[RFC][PATCH v2 3/4] KVM: x86: Wire up MSI support for in-kernel irqchip

[Jan Kiszka <jan.kiszka@xxxxxx>]

From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>

Catch writes to the MSI MMIO region in the KVM APIC and forward them to
the kernel. Provide the kernel support GSI routing, this allows to
enable MSI support also for in-kernel irqchip mode.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
 hw/apic.c     |    3 +++
 hw/kvm/apic.c |   33 +++++++++++++++++++++++++++++++--
 hw/pc.c       |    5 -----
 3 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/hw/apic.c b/hw/apic.c
index 4eeaf88..5fbf01c 100644
--- a/hw/apic.c
+++ b/hw/apic.c
@@ -19,6 +19,7 @@
 #include "apic_internal.h"
 #include "apic.h"
 #include "ioapic.h"
+#include "msi.h"
 #include "host-utils.h"
 #include "trace.h"
 #include "pc.h"
@@ -862,6 +863,8 @@ static void apic_init(APICCommonState *s)
 
     s->timer = qemu_new_timer_ns(vm_clock, apic_timer, s);
     local_apics[s->idx] = s;
+
+    msi_supported = true;
 }
 
 static void apic_class_init(ObjectClass *klass, void *data)
diff --git a/hw/kvm/apic.c b/hw/kvm/apic.c
index ffe7a52..7d83b1a 100644
--- a/hw/kvm/apic.c
+++ b/hw/kvm/apic.c
@@ -10,6 +10,7 @@
  * See the COPYING file in the top-level directory.
  */
 #include "hw/apic_internal.h"
+#include "hw/msi.h"
 #include "kvm.h"
 
 static inline void kvm_apic_set_reg(struct kvm_lapic_state *kapic,
@@ -145,10 +146,38 @@ static void kvm_apic_external_nmi(APICCommonState *s)
     run_on_cpu(s->cpu_env, do_inject_external_nmi, s);
 }
 
+static uint64_t kvm_apic_mem_read(void *opaque, target_phys_addr_t addr,
+                                  unsigned size)
+{
+    return -1U;
+}
+
+static void kvm_apic_mem_write(void *opaque, target_phys_addr_t addr,
+                               uint64_t data, unsigned size)
+{
+    int ret;
+
+    ret = kvm_irqchip_send_msi(kvm_state, addr, data);
+    if (ret < 0) {
+        fprintf(stderr, "KVM: injection failed, MSI lost (%s)\n",
+                strerror(-ret));
+    }
+}
+
+static const MemoryRegionOps kvm_apic_io_ops = {
+    .read = kvm_apic_mem_read,
+    .write = kvm_apic_mem_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
 static void kvm_apic_init(APICCommonState *s)
 {
-    memory_region_init_reservation(&s->io_memory, "kvm-apic-msi",
-                                   MSI_SPACE_SIZE);
+    memory_region_init_io(&s->io_memory, &kvm_apic_io_ops, s, "kvm-apic-msi",
+                          MSI_SPACE_SIZE);
+
+    if (kvm_has_gsi_routing()) {
+        msi_supported = true;
+    }
 }
 
 static void kvm_apic_class_init(ObjectClass *klass, void *data)
diff --git a/hw/pc.c b/hw/pc.c
index 83a1b5b..fab620a 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -907,11 +907,6 @@ static DeviceState *apic_init(void *env, uint8_t apic_id)
         apic_mapped = 1;
     }
 
-    /* KVM does not support MSI yet. */
-    if (!kvm_irqchip_in_kernel()) {
-        msi_supported = true;
-    }
-
     return dev;
 }
 
-- 
1.7.3.4

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