From: Nicolin Chen nicolinc@nvidia.com Sent: Saturday, August 3, 2024 8:32 AM
From: Robin Murphy robin.murphy@arm.com
Currently, iommu-dma is the only place outside of IOMMUFD and drivers which might need to be aware of the stage 2 domain encapsulated within a nested domain. This would be in the legacy-VFIO-style case where we're
why is it a legacy-VFIO-style? We only support nested in IOMMUFD.
using host-managed MSIs with an identity mapping at stage 1, where it is the underlying stage 2 domain which owns an MSI cookie and holds the corresponding dynamic mappings. Hook up the new op to resolve what we need from a nested domain.
Signed-off-by: Robin Murphy robin.murphy@arm.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com
drivers/iommu/dma-iommu.c | 18 ++++++++++++++++-- include/linux/iommu.h | 4 ++++ 2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 7b1dfa0665df6..05e04934a5f81 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1799,6 +1799,20 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev, return NULL; }
+/*
- Nested domains may not have an MSI cookie or accept mappings, but
they may
- be related to a domain which does, so we let them tell us what they need.
- */
+static struct iommu_domain *iommu_dma_get_msi_mapping_domain(struct device *dev) +{
- struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
- if (domain && domain->type == IOMMU_DOMAIN_NESTED &&
domain->ops->get_msi_mapping_domain)
I'm not sure the core should restrict it to the NESTED type. Given there is a new domain ops any type restriction can be handled inside the callback. Anyway the driver should register the op for a domain only when there is a need.
domain = domain->ops->get_msi_mapping_domain(domain);- return domain;
+}
/**
- iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain
- @desc: MSI descriptor, will store the MSI page
@@ -1809,7 +1823,7 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev, int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr) { struct device *dev = msi_desc_to_dev(desc);
- struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
- struct iommu_domain *domain =
iommu_dma_get_msi_mapping_domain(dev); struct iommu_dma_msi_page *msi_page; static DEFINE_MUTEX(msi_prepare_lock); /* see below */
@@ -1842,7 +1856,7 @@ int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr) void iommu_dma_compose_msi_msg(struct msi_desc *desc, struct msi_msg *msg) { struct device *dev = msi_desc_to_dev(desc);
- const struct iommu_domain *domain =
iommu_get_domain_for_dev(dev);
- const struct iommu_domain *domain =
iommu_dma_get_msi_mapping_domain(dev); const struct iommu_dma_msi_page *msi_page;
msi_page = msi_desc_get_iommu_cookie(desc); diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 4d47f2c333118..69ed76f9c3ec4 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -638,6 +638,8 @@ struct iommu_ops {
- @enable_nesting: Enable nesting
- @set_pgtable_quirks: Set io page table quirks (IO_PGTABLE_QUIRK_*)
- @free: Release the domain after use.
- @get_msi_mapping_domain: Return the related iommu_domain that
should hold the
*/
MSI cookie and accept mapping(s).struct iommu_domain_ops { int (*attach_dev)(struct iommu_domain *domain, struct device *dev); @@ -668,6 +670,8 @@ struct iommu_domain_ops { unsigned long quirks);
void (*free)(struct iommu_domain *domain);
- struct iommu_domain *
(*get_msi_mapping_domain)(struct iommu_domain*domain); };
/**
2.43.0