linux-kernel - [PATCH v4 15/32] vfio: introduce KVM-owned IOMMU type

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Date:   Mon, 14 Mar 2022 15:44:34 -0400
From:   Matthew Rosato <mjrosato@...ux.ibm.com>
To:     linux-s390@...r.kernel.org
Cc:     alex.williamson@...hat.com, cohuck@...hat.com,
        schnelle@...ux.ibm.com, farman@...ux.ibm.com, pmorel@...ux.ibm.com,
        borntraeger@...ux.ibm.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        imbrenda@...ux.ibm.com, vneethv@...ux.ibm.com,
        oberpar@...ux.ibm.com, freude@...ux.ibm.com, thuth@...hat.com,
        pasic@...ux.ibm.com, joro@...tes.org, will@...nel.org,
        pbonzini@...hat.com, corbet@....net, jgg@...dia.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-doc@...r.kernel.org
Subject: [PATCH v4 15/32] vfio: introduce KVM-owned IOMMU type

s390x will introduce a new IOMMU domain type where the mappings are
managed by KVM rather than in response to userspace mapping ioctls.  Allow
for specifying this type on the VFIO_SET_IOMMU ioctl and triggering the
appropriate iommu interface for overriding the default domain.

Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
---
 drivers/vfio/vfio_iommu_type1.c | 12 +++++++++++-
 include/uapi/linux/vfio.h       |  6 ++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 9394aa9444c1..0bec97077d61 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -77,6 +77,7 @@ struct vfio_iommu {
 	bool			nesting;
 	bool			dirty_page_tracking;
 	bool			container_open;
+	bool			kvm;
 	struct list_head	emulated_iommu_groups;
 };
 
@@ -2203,7 +2204,12 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_free_group;
 
 	ret = -EIO;
-	domain->domain = iommu_domain_alloc(bus);
+
+	if (iommu->kvm)
+		domain->domain = iommu_domain_alloc_type(bus, IOMMU_DOMAIN_KVM);
+	else
+		domain->domain = iommu_domain_alloc(bus);
+
 	if (!domain->domain)
 		goto out_free_domain;
 
@@ -2552,6 +2558,9 @@ static void *vfio_iommu_type1_open(unsigned long arg)
 	case VFIO_TYPE1v2_IOMMU:
 		iommu->v2 = true;
 		break;
+	case VFIO_KVM_IOMMU:
+		iommu->kvm = true;
+		break;
 	default:
 		kfree(iommu);
 		return ERR_PTR(-EINVAL);
@@ -2637,6 +2646,7 @@ static int vfio_iommu_type1_check_extension(struct vfio_iommu *iommu,
 	case VFIO_TYPE1_NESTING_IOMMU:
 	case VFIO_UNMAP_ALL:
 	case VFIO_UPDATE_VADDR:
+	case VFIO_KVM_IOMMU:
 		return 1;
 	case VFIO_DMA_CC_IOMMU:
 		if (!iommu)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index ef33ea002b0b..666edb6957ac 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -52,6 +52,12 @@
 /* Supports the vaddr flag for DMA map and unmap */
 #define VFIO_UPDATE_VADDR		10
 
+/*
+ * The KVM_IOMMU type implies that the hypervisor will control the mappings
+ * rather than userspace
+ */
+#define VFIO_KVM_IOMMU			11
+
 /*
  * The IOCTL interface is designed for extensibility by embedding the
  * structure length (argsz) and flags into structures passed between
-- 
2.27.0