[RFC PATCH 20/42] iommu/vt-d: Support attach devices to IOMMU_DOMAIN_KVM domain

[Yan Zhao <yan.y.zhao@xxxxxxxxx>]

IOMMU_DOMAIN_KVM domain reuses intel_iommu_attach_device() for device
attachment. But unlike attaching to other dmar_domain, domain caps (e.g.
iommu_superpage) are not updated after device attach. Instead, IOMMU caps
are checked for compatibility before domain attachment.

Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
---
 drivers/iommu/intel/iommu.c | 11 +++++++++++
 drivers/iommu/intel/iommu.h |  7 +++++++
 drivers/iommu/intel/kvm.c   |  9 +++++++++
 3 files changed, 27 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index fcdee40f30ed1..9cc42b3d24f65 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -552,6 +552,13 @@ static unsigned long domain_super_pgsize_bitmap(struct dmar_domain *domain)
 /* Some capabilities may be different across iommus */
 void domain_update_iommu_cap(struct dmar_domain *domain)
 {
+	/*
+	 * No need to adjust iommu cap of kvm domain.
+	 * Instead, iommu will be checked in pre-attach phase.
+	 */
+	if (domain_type_is_kvm(domain))
+		return;
+
 	domain_update_iommu_coherency(domain);
 	domain->iommu_superpage = domain_update_iommu_superpage(domain, NULL);
 
@@ -4104,6 +4111,9 @@ int prepare_domain_attach_device(struct iommu_domain *domain,
 	if (!iommu)
 		return -ENODEV;
 
+	if (domain_type_is_kvm(dmar_domain))
+		return prepare_kvm_domain_attach(dmar_domain, iommu);
+
 	if (dmar_domain->force_snooping && !ecap_sc_support(iommu->ecap))
 		return -EINVAL;
 
@@ -4117,6 +4127,7 @@ int prepare_domain_attach_device(struct iommu_domain *domain,
 
 	if (dmar_domain->max_addr > (1LL << addr_width))
 		return -EINVAL;
+
 	dmar_domain->gaw = addr_width;
 
 	/*
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 8826e9248f6ed..801700bc7d820 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1059,6 +1059,13 @@ static inline int width_to_agaw(int width)
 #ifdef CONFIG_INTEL_IOMMU_KVM
 struct iommu_domain *
 intel_iommu_domain_alloc_kvm(struct device *dev, u32 flags, const void *data);
+int prepare_kvm_domain_attach(struct dmar_domain *domain, struct intel_iommu *iommu);
+#else
+static inline int prepare_kvm_domain_attach(struct dmar_domain *domain,
+					    struct intel_iommu *iommu)
+{
+	return 0;
+}
 #endif
 
 #endif
diff --git a/drivers/iommu/intel/kvm.c b/drivers/iommu/intel/kvm.c
index 188ec90083051..1ce334785430b 100644
--- a/drivers/iommu/intel/kvm.c
+++ b/drivers/iommu/intel/kvm.c
@@ -32,6 +32,14 @@ static bool is_iommu_cap_compatible_to_kvm_domain(struct dmar_domain *domain,
 	return true;
 }
 
+int prepare_kvm_domain_attach(struct dmar_domain *domain, struct intel_iommu *iommu)
+{
+	if (is_iommu_cap_compatible_to_kvm_domain(domain, iommu))
+		return 0;
+
+	return -EINVAL;
+}
+
 /*
  * Cache coherency is always enforced in KVM domain.
  * IOMMU hardware caps will be checked to allow the cache coherency before
@@ -43,6 +51,7 @@ static bool kvm_domain_enforce_cache_coherency(struct iommu_domain *domain)
 }
 
 static const struct iommu_domain_ops intel_kvm_domain_ops = {
+	.attach_dev		= intel_iommu_attach_device,
 	.free			= intel_iommu_domain_free,
 	.enforce_cache_coherency = kvm_domain_enforce_cache_coherency,
 };
-- 
2.17.1