P;
     }
 
@@ -3343,14 +3344,13 @@ static int vtd_irte_get(IntelIOMMUState *iommu, 
uint16_t index,
         entry->irte.__reserved_2) {
         error_report_once("%s: detected non-zero reserved IRTE "
                           "(index=%u, high=0x%" PRIx64 ", low=0x%" PRIx64 ")",
-                          __func__, index, le64_to_cpu(entry->data[1]),
-                          le64_to_cpu(entry->data[0]));
+                          __func__, index, entry->data[1], entry->data[0]);
         return -VTD_FR_IR_IRTE_RSVD;
     }
 
     if (sid != X86_IOMMU_SID_INVALID) {
         /* Validate IRTE SID */
-        source_id = le32_to_cpu(entry->irte.source_id);
+        source_id = entry->irte.source_id;
         switch (entry->irte.sid_vtype) {
         case VTD_SVT_NONE:
             break;
@@ -3404,7 +3404,7 @@ static int vtd_remap_irq_get(IntelIOMMUState *iommu, 
uint16_t index,
     irq->trigger_mode = irte.irte.trigger_mode;
     irq->vector = irte.irte.vector;
     irq->delivery_mode = irte.irte.delivery_mode;
-    irq->dest = le32_to_cpu(irte.irte.dest_id);
+    irq->dest = irte.irte.dest_id;
     if (!iommu->intr_eime) {
 #define  VTD_IR_APIC_DEST_MASK         (0xff00ULL)
 #define  VTD_IR_APIC_DEST_SHIFT        (8)
-- 
2.39.3