Hi,

On 10/9/25 09:50, Paolo Bonzini wrote:
From: Magnus Kulke <[email protected]>

Rename APIC helper functions to use an accel_* prefix instead of kvm_*
to support use by accelerators other than KVM. This is a preparatory
step for integrating MSHV support with common APIC logic.

Signed-off-by: Magnus Kulke <[email protected]>
Link: 
https://lore.kernel.org/r/[email protected]
[Remove dead definition of mshv_msi_via_irqfd_enabled. - Paolo]
Signed-off-by: Paolo Bonzini <[email protected]>
---
  include/system/accel-irq.h |  37 +++++++++++++
  include/system/mshv.h      |  17 ++++++
  accel/accel-irq.c          | 106 +++++++++++++++++++++++++++++++++++++
  hw/intc/ioapic.c           |  20 ++++---
  hw/virtio/virtio-pci.c     |  21 ++++----
  accel/meson.build          |   2 +-
  6 files changed, 185 insertions(+), 18 deletions(-)
  create mode 100644 include/system/accel-irq.h
  create mode 100644 accel/accel-irq.c

This change seems to introduce a regression with interrupt remapping
when running a VM configured with an intel-iommu device and an assigned
PCI VF. At boot, Linux complains with :

[   15.416794] __common_interrupt: 2.37 No irq handler for vector
[   15.417266] __common_interrupt: 2.37 No irq handler for vector
[   15.417733] __common_interrupt: 2.37 No irq handler for vector
[   15.418202] __common_interrupt: 2.37 No irq handler for vector
[   15.418670] __common_interrupt: 2.37 No irq handler for vector
[   15.419143] __common_interrupt: 2.37 No irq handler for vector
[   15.419608] __common_interrupt: 2.37 No irq handler for vector
[   15.420094] __common_interrupt: 2.37 No irq handler for vector
[   15.420556] __common_interrupt: 2.37 No irq handler for vector


CC’ingg Zhenzhong, Joao, Clement for awareness and their expertise
in intel-iommu and interrupt remapping.

Thanks,

C.




