[PATCH v2] hw/i386/intel_iommu: Block CFI when necessary

[Yuke Peng]

According to Intel VT-d specification 5.1.4, CFI must be blocked when
Extended Interrupt Mode is enabled or Compatibility format interrupts
are disabled.

Signed-off-by: Yuke Peng <pykfirst@gmail.com>
---
Changes in v2:
- Use subsections for the cfi_enabled field.
- Link to v1: 
https://lore.kernel.org/qemu-devel/20240625112819.862282-1-pykfirst@gmail.com/

---
 hw/i386/intel_iommu.c         | 53 +++++++++++++++++++++++++++++++++--
 hw/i386/trace-events          |  1 +
 include/hw/i386/intel_iommu.h |  1 +
 3 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 5085a6fee3..af9c864bde 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -2410,6 +2410,22 @@ static void vtd_handle_gcmd_ire(IntelIOMMUState *s, bool 
en)
     }
 }
 
+/* Handle Compatibility Format Interrupts Enable/Disable */
+static void vtd_handle_gcmd_cfi(IntelIOMMUState *s, bool en)
+{
+    trace_vtd_cfi_enable(en);
+
+    if (en) {
+        s->cfi_enabled = true;
+        /* Ok - report back to driver */
+        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_CFIS);
+    } else {
+        s->cfi_enabled = false;
+        /* Ok - report back to driver */
+        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_CFIS, 0);
+    }
+}
+
 /* Handle write to Global Command Register */
 static void vtd_handle_gcmd_write(IntelIOMMUState *s)
 {
@@ -2440,6 +2456,10 @@ static void vtd_handle_gcmd_write(IntelIOMMUState *s)
         /* Interrupt remap enable/disable */
         vtd_handle_gcmd_ire(s, val & VTD_GCMD_IRE);
     }
+    if (changed & VTD_GCMD_CFI) {
+        /* Compatibility format interrupts enable/disable */
+        vtd_handle_gcmd_cfi(s, val & VTD_GCMD_CFI);
+    }
 }
 
 /* Handle write to Context Command Register */
@@ -3283,7 +3303,25 @@ static int vtd_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static const VMStateDescription vtd_vmstate = {
+static bool vtd_cfi_needed(void *opaque)
+{
+    IntelIOMMUState *iommu = opaque;
+
+    return iommu->intr_enabled && !iommu->intr_eime;
+}
+
+static const VMStateDescription vmstate_vtd_cfi = {
+    .name = "iommu-intel/cfi",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = vtd_cfi_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_BOOL(cfi_enabled, IntelIOMMUState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription vmstate_vtd = {
     .name = "iommu-intel",
     .version_id = 1,
     .minimum_version_id = 1,
@@ -3306,6 +3344,10 @@ static const VMStateDescription vtd_vmstate = {
         VMSTATE_BOOL(intr_enabled, IntelIOMMUState),
         VMSTATE_BOOL(intr_eime, IntelIOMMUState),
         VMSTATE_END_OF_LIST()
+    },
+    .subsections = (const VMStateDescription * []) {
+        &vmstate_vtd_cfi,
+        NULL
     }
 };
 
@@ -3525,6 +3567,12 @@ static int vtd_interrupt_remap_msi(IntelIOMMUState 
*iommu,
 
     /* This is compatible mode. */
     if (addr.addr.int_mode != VTD_IR_INT_FORMAT_REMAP) {
+        if (iommu->intr_eime || !iommu->cfi_enabled) {
+            if (do_fault) {
+                vtd_report_ir_fault(iommu, sid, VTD_FR_IR_REQ_COMPAT, 0);
+            }
+            return -EINVAL;
+        }
         memcpy(translated, origin, sizeof(*origin));
         goto out;
     }
@@ -3950,6 +3998,7 @@ static void vtd_init(IntelIOMMUState *s)
     s->root_scalable = false;
     s->dmar_enabled = false;
     s->intr_enabled = false;
+    s->cfi_enabled = false;
     s->iq_head = 0;
     s->iq_tail = 0;
     s->iq = 0;
@@ -4243,7 +4292,7 @@ static void vtd_class_init(ObjectClass *klass, void *data)
     X86IOMMUClass *x86_class = X86_IOMMU_DEVICE_CLASS(klass);
 
     dc->reset = vtd_reset;
-    dc->vmsd = &vtd_vmstate;
+    dc->vmsd = &vmstate_vtd;
     device_class_set_props(dc, vtd_properties);
     dc->hotpluggable = false;
     x86_class->realize = vtd_realize;
diff --git a/hw/i386/trace-events b/hw/i386/trace-events
index 53c02d7ac8..ffd87db65f 100644
--- a/hw/i386/trace-events
+++ b/hw/i386/trace-events
@@ -57,6 +57,7 @@ vtd_dmar_translate(uint8_t bus, uint8_t slot, uint8_t func, 
uint64_t iova, uint6
 vtd_dmar_enable(bool en) "enable %d"
 vtd_dmar_fault(uint16_t sid, int fault, uint64_t addr, bool is_write) "sid 
0x%"PRIx16" fault %d addr 0x%"PRIx64" write %d"
 vtd_ir_enable(bool en) "enable %d"
+vtd_cfi_enable(bool en) "enable %d"
 vtd_ir_irte_get(int index, uint64_t lo, uint64_t hi) "index %d low 0x%"PRIx64" 
high 0x%"PRIx64
 vtd_ir_remap(int index, int tri, int vec, int deliver, uint32_t dest, int 
dest_mode) "index %d trigger %d vector %d deliver %d dest 0x%"PRIx32" mode %d"
 vtd_ir_remap_type(const char *type) "%s"
diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index 7fa0a695c8..38e20d0f2c 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -294,6 +294,7 @@ struct IntelIOMMUState {
 
     /* interrupt remapping */
     bool intr_enabled;              /* Whether guest enabled IR */
+    bool cfi_enabled;               /* Whether CFI is enabled */
     dma_addr_t intr_root;           /* Interrupt remapping table pointer */
     uint32_t intr_size;             /* Number of IR table entries */
     bool intr_eime;                 /* Extended interrupt mode enabled */
-- 
2.34.1