[RFC][PATCH v2 06/13] vfio/type1: Set/get VMID to/from iommu driver

[Nicolin Chen <nicolinc@nvidia.com>]

This patch adds a pair of callbacks of iommu_set_nesting_vmid() and
iommu_get_nesting_vmid() to exchange VMID with the IOMMU core (then
an IOMMU driver).

As a VMID is generated in an IOMMU driver, which is called from the
vfio_iommu_attach_group() function call, add iommu_get_nesting_vmid
right after it creates a VMID and add iommu_set_nesting_vmid before
it to let IOMMU driver reuse it.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index bb5d949bc1af..9e72d74dedcd 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2322,12 +2322,24 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		ret = iommu_enable_nesting(domain->domain);
 		if (ret)
 			goto out_domain;
+
+		if (iommu->vmid != VFIO_IOMMU_VMID_INVALID) {
+			ret = iommu_set_nesting_vmid(domain->domain, iommu->vmid);
+			if (ret)
+				goto out_domain;
+		}
 	}
 
 	ret = vfio_iommu_attach_group(domain, group);
 	if (ret)
 		goto out_domain;
 
+	if (iommu->nesting && iommu->vmid == VFIO_IOMMU_VMID_INVALID) {
+		ret = iommu_get_nesting_vmid(domain->domain, &iommu->vmid);
+		if (ret)
+			goto out_domain;
+	}
+
 	/* Get aperture info */
 	geo = &domain->domain->geometry;
 	if (vfio_iommu_aper_conflict(iommu, geo->aperture_start,
-- 
2.17.1