diff --git a/include/system/accel-irq.h b/include/system/accel-irq.h
new file mode 100644
index 00000000000..671fb7dfdbb
--- /dev/null
+++ b/include/system/accel-irq.h
@@ -0,0 +1,37 @@
+/*
+ * Accelerated irqchip abstraction
+ *
+ * Copyright Microsoft, Corp. 2025
+ *
+ * Authors: Ziqiao Zhou <[email protected]>
+ *          Magnus Kulke <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef SYSTEM_ACCEL_IRQ_H
+#define SYSTEM_ACCEL_IRQ_H
+#include "hw/pci/msi.h"
+#include "qemu/osdep.h"
+#include "system/kvm.h"
+#include "system/mshv.h"
+
+static inline bool accel_msi_via_irqfd_enabled(void)
+{
+    return mshv_msi_via_irqfd_enabled() || kvm_msi_via_irqfd_enabled();
+}
+
+static inline bool accel_irqchip_is_split(void)
+{
+    return mshv_msi_via_irqfd_enabled() || kvm_irqchip_is_split();
+}
+
+int accel_irqchip_add_msi_route(KVMRouteChange *c, int vector, PCIDevice *dev);
+int accel_irqchip_update_msi_route(int vector, MSIMessage msg, PCIDevice *dev);
+void accel_irqchip_commit_route_changes(KVMRouteChange *c);
+void accel_irqchip_commit_routes(void);
+void accel_irqchip_release_virq(int virq);
+int accel_irqchip_add_irqfd_notifier_gsi(EventNotifier *n, EventNotifier *rn,
+                                         int virq);
+int accel_irqchip_remove_irqfd_notifier_gsi(EventNotifier *n, int virq);
+#endif
diff --git a/include/system/mshv.h b/include/system/mshv.h
index 342f1ef6a98..2a504ed81f2 100644
--- a/include/system/mshv.h
+++ b/include/system/mshv.h
@@ -22,4 +22,21 @@
  #define CONFIG_MSHV_IS_POSSIBLE
  #endif
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+extern bool mshv_allowed;
+#define mshv_enabled() (mshv_allowed)
+#else /* CONFIG_MSHV_IS_POSSIBLE */
+#define mshv_enabled() false
+#endif
+#define mshv_msi_via_irqfd_enabled() false
+
+/* interrupt */
+int mshv_irqchip_add_msi_route(int vector, PCIDevice *dev);
+int mshv_irqchip_update_msi_route(int virq, MSIMessage msg, PCIDevice *dev);
+void mshv_irqchip_commit_routes(void);
+void mshv_irqchip_release_virq(int virq);
+int mshv_irqchip_add_irqfd_notifier_gsi(const EventNotifier *n,
+                                        const EventNotifier *rn, int virq);
+int mshv_irqchip_remove_irqfd_notifier_gsi(const EventNotifier *n, int virq);
+
  #endif
diff --git a/accel/accel-irq.c b/accel/accel-irq.c
new file mode 100644
index 00000000000..7f864e35c4e
--- /dev/null
+++ b/accel/accel-irq.c
@@ -0,0 +1,106 @@
+/*
+ * Accelerated irqchip abstraction
+ *
+ * Copyright Microsoft, Corp. 2025
+ *
+ * Authors: Ziqiao Zhou <[email protected]>
+ *          Magnus Kulke <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/pci/msi.h"
+
+#include "system/kvm.h"
+#include "system/mshv.h"
+#include "system/accel-irq.h"
+
+int accel_irqchip_add_msi_route(KVMRouteChange *c, int vector, PCIDevice *dev)
+{
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+    if (mshv_msi_via_irqfd_enabled()) {
+        return mshv_irqchip_add_msi_route(vector, dev);
+    }
+#endif
+    if (kvm_enabled()) {
+        return kvm_irqchip_add_msi_route(c, vector, dev);
+    }
+    return -ENOSYS;
+}
+
+int accel_irqchip_update_msi_route(int vector, MSIMessage msg, PCIDevice *dev)
+{
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+    if (mshv_msi_via_irqfd_enabled()) {
+        return mshv_irqchip_update_msi_route(vector, msg, dev);
+    }
+#endif
+    if (kvm_enabled()) {
+        return kvm_irqchip_update_msi_route(kvm_state, vector, msg, dev);
+    }
+    return -ENOSYS;
+}
+
+void accel_irqchip_commit_route_changes(KVMRouteChange *c)
+{
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+    if (mshv_msi_via_irqfd_enabled()) {
+        mshv_irqchip_commit_routes();
+    }
+#endif
+    if (kvm_enabled()) {
+        kvm_irqchip_commit_route_changes(c);
+    }
+}
+
+void accel_irqchip_commit_routes(void)
