[PATCH v2 15/23] vfio-user: forward msix BAR accesses to server

[John Johnson]

Server holds device current device pending state
Use irq masking commands in socket case

Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
---
 hw/vfio/pci.h                 |  1 +
 include/hw/vfio/vfio-common.h |  3 ++
 hw/vfio/ccw.c                 |  1 +
 hw/vfio/common.c              | 26 ++++++++++++++++++
 hw/vfio/pci.c                 | 23 +++++++++++++++-
 hw/vfio/platform.c            |  1 +
 hw/vfio/user-pci.c            | 64 +++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 118 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 4f70664..d3e5d5f 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -113,6 +113,7 @@ typedef struct VFIOMSIXInfo {
     uint32_t table_offset;
     uint32_t pba_offset;
     unsigned long *pending;
+    MemoryRegion *pba_region;
 } VFIOMSIXInfo;
 
 /*
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index bbc4b15..2c58d7d 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -143,6 +143,7 @@ typedef struct VFIODevice {
     bool ram_block_discard_allowed;
     bool enable_migration;
     bool use_regfds;
+    bool can_mask_irq;
     VFIODeviceOps *ops;
     VFIODeviceIO *io;
     unsigned int num_irqs;
@@ -239,6 +240,8 @@ void vfio_put_base_device(VFIODevice *vbasedev);
 void vfio_disable_irqindex(VFIODevice *vbasedev, int index);
 void vfio_unmask_single_irqindex(VFIODevice *vbasedev, int index);
 void vfio_mask_single_irqindex(VFIODevice *vbasedev, int index);
+void vfio_unmask_single_irq(VFIODevice *vbasedev, int index, int irq);
+void vfio_mask_single_irq(VFIODevice *vbasedev, int index, int irq);
 int vfio_set_irq_signaling(VFIODevice *vbasedev, int index, int subindex,
                            int action, int fd, Error **errp);
 void vfio_region_write(void *opaque, hwaddr addr,
diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
index 00605bd..bf67670 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -616,6 +616,7 @@ static void vfio_ccw_get_device(VFIOGroup *group, 
VFIOCCWDevice *vcdev,
     vcdev->vdev.dev = &vcdev->cdev.parent_obj.parent_obj;
     vcdev->vdev.io = &vfio_dev_io_ioctl;
     vcdev->vdev.use_regfds = false;
+    vcdev->vdev.can_mask_irq = false;
 
     return;
 
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index de64e53..0c1cb21 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -102,6 +102,32 @@ void vfio_mask_single_irqindex(VFIODevice *vbasedev, int 
index)
     vbasedev->io->set_irqs(vbasedev, &irq_set);
 }
 
+void vfio_mask_single_irq(VFIODevice *vbasedev, int index, int irq)
+{
+    struct vfio_irq_set irq_set = {
+        .argsz = sizeof(irq_set),
+        .flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_MASK,
+        .index = index,
+        .start = irq,
+        .count = 1,
+    };
+
+    vbasedev->io->set_irqs(vbasedev, &irq_set);
+}
+
+void vfio_unmask_single_irq(VFIODevice *vbasedev, int index, int irq)
+{
+    struct vfio_irq_set irq_set = {
+        .argsz = sizeof(irq_set),
+        .flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_UNMASK,
+        .index = index,
+        .start = irq,
+        .count = 1,
+    };
+
+    vbasedev->io->set_irqs(vbasedev, &irq_set);
+}
+
 static inline const char *action_to_str(int action)
 {
     switch (action) {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 42e7c82..7b16f8f 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -477,6 +477,7 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
 {
     VFIOPCIDevice *vdev = VFIO_PCI_BASE(pdev);
     VFIOMSIVector *vector;
+    bool new_vec = false;
     int ret;
 
     trace_vfio_msix_vector_do_use(vdev->vbasedev.name, nr);
@@ -490,6 +491,7 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
             error_report("vfio: Error: event_notifier_init failed");
         }
         vector->use = true;
+        new_vec = true;
         msix_vector_use(pdev, nr);
     }
 
@@ -516,6 +518,7 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
                 kvm_irqchip_commit_route_changes(&vfio_route_change);
                 vfio_connect_kvm_msi_virq(vector);
             }
+            new_vec = true;
         }
     }
 
@@ -523,6 +526,8 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
      * We don't want to have the host allocate all possible MSI vectors
      * for a device if they're not in use, so we shutdown and incrementally
      * increase them as needed.
+     * Otherwise, unmask the vector if the vector is already setup (and we can
+     * do so) or send the fd if not.
      */
     if (vdev->nr_vectors < nr + 1) {
         vdev->nr_vectors = nr + 1;
@@ -533,6 +538,8 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, 
unsigned int nr,
                 error_report("vfio: failed to enable vectors, %d", ret);
             }
         }
+    } else if (vdev->vbasedev.can_mask_irq && !new_vec) {
+        vfio_unmask_single_irq(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX, nr);
     } else {
         Error *err = NULL;
         int32_t fd;
@@ -574,6 +581,12 @@ static void vfio_msix_vector_release(PCIDevice *pdev, 
unsigned int nr)
 
     trace_vfio_msix_vector_release(vdev->vbasedev.name, nr);
 
