Messages in this thread Patch in this message | | | Date | Thu, 16 Mar 2023 18:42:07 +0000 | Subject | Re: [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain helper | From | Robin Murphy <> |
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On 16/03/2023 1:21 am, Nicolin Chen wrote: > Hi Robin, > > How do you think about Jason's proposal below? I'd like to see > us come to an agreement on an acceptable solution...
I think it's so thoroughly broken that I suspect Cunningham's law might be at play, but fine, you win :) Hopefully it's sufficiently obvious how the other pieces would fit around the patch below. FWIW I'd still prefer a generic domain->s2_domain pointer rather than any op at all, but I'm happy enough with this compromise.
Thanks, Robin.
----->8----- Subject: [PATCH] iommu/dma: Support MSIs through nested domains
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 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> --- drivers/iommu/dma-iommu.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 99b2646cb5c7..66b0d5fa49f8 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1642,6 +1642,20 @@ 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) + 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 @@ -1652,7 +1666,7 @@ 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 */ @@ -1685,7 +1699,7 @@ 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); -- 2.39.2.101.g768bb238c484.dirty
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