[Qemu-devel] [PATCH v8 13/25] q35: ioapic: add support for emulated IOAPIC IR

[Peter Xu <peterx@redhat.com>]

This patch translates all IOAPIC interrupts into MSI ones. One pseudo
ioapic address space is added to transfer the MSI message. By default,
it will be system memory address space. When IR is enabled, it will be
IOMMU address space.

Currently, only emulated IOAPIC is supported.

Idea suggested by Jan Kiszka and Rita Sinha in the following patch:

https://lists.gnu.org/archive/html/qemu-devel/2016-03/msg01933.html

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/i386/pc.c                      |  3 +++
 hw/intc/ioapic.c                  | 28 ++++++++++++++++++++++++----
 hw/pci-host/q35.c                 |  4 ++++
 include/hw/i386/apic-msidef.h     |  1 +
 include/hw/i386/ioapic_internal.h |  1 +
 include/hw/i386/pc.h              |  4 ++++
 6 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index e29ccc8..8d523f8 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1396,6 +1396,9 @@ void pc_memory_init(PCMachineState *pcms,
         rom_add_option(option_rom[i].name, option_rom[i].bootindex);
     }
     pcms->fw_cfg = fw_cfg;
+
+    /* Init default IOAPIC address space */
+    pcms->ioapic_as = &address_space_memory;
 }
 
 qemu_irq pc_allocate_cpu_irq(void)
diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index 273bb08..36dd42a 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -29,6 +29,8 @@
 #include "hw/i386/ioapic_internal.h"
 #include "include/hw/pci/msi.h"
 #include "sysemu/kvm.h"
+#include "target-i386/cpu.h"
+#include "hw/i386/apic-msidef.h"
 
 //#define DEBUG_IOAPIC
 
@@ -50,13 +52,15 @@ extern int ioapic_no;
 
 static void ioapic_service(IOAPICCommonState *s)
 {
+    AddressSpace *ioapic_as = PC_MACHINE(qdev_get_machine())->ioapic_as;
+    uint32_t addr, data;
     uint8_t i;
     uint8_t trig_mode;
     uint8_t vector;
     uint8_t delivery_mode;
     uint32_t mask;
     uint64_t entry;
-    uint8_t dest;
+    uint16_t dest_idx;
     uint8_t dest_mode;
 
     for (i = 0; i < IOAPIC_NUM_PINS; i++) {
@@ -67,7 +71,14 @@ static void ioapic_service(IOAPICCommonState *s)
             entry = s->ioredtbl[i];
             if (!(entry & IOAPIC_LVT_MASKED)) {
                 trig_mode = ((entry >> IOAPIC_LVT_TRIGGER_MODE_SHIFT) & 1);
-                dest = entry >> IOAPIC_LVT_DEST_SHIFT;
+                /*
+                 * By default, this would be dest_id[8] +
+                 * reserved[8]. When IR is enabled, this would be
+                 * interrupt_index[15] + interrupt_format[1]. This
+                 * field never means anything, but only used to
+                 * generate corresponding MSI.
+                 */
+                dest_idx = entry >> IOAPIC_LVT_DEST_IDX_SHIFT;
                 dest_mode = (entry >> IOAPIC_LVT_DEST_MODE_SHIFT) & 1;
                 delivery_mode =
                     (entry >> IOAPIC_LVT_DELIV_MODE_SHIFT) & IOAPIC_DM_MASK;
@@ -97,8 +108,17 @@ static void ioapic_service(IOAPICCommonState *s)
 #else
                 (void)coalesce;
 #endif
-                apic_deliver_irq(dest, dest_mode, delivery_mode, vector,
-                                 trig_mode);
+                /* No matter whether IR is enabled, we translate
+                 * the IOAPIC message into a MSI one, and its
+                 * address space will decide whether we need a
+                 * translation. */
+                addr = APIC_DEFAULT_ADDRESS | \
+                    (dest_idx << MSI_ADDR_DEST_IDX_SHIFT) |
+                    (dest_mode << MSI_ADDR_DEST_MODE_SHIFT);
+                data = (vector << MSI_DATA_VECTOR_SHIFT) |
+                    (trig_mode << MSI_DATA_TRIGGER_SHIFT) |
+                    (delivery_mode << MSI_DATA_DELIVERY_MODE_SHIFT);
+                stl_le_phys(ioapic_as, addr, data);
             }
         }
     }
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 6835da1..f3d47ad 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -435,6 +435,7 @@ static AddressSpace *q35_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
 
 static void mch_init_dmar(MCHPCIState *mch)
 {
+    PCMachineState *pcms = PC_MACHINE(qdev_get_machine());
     PCIBus *pci_bus = PCI_BUS(qdev_get_parent_bus(DEVICE(mch)));
 
     mch->iommu = INTEL_IOMMU_DEVICE(qdev_create(NULL, TYPE_INTEL_IOMMU_DEVICE));
@@ -444,6 +445,9 @@ static void mch_init_dmar(MCHPCIState *mch)
     sysbus_mmio_map(SYS_BUS_DEVICE(mch->iommu), 0, Q35_HOST_BRIDGE_IOMMU_ADDR);
 
     pci_setup_iommu(pci_bus, q35_host_dma_iommu, mch->iommu);
+    /* Pseudo address space under root PCI bus. */
+    pcms->ioapic_as = q35_host_dma_iommu(pci_bus, mch->iommu,
+                                         Q35_PSEUDO_DEVFN_IOAPIC);
 }
 
 static void mch_realize(PCIDevice *d, Error **errp)
diff --git a/include/hw/i386/apic-msidef.h b/include/hw/i386/apic-msidef.h
index 6e2eb71..8b4d4cc 100644
--- a/include/hw/i386/apic-msidef.h
+++ b/include/hw/i386/apic-msidef.h
@@ -25,6 +25,7 @@
 #define MSI_ADDR_REDIRECTION_SHIFT      3
 
 #define MSI_ADDR_DEST_ID_SHIFT          12
+#define MSI_ADDR_DEST_IDX_SHIFT         4
 #define  MSI_ADDR_DEST_ID_MASK          0x00ffff0
 
 #endif /* HW_APIC_MSIDEF_H */
diff --git a/include/hw/i386/ioapic_internal.h b/include/hw/i386/ioapic_internal.h
index cab9e67..31dafb3 100644
--- a/include/hw/i386/ioapic_internal.h
+++ b/include/hw/i386/ioapic_internal.h
@@ -31,6 +31,7 @@
 #define IOAPIC_VERSION                  0x11
 
 #define IOAPIC_LVT_DEST_SHIFT           56
+#define IOAPIC_LVT_DEST_IDX_SHIFT       48
 #define IOAPIC_LVT_MASKED_SHIFT         16
 #define IOAPIC_LVT_TRIGGER_MODE_SHIFT   15
 #define IOAPIC_LVT_REMOTE_IRR_SHIFT     14
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 9ca2309..f41164d 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -72,6 +72,10 @@ struct PCMachineState {
     uint64_t numa_nodes;
     uint64_t *node_mem;
     uint64_t *node_cpu;
+
+    /* Address space used by IOAPIC device. All IOAPIC interrupts
+     * will be translated to MSI messages in the address space. */
+    AddressSpace *ioapic_as;
 };
 
 #define PC_MACHINE_ACPI_DEVICE_PROP "acpi-device"
-- 
2.4.11