intel_iommu: Add support for PCI MSI remap

This patch enables interrupt remapping for PCI devices.

To play the trick, one memory region "iommu_ir" is added as child region
of the original iommu memory region, covering range 0xfeeXXXXX (which is
the address range for APIC). All the writes to this range will be taken
as MSI, and translation is carried out only when IR is enabled.

Idea suggested by Paolo Bonzini.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 241 insertions, 0 deletions

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 6a6cb3b..2e57396 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -1982,6 +1982,240 @@ static Property vtd_properties[] = {
     DEFINE_PROP_END_OF_LIST(),
 };
 
+/* Read IRTE entry with specific index */
+static int vtd_irte_get(IntelIOMMUState *iommu, uint16_t index,
+                        VTD_IRTE *entry)
+{
+    dma_addr_t addr = 0x00;
+
+    addr = iommu->intr_root + index * sizeof(*entry);
+    if (dma_memory_read(&address_space_memory, addr, entry,
+                        sizeof(*entry))) {
+        VTD_DPRINTF(GENERAL, "error: fail to access IR root at 0x%"PRIx64
+                    " + %"PRIu16, iommu->intr_root, index);
+        return -VTD_FR_IR_ROOT_INVAL;
+    }
+
+    if (!entry->present) {
+        VTD_DPRINTF(GENERAL, "error: present flag not set in IRTE"
+                    " entry index %u value 0x%"PRIx64 " 0x%"PRIx64,
+                    index, le64_to_cpu(entry->data[1]),
+                    le64_to_cpu(entry->data[0]));
+        return -VTD_FR_IR_ENTRY_P;
+    }
+
+    if (entry->__reserved_0 || entry->__reserved_1 || \
+        entry->__reserved_2) {
+        VTD_DPRINTF(GENERAL, "error: IRTE entry index %"PRIu16
+                    " reserved fields non-zero: 0x%"PRIx64 " 0x%"PRIx64,
+                    index, le64_to_cpu(entry->data[1]),
+                    le64_to_cpu(entry->data[0]));
+        return -VTD_FR_IR_IRTE_RSVD;
+    }
+
+    /*
+     * TODO: Check Source-ID corresponds to SVT (Source Validation
+     * Type) bits
+     */
+
+    return 0;
+}
+
+/* Fetch IRQ information of specific IR index */
+static int vtd_remap_irq_get(IntelIOMMUState *iommu, uint16_t index, VTDIrq *irq)
+{
+    VTD_IRTE irte = { 0 };
+    int ret = 0;
+
+    ret = vtd_irte_get(iommu, index, &irte);
+    if (ret) {
+        return ret;
+    }
+
+    irq->trigger_mode = irte.trigger_mode;
+    irq->vector = irte.vector;
+    irq->delivery_mode = irte.delivery_mode;
+    /* Not support EIM yet: please refer to vt-d 9.10 DST bits */
+#define  VTD_IR_APIC_DEST_MASK         (0xff00ULL)
+#define  VTD_IR_APIC_DEST_SHIFT        (8)
+    irq->dest = (le32_to_cpu(irte.dest_id) & VTD_IR_APIC_DEST_MASK) >> \
+        VTD_IR_APIC_DEST_SHIFT;
+    irq->dest_mode = irte.dest_mode;
+    irq->redir_hint = irte.redir_hint;
+
+    VTD_DPRINTF(IR, "remapping interrupt index %d: trig:%u,vec:%u,"
+                "deliver:%u,dest:%u,dest_mode:%u", index,
+                irq->trigger_mode, irq->vector, irq->delivery_mode,
+                irq->dest, irq->dest_mode);
+
+    return 0;
+}
+
+/* Generate one MSI message from VTDIrq info */
+static void vtd_generate_msi_message(VTDIrq *irq, MSIMessage *msg_out)
+{
+    VTD_MSIMessage msg = {};
+
+    /* Generate address bits */
+    msg.dest_mode = irq->dest_mode;
+    msg.redir_hint = irq->redir_hint;
+    msg.dest = irq->dest;
+    msg.__addr_head = cpu_to_le32(0xfee);
+    /* Keep this from original MSI address bits */
+    msg.__not_used = irq->msi_addr_last_bits;
+
+    /* Generate data bits */
+    msg.vector = irq->vector;
+    msg.delivery_mode = irq->delivery_mode;
+    msg.level = 1;
+    msg.trigger_mode = irq->trigger_mode;
+
+    msg_out->address = msg.msi_addr;
+    msg_out->data = msg.msi_data;
+}
+
+/* Interrupt remapping for MSI/MSI-X entry */
+static int vtd_interrupt_remap_msi(IntelIOMMUState *iommu,
+                                   MSIMessage *origin,
+                                   MSIMessage *translated)
+{
+    int ret = 0;
+    VTD_IR_MSIAddress addr;
+    uint16_t index;
+    VTDIrq irq = {0};
+
+    assert(origin && translated);
+