+{
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+    if (mshv_msi_via_irqfd_enabled()) {
+        mshv_irqchip_commit_routes();
+    }
+#endif
+    if (kvm_enabled()) {
+        kvm_irqchip_commit_routes(kvm_state);
+    }
+}
+
+void accel_irqchip_release_virq(int virq)
+{
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+    if (mshv_msi_via_irqfd_enabled()) {
+        mshv_irqchip_release_virq(virq);
+    }
+#endif
+    if (kvm_enabled()) {
+        kvm_irqchip_release_virq(kvm_state, virq);
+    }
+}
+
+int accel_irqchip_add_irqfd_notifier_gsi(EventNotifier *n, EventNotifier *rn,
+                                         int virq)
+{
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+    if (mshv_msi_via_irqfd_enabled()) {
+        return mshv_irqchip_add_irqfd_notifier_gsi(n, rn, virq);
+    }
+#endif
+    if (kvm_enabled()) {
+        return kvm_irqchip_add_irqfd_notifier_gsi(kvm_state, n, rn, virq);
+    }
+    return -ENOSYS;
+}
+
+int accel_irqchip_remove_irqfd_notifier_gsi(EventNotifier *n, int virq)
+{
+#ifdef CONFIG_MSHV_IS_POSSIBLE
+    if (mshv_msi_via_irqfd_enabled()) {
+        return mshv_irqchip_remove_irqfd_notifier_gsi(n, virq);
+    }
+#endif
+    if (kvm_enabled()) {
+        return kvm_irqchip_remove_irqfd_notifier_gsi(kvm_state, n, virq);
+    }
+    return -ENOSYS;
+}
diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index 133bef852d1..e431d003117 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -30,12 +30,18 @@
  #include "hw/intc/ioapic_internal.h"
  #include "hw/pci/msi.h"
  #include "hw/qdev-properties.h"
+#include "system/accel-irq.h"
  #include "system/kvm.h"
  #include "system/system.h"
  #include "hw/i386/apic-msidef.h"
  #include "hw/i386/x86-iommu.h"
  #include "trace.h"
+
+#if defined(CONFIG_KVM) || defined(CONFIG_MSHV)
+#define ACCEL_GSI_IRQFD_POSSIBLE
+#endif
+
  #define APIC_DELIVERY_MODE_SHIFT 8
  #define APIC_POLARITY_SHIFT 14
  #define APIC_TRIG_MODE_SHIFT 15
@@ -191,10 +197,10 @@ static void ioapic_set_irq(void *opaque, int vector, int 
level)
static void ioapic_update_kvm_routes(IOAPICCommonState *s)
  {
-#ifdef CONFIG_KVM
+#ifdef ACCEL_GSI_IRQFD_POSSIBLE
      int i;
- if (kvm_irqchip_is_split()) {
+    if (accel_irqchip_is_split()) {
          for (i = 0; i < IOAPIC_NUM_PINS; i++) {
              MSIMessage msg;
              struct ioapic_entry_info info;
@@ -202,15 +208,15 @@ static void ioapic_update_kvm_routes(IOAPICCommonState *s)
              if (!info.masked) {
                  msg.address = info.addr;
                  msg.data = info.data;
-                kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
+                accel_irqchip_update_msi_route(i, msg, NULL);
              }
          }
-        kvm_irqchip_commit_routes(kvm_state);
+        accel_irqchip_commit_routes();
      }
  #endif
  }
-#ifdef CONFIG_KVM
+#ifdef ACCEL_KERNEL_GSI_IRQFD_POSSIBLE
  static void ioapic_iec_notifier(void *private, bool global,
                                  uint32_t index, uint32_t mask)
  {
@@ -428,11 +434,11 @@ static const MemoryRegionOps ioapic_io_ops = {
static void ioapic_machine_done_notify(Notifier *notifier, void *data)
  {
-#ifdef CONFIG_KVM
+#ifdef ACCEL_KERNEL_GSI_IRQFD_POSSIBLE
      IOAPICCommonState *s = container_of(notifier, IOAPICCommonState,
                                          machine_done);
- if (kvm_irqchip_is_split()) {
+    if (accel_irqchip_is_split()) {
          X86IOMMUState *iommu = x86_iommu_get_default();
          if (iommu) {
              /* Register this IOAPIC with IOMMU IEC notifier, so that
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 767216d7959..0cdc16217ff 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -34,6 +34,7 @@
  #include "hw/pci/msi.h"
  #include "hw/pci/msix.h"
  #include "hw/loader.h"
