Messages in this thread Patch in this message | | | Date | Thu, 16 Mar 2023 13:01:33 -0700 | From | Nicolin Chen <> | Subject | Re: [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain helper |
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On Thu, Mar 16, 2023 at 06:42:07PM +0000, Robin Murphy wrote: > External email: Use caution opening links or attachments > > > 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.
Oh, I appreciate that! Looks like we can move on with a v2 :)
I will include this patch replacing mine in the next version.
Thanks! Nic
> ----->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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