+    /* just mask vector if peer supports it */
+    if (vdev->vbasedev.can_mask_irq) {
+        vfio_mask_single_irq(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX, nr);
+        return;
+    }
+
     /*
      * There are still old guests that mask and unmask vectors on every
      * interrupt.  If we're using QEMU bypass with a KVM irqfd, leave all of
@@ -644,7 +657,7 @@ static void vfio_msix_enable(VFIOPCIDevice *vdev)
         if (ret) {
             error_report("vfio: failed to enable vectors, %d", ret);
         }
-    } else {
+    } else if (!vdev->vbasedev.can_mask_irq) {
         /*
          * Some communication channels between VF & PF or PF & fw rely on the
          * physical state of the device and expect that enabling MSI-X from the
@@ -660,6 +673,13 @@ static void vfio_msix_enable(VFIOPCIDevice *vdev)
          */
         vfio_msix_vector_do_use(&vdev->pdev, 0, NULL, NULL);
         vfio_msix_vector_release(&vdev->pdev, 0);
+    } else {
+        /*
+         * If we can use irq masking, send an invalid fd on vector 0
+         * to enable MSI-X without any vectors enabled.
+         */
+        vfio_set_irq_signaling(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX, 0,
+                               VFIO_IRQ_SET_ACTION_TRIGGER, -1, NULL);
     }
 
     trace_vfio_msix_enable(vdev->vbasedev.name);
@@ -3040,6 +3060,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     vbasedev->dev = DEVICE(vdev);
     vbasedev->io = &vfio_dev_io_ioctl;
     vbasedev->use_regfds = false;
+    vbasedev->can_mask_irq = false;
 
     tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev);
     len = readlink(tmp, group_path, sizeof(group_path));
diff --git a/hw/vfio/platform.c b/hw/vfio/platform.c
index 8ddfcca..3387ec4 100644
--- a/hw/vfio/platform.c
+++ b/hw/vfio/platform.c
@@ -623,6 +623,7 @@ static void vfio_platform_realize(DeviceState *dev, Error 
**errp)
     vbasedev->ops = &vfio_platform_ops;
     vbasedev->io = &vfio_dev_io_ioctl;
     vbasedev->use_regfds = false;
+    vbasedev->can_mask_irq = false;
 
     qemu_mutex_init(&vdev->intp_mutex);
 
diff --git a/hw/vfio/user-pci.c b/hw/vfio/user-pci.c
index 55ffe7f..bc1d01a 100644
--- a/hw/vfio/user-pci.c
+++ b/hw/vfio/user-pci.c
@@ -45,6 +45,62 @@ struct VFIOUserPCIDevice {
 };
 
 /*
+ * The server maintains the device's pending interrupts,
+ * via its MSIX table and PBA, so we treat these acceses
+ * like PCI config space and forward them.
+ */
+static uint64_t vfio_user_pba_read(void *opaque, hwaddr addr,
+                                   unsigned size)
+{
+    VFIOPCIDevice *vdev = opaque;
+    VFIORegion *region = &vdev->bars[vdev->msix->pba_bar].region;
+    uint64_t data;
+
+    /* server copy is what matters */
+    data = vfio_region_read(region, addr + vdev->msix->pba_offset, size);
+    return data;
+}
+
+static void vfio_user_pba_write(void *opaque, hwaddr addr,
+                                  uint64_t data, unsigned size)
+{
+    /* dropped */
+}
+
+static const MemoryRegionOps vfio_user_pba_ops = {
+    .read = vfio_user_pba_read,
+    .write = vfio_user_pba_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static void vfio_user_msix_setup(VFIOPCIDevice *vdev)
+{
+    MemoryRegion *vfio_reg, *msix_reg, *pba_reg;
+
+    pba_reg = g_new0(MemoryRegion, 1);
+    vdev->msix->pba_region = pba_reg;
+
+    vfio_reg = vdev->bars[vdev->msix->pba_bar].mr;
+    msix_reg = &vdev->pdev.msix_pba_mmio;
+    memory_region_init_io(pba_reg, OBJECT(vdev), &vfio_user_pba_ops, vdev,
+                          "VFIO MSIX PBA", int128_get64(msix_reg->size));
+    memory_region_add_subregion_overlap(vfio_reg, vdev->msix->pba_offset,
+                                        pba_reg, 1);
+}
+
+static void vfio_user_msix_teardown(VFIOPCIDevice *vdev)
+{
+    MemoryRegion *mr, *sub;
+
+    mr = vdev->bars[vdev->msix->pba_bar].mr;
+    sub = vdev->msix->pba_region;
+    memory_region_del_subregion(mr, sub);
+
+    g_free(vdev->msix->pba_region);
+    vdev->msix->pba_region = NULL;
+}
+
+/*
  * Incoming request message callback.
  *
  * Runs off main loop, so BQL held.
@@ -122,6 +178,7 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error 
**errp)
     vbasedev->dev = DEVICE(vdev);
     vbasedev->io = &vfio_dev_io_sock;
     vbasedev->use_regfds = true;
+    vbasedev->can_mask_irq = true;
 
     ret = vfio_user_get_device(vbasedev, errp);
     if (ret) {
@@ -159,6 +216,9 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error 
**errp)
     if (ret) {
         goto out_teardown;
     }
+    if (vdev->msix != NULL) {
+        vfio_user_msix_setup(vdev);
+    }
 
     ret = vfio_interrupt_setup(vdev, errp);
     if (ret) {
@@ -186,6 +246,10 @@ static void vfio_user_instance_finalize(Object *obj)
     g_free(vdev->emulated_config_bits);
     g_free(vdev->rom);
 
+    if (vdev->msix != NULL) {
+        vfio_user_msix_teardown(vdev);
+    }
+
     vfio_put_device(vdev);
 
     if (vbasedev->proxy != NULL) {
-- 
1.9.4