+#include "system/accel-irq.h"
  #include "system/kvm.h"
  #include "hw/virtio/virtio-pci.h"
  #include "qemu/range.h"
@@ -825,11 +826,11 @@ static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy 
*proxy,
if (irqfd->users == 0) {
          KVMRouteChange c = kvm_irqchip_begin_route_changes(kvm_state);
-        ret = kvm_irqchip_add_msi_route(&c, vector, &proxy->pci_dev);
+        ret = accel_irqchip_add_msi_route(&c, vector, &proxy->pci_dev);
          if (ret < 0) {
              return ret;
          }
-        kvm_irqchip_commit_route_changes(&c);
+        accel_irqchip_commit_route_changes(&c);
          irqfd->virq = ret;
      }
      irqfd->users++;
@@ -841,7 +842,7 @@ static void kvm_virtio_pci_vq_vector_release(VirtIOPCIProxy 
*proxy,
  {
      VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
      if (--irqfd->users == 0) {
-        kvm_irqchip_release_virq(kvm_state, irqfd->virq);
+        accel_irqchip_release_virq(irqfd->virq);
      }
  }
@@ -850,7 +851,7 @@ static int kvm_virtio_pci_irqfd_use(VirtIOPCIProxy *proxy,
                                   unsigned int vector)
  {
      VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
-    return kvm_irqchip_add_irqfd_notifier_gsi(kvm_state, n, NULL, irqfd->virq);
+    return accel_irqchip_add_irqfd_notifier_gsi(n, NULL, irqfd->virq);
  }
static void kvm_virtio_pci_irqfd_release(VirtIOPCIProxy *proxy,
@@ -860,7 +861,7 @@ static void kvm_virtio_pci_irqfd_release(VirtIOPCIProxy 
*proxy,
      VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
      int ret;
- ret = kvm_irqchip_remove_irqfd_notifier_gsi(kvm_state, n, irqfd->virq);
+    ret = accel_irqchip_remove_irqfd_notifier_gsi(n, irqfd->virq);
      assert(ret == 0);
  }
  static int virtio_pci_get_notifier(VirtIOPCIProxy *proxy, int queue_no,
@@ -995,12 +996,12 @@ static int virtio_pci_one_vector_unmask(VirtIOPCIProxy 
*proxy,
      if (proxy->vector_irqfd) {
          irqfd = &proxy->vector_irqfd[vector];
          if (irqfd->msg.data != msg.data || irqfd->msg.address != msg.address) 
{
-            ret = kvm_irqchip_update_msi_route(kvm_state, irqfd->virq, msg,
-                                               &proxy->pci_dev);
+            ret = accel_irqchip_update_msi_route(irqfd->virq, msg,
+                                                 &proxy->pci_dev);
              if (ret < 0) {
                  return ret;
              }
-            kvm_irqchip_commit_routes(kvm_state);
+            accel_irqchip_commit_routes();
          }
      }
@@ -1229,7 +1230,7 @@ static int virtio_pci_set_guest_notifiers(DeviceState *d, int nvqs, bool assign)
      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
      int r, n;
      bool with_irqfd = msix_enabled(&proxy->pci_dev) &&
-        kvm_msi_via_irqfd_enabled();
+        accel_msi_via_irqfd_enabled() ;
nvqs = MIN(nvqs, VIRTIO_QUEUE_MAX); @@ -1433,7 +1434,7 @@ static void virtio_pci_set_vector(VirtIODevice *vdev,
                                    uint16_t new_vector)
  {
      bool kvm_irqfd = (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) &&
-        msix_enabled(&proxy->pci_dev) && kvm_msi_via_irqfd_enabled();
+        msix_enabled(&proxy->pci_dev) && accel_msi_via_irqfd_enabled();
if (new_vector == old_vector) {
          return;
diff --git a/accel/meson.build b/accel/meson.build
index 25b0f100b51..6349efe682f 100644
--- a/accel/meson.build
+++ b/accel/meson.build
@@ -1,6 +1,6 @@
  common_ss.add(files('accel-common.c'))
  specific_ss.add(files('accel-target.c'))
-system_ss.add(files('accel-system.c', 'accel-blocker.c', 'accel-qmp.c'))
+system_ss.add(files('accel-system.c', 'accel-blocker.c', 'accel-qmp.c', 
'accel-irq.c'))
  user_ss.add(files('accel-user.c'))
subdir('tcg')


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