This patch adds the VFIO_IOMMU_SET_MSI_BINDING ioctl which aim
to (un)register the guest MSI binding to the host. This latter
then can use those stage 1 bindings to build a nested stage
binding targeting the physical MSIs.

Signed-off-by: Eric Auger <eric.au...@redhat.com>

---

v10 -> v11:
- renamed ustruct into msi_binding
- return 0 on unbind

v8 -> v9:
- merge VFIO_IOMMU_BIND_MSI/VFIO_IOMMU_UNBIND_MSI into a single
  VFIO_IOMMU_SET_MSI_BINDING ioctl
- ioctl id changed

v6 -> v7:
- removed the dev arg

v3 -> v4:
- add UNBIND
- unwind on BIND error

v2 -> v3:
- adapt to new proto of bind_guest_msi
- directly use vfio_iommu_for_each_dev

v1 -> v2:
- s/vfio_iommu_type1_guest_msi_binding/vfio_iommu_type1_bind_guest_msi
---
 drivers/vfio/vfio_iommu_type1.c | 63 +++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       | 20 +++++++++++
 2 files changed, 83 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 966909f542f1..bb2bc0971fb0 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2657,6 +2657,41 @@ static int vfio_cache_inv_fn(struct device *dev, void 
*data)
        return iommu_uapi_cache_invalidate(dc->domain, dev, (void __user *)arg);
 }
 
+static int
+vfio_bind_msi(struct vfio_iommu *iommu,
+             dma_addr_t giova, phys_addr_t gpa, size_t size)
+{
+       struct vfio_domain *d;
+       int ret = 0;
+
+       mutex_lock(&iommu->lock);
+
+       list_for_each_entry(d, &iommu->domain_list, next) {
+               ret = iommu_bind_guest_msi(d->domain, giova, gpa, size);
+               if (ret)
+                       goto unwind;
+       }
+       goto unlock;
+unwind:
+       list_for_each_entry_continue_reverse(d, &iommu->domain_list, next) {
+               iommu_unbind_guest_msi(d->domain, giova);
+       }
+unlock:
+       mutex_unlock(&iommu->lock);
+       return ret;
+}
+
+static void
+vfio_unbind_msi(struct vfio_iommu *iommu, dma_addr_t giova)
+{
+       struct vfio_domain *d;
+
+       mutex_lock(&iommu->lock);
+       list_for_each_entry(d, &iommu->domain_list, next)
+               iommu_unbind_guest_msi(d->domain, giova);
+       mutex_unlock(&iommu->lock);
+}
+
 static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,
                                           struct vfio_info_cap *caps)
 {
@@ -2866,6 +2901,32 @@ static int vfio_iommu_type1_cache_invalidate(struct 
vfio_iommu *iommu,
        return ret;
 }
 
+static int vfio_iommu_type1_set_msi_binding(struct vfio_iommu *iommu,
+                                           unsigned long arg)
+{
+       struct vfio_iommu_type1_set_msi_binding msi_binding;
+       unsigned long minsz;
+       int ret = -EINVAL;
+
+       minsz = offsetofend(struct vfio_iommu_type1_set_msi_binding,
+                           size);
+
+       if (copy_from_user(&msi_binding, (void __user *)arg, minsz))
+               return -EFAULT;
+
+       if (msi_binding.argsz < minsz)
+               return -EINVAL;
+
+       if (msi_binding.flags == VFIO_IOMMU_UNBIND_MSI) {
+               vfio_unbind_msi(iommu, msi_binding.iova);
+               ret = 0;
+       } else if (msi_binding.flags == VFIO_IOMMU_BIND_MSI) {
+               ret = vfio_bind_msi(iommu, msi_binding.iova,
+                                   msi_binding.gpa, msi_binding.size);
+       }
+       return ret;
+}
+
 static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
                                        unsigned long arg)
 {
@@ -2990,6 +3051,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
                return vfio_iommu_type1_set_pasid_table(iommu, arg);
        case VFIO_IOMMU_CACHE_INVALIDATE:
                return vfio_iommu_type1_cache_invalidate(iommu, arg);
+       case VFIO_IOMMU_SET_MSI_BINDING:
+               return vfio_iommu_type1_set_msi_binding(iommu, arg);
        default:
                return -ENOTTY;
        }
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 0e6d94cc2ba4..b352e76cfb71 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1212,6 +1212,26 @@ struct vfio_iommu_type1_cache_invalidate {
 };
 #define VFIO_IOMMU_CACHE_INVALIDATE      _IO(VFIO_TYPE, VFIO_BASE + 23)
 
+/**
+ * VFIO_IOMMU_SET_MSI_BINDING - _IOWR(VFIO_TYPE, VFIO_BASE + 24,
+ *                     struct vfio_iommu_type1_set_msi_binding)
+ *
+ * Pass a stage 1 MSI doorbell mapping to the host so that this
+ * latter can build a nested stage2 mapping. Or conversely tear
+ * down a previously bound stage 1 MSI binding.
+ */
+struct vfio_iommu_type1_set_msi_binding {
+       __u32   argsz;
+       __u32   flags;
+#define VFIO_IOMMU_BIND_MSI    (1 << 0)
+#define VFIO_IOMMU_UNBIND_MSI  (1 << 1)
+       __u64   iova;   /* MSI guest IOVA */
+       /* Fields below are used on BIND */
+       __u64   gpa;    /* MSI guest physical address */
+       __u64   size;   /* size of stage1 mapping (bytes) */
+};
+#define VFIO_IOMMU_SET_MSI_BINDING      _IO(VFIO_TYPE, VFIO_BASE + 24)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.21.3

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