[PATCH v1 3/8] vfio/type1: Report PASID alloc/free support to userspace

["Liu, Yi L" <yi.l.liu@xxxxxxxxx>]

From: Liu Yi L <yi.l.liu@xxxxxxxxx>

This patch reports PASID alloc/free availability to userspace (e.g. QEMU)
thus userspace could do a pre-check before utilizing this feature.

Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Eric Auger <eric.auger@xxxxxxxxxx>
Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
---
 drivers/vfio/vfio_iommu_type1.c | 28 ++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       |  8 ++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index e40afc0..ddd1ffe 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2234,6 +2234,30 @@ static int vfio_iommu_type1_pasid_free(struct vfio_iommu *iommu,
 	return ret;
 }
 
+static int vfio_iommu_info_add_nesting_cap(struct vfio_iommu *iommu,
+					 struct vfio_info_cap *caps)
+{
+	struct vfio_info_cap_header *header;
+	struct vfio_iommu_type1_info_cap_nesting *nesting_cap;
+
+	header = vfio_info_cap_add(caps, sizeof(*nesting_cap),
+				   VFIO_IOMMU_TYPE1_INFO_CAP_NESTING, 1);
+	if (IS_ERR(header))
+		return PTR_ERR(header);
+
+	nesting_cap = container_of(header,
+				struct vfio_iommu_type1_info_cap_nesting,
+				header);
+
+	nesting_cap->nesting_capabilities = 0;
+	if (iommu->nesting) {
+		/* nesting iommu type supports PASID requests (alloc/free) */
+		nesting_cap->nesting_capabilities |= VFIO_IOMMU_PASID_REQS;
+	}
+
+	return 0;
+}
+
 static long vfio_iommu_type1_ioctl(void *iommu_data,
 				   unsigned int cmd, unsigned long arg)
 {
@@ -2283,6 +2307,10 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 		if (ret)
 			return ret;
 
+		ret = vfio_iommu_info_add_nesting_cap(iommu, &caps);
+		if (ret)
+			return ret;
+
 		if (caps.size) {
 			info.flags |= VFIO_IOMMU_INFO_CAPS;
 
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 298ac80..8837219 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -748,6 +748,14 @@ struct vfio_iommu_type1_info_cap_iova_range {
 	struct	vfio_iova_range iova_ranges[];
 };
 
+#define VFIO_IOMMU_TYPE1_INFO_CAP_NESTING  2
+
+struct vfio_iommu_type1_info_cap_nesting {
+	struct	vfio_info_cap_header header;
+#define VFIO_IOMMU_PASID_REQS	(1 << 0)
+	__u32	nesting_capabilities;
+};
+
 #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
 
 /**
-- 
2.7.4