+    if (!iommu || !iommu->intr_enabled) {
+        goto do_not_translate;
+    }
+
+    if (origin->address & VTD_MSI_ADDR_HI_MASK) {
+        VTD_DPRINTF(GENERAL, "error: MSI addr high 32 bits nonzero"
+                    " during interrupt remapping: 0x%"PRIx32,
+                    (uint32_t)((origin->address & VTD_MSI_ADDR_HI_MASK) >> \
+                    VTD_MSI_ADDR_HI_SHIFT));
+        return -VTD_FR_IR_REQ_RSVD;
+    }
+
+    addr.data = origin->address & VTD_MSI_ADDR_LO_MASK;
+    if (le16_to_cpu(addr.__head) != 0xfee) {
+        VTD_DPRINTF(GENERAL, "error: MSI addr low 32 bits invalid: "
+                    "0x%"PRIx32, addr.data);
+        return -VTD_FR_IR_REQ_RSVD;
+    }
+
+    /* This is compatible mode. */
+    if (addr.int_mode != VTD_IR_INT_FORMAT_REMAP) {
+        goto do_not_translate;
+    }
+
+    index = addr.index_h << 15 | le16_to_cpu(addr.index_l);
+
+#define  VTD_IR_MSI_DATA_SUBHANDLE       (0x0000ffff)
+#define  VTD_IR_MSI_DATA_RESERVED        (0xffff0000)
+
+    if (addr.sub_valid) {
+        /* See VT-d spec 5.1.2.2 and 5.1.3 on subhandle */
+        index += origin->data & VTD_IR_MSI_DATA_SUBHANDLE;
+    }
+
+    ret = vtd_remap_irq_get(iommu, index, &irq);
+    if (ret) {
+        return ret;
+    }
+
+    if (addr.sub_valid) {
+        VTD_DPRINTF(IR, "received MSI interrupt");
+        if (origin->data & VTD_IR_MSI_DATA_RESERVED) {
+            VTD_DPRINTF(GENERAL, "error: MSI data bits non-zero for "
+                        "interrupt remappable entry: 0x%"PRIx32,
+                        origin->data);
+            return -VTD_FR_IR_REQ_RSVD;
+        }
+    } else {
+        uint8_t vector = origin->data & 0xff;
+        VTD_DPRINTF(IR, "received IOAPIC interrupt");
+        /* IOAPIC entry vector should be aligned with IRTE vector
+         * (see vt-d spec 5.1.5.1). */
+        if (vector != irq.vector) {
+            VTD_DPRINTF(GENERAL, "IOAPIC vector inconsistent: "
+                        "entry: %d, IRTE: %d, index: %d",
+                        vector, irq.vector, index);
+        }
+    }
+
+    /*
+     * We'd better keep the last two bits, assuming that guest OS
+     * might modify it. Keep it does not hurt after all.
+     */
+    irq.msi_addr_last_bits = addr.__not_care;
+
+    /* Translate VTDIrq to MSI message */
+    vtd_generate_msi_message(&irq, translated);
+
+    VTD_DPRINTF(IR, "mapping MSI 0x%"PRIx64":0x%"PRIx32 " -> "
+                "0x%"PRIx64":0x%"PRIx32, origin->address, origin->data,
+                translated->address, translated->data);
+    return 0;
+
+do_not_translate:
+    memcpy(translated, origin, sizeof(*origin));
+    return 0;
+}
+
+static MemTxResult vtd_mem_ir_read(void *opaque, hwaddr addr,
+                                   uint64_t *data, unsigned size,
+                                   MemTxAttrs attrs)
+{
+    return MEMTX_OK;
+}
+
+static MemTxResult vtd_mem_ir_write(void *opaque, hwaddr addr,
+                                    uint64_t value, unsigned size,
+                                    MemTxAttrs attrs)
+{
+    int ret = 0;
+    MSIMessage from = {0}, to = {0};
+
+    from.address = (uint64_t) addr + VTD_INTERRUPT_ADDR_FIRST;
+    from.data = (uint32_t) value;
+
+    ret = vtd_interrupt_remap_msi(opaque, &from, &to);
+    if (ret) {
+        /* TODO: report error */
+        VTD_DPRINTF(GENERAL, "int remap fail for addr 0x%"PRIx64
+                    " data 0x%"PRIx32, from.address, from.data);
+        /* Drop this interrupt */
+        return MEMTX_ERROR;
+    }
+
+    VTD_DPRINTF(IR, "delivering MSI 0x%"PRIx64":0x%"PRIx32
+                " for device sid 0x%04x",
+                to.address, to.data, sid);
+
+    if (dma_memory_write(&address_space_memory, to.address,
+                         &to.data, size)) {
+        VTD_DPRINTF(GENERAL, "error: fail to write 0x%"PRIx64
+                    " value 0x%"PRIx32, to.address, to.data);
+    }
+
+    return MEMTX_OK;
+}
+
+static const MemoryRegionOps vtd_mem_ir_ops = {
+    .read_with_attrs = vtd_mem_ir_read,
+    .write_with_attrs = vtd_mem_ir_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+};
 
 VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
 {
@@ -2009,6 +2243,11 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
         vtd_dev_as->context_cache_entry.context_cache_gen = 0;
         memory_region_init_iommu(&vtd_dev_as->iommu, OBJECT(s),
                                  &s->iommu_ops, "intel_iommu", UINT64_MAX);
+        memory_region_init_io(&vtd_dev_as->iommu_ir, OBJECT(s),
+                              &vtd_mem_ir_ops, s, "intel_iommu_ir",
+                              VTD_INTERRUPT_ADDR_SIZE);
+        memory_region_add_subregion(&vtd_dev_as->iommu, VTD_INTERRUPT_ADDR_FIRST,
+                                    &vtd_dev_as->iommu_ir);
         address_space_init(&vtd_dev_as->as,
                            &vtd_dev_as->iommu, "intel_iommu");
     }
diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
index 2a9987f..e1a08cb 100644
--- a/hw/i386/intel_iommu_internal.h
+++ b/hw/i386/intel_iommu_internal.h
@@ -110,6 +110,8 @@
 /* Interrupt Address Range */
 #define VTD_INTERRUPT_ADDR_FIRST    0xfee00000ULL
 #define VTD_INTERRUPT_ADDR_LAST     0xfeefffffULL
+#define VTD_INTERRUPT_ADDR_SIZE     (VTD_INTERRUPT_ADDR_LAST - \
+                                     VTD_INTERRUPT_ADDR_FIRST + 1)
 
 /* The shift of source_id in the key of IOTLB hash table */
 #define VTD_IOTLB_SID_SHIFT         36