| Message ID | 4-v1-21cc72fcfb22+a7a-iommu_all_defdom_jgg@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iommu: Make default_domain's mandatory | expand |
On 2023-05-01 19:02, Jason Gunthorpe wrote: > It is not clear what this is actually doing, most likely this is IDENTITY > behavior, but I think there is a chance it is BLOCKING given how the PAMU > stuff is oddly used. Logically it has to be identity, since there are no DMA ops interacting with this driver (it's not the TCE IOMMU of arch/powerpc/kernel/iommu.c), so any device using a kernel driver rather than VFIO must be using dma-direct and thus require an identity mapping. At this point I finally got sufficiently fed up of this driver always being the mystery weirdo and tracked down an old QorIQ reference manual, and now I have about half an hours' worth of understanding of how the PAMU actually works. Based on that, what setup_liodns() is doing is indeed setting up identity for everything initially. It also becomes apparent that it's never supported giving a PCI device back to its regular driver after using vfio-pci, since an attach/detach cycle will then leave the PPAACE invalid and thus DMA blocked. Oh well, that's been broken for 10 years; nobody cares. Call it an identity domain and move on. Thanks, Robin. > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> > --- > drivers/iommu/fsl_pamu_domain.c | 29 ++++++++++++++++++++++++++--- > 1 file changed, 26 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c > index bce37229709965..4c65f1adfe7511 100644 > --- a/drivers/iommu/fsl_pamu_domain.c > +++ b/drivers/iommu/fsl_pamu_domain.c > @@ -283,15 +283,28 @@ static int fsl_pamu_attach_device(struct iommu_domain *domain, > return ret; > } > > -static void fsl_pamu_set_platform_dma(struct device *dev) > +/* > + * FIXME: This seems to turn off the iommu HW but it is not obvious what state > + * it leaves the HW in. This is probably really a BLOCKING or IDENTITY domain. > + * For now this ensures that the old detach_dev behavior functions about the > + * same as it always did, and we turn off the IOMMU whenever the UNMANAGED > + * domain is detached. > + */ > +static int fsl_pamu_platform_attach(struct iommu_domain *platform_domain, > + struct device *dev) > { > struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > - struct fsl_dma_domain *dma_domain = to_fsl_dma_domain(domain); > + struct fsl_dma_domain *dma_domain; > const u32 *prop; > int len; > struct pci_dev *pdev = NULL; > struct pci_controller *pci_ctl; > > + if (domain == platform_domain || !domain) > + return 0; > + > + dma_domain = to_fsl_dma_domain(domain); > + > /* > * Use LIODN of the PCI controller while detaching a > * PCI device. > @@ -312,8 +325,18 @@ static void fsl_pamu_set_platform_dma(struct device *dev) > detach_device(dev, dma_domain); > else > pr_debug("missing fsl,liodn property at %pOF\n", dev->of_node); > + return 0; > } > > +static struct iommu_domain_ops fsl_pamu_platform_ops = { > + .attach_dev = fsl_pamu_platform_attach, > +}; > + > +static struct iommu_domain fsl_pamu_platform_domain = { > + .type = IOMMU_DOMAIN_PLATFORM, > + .ops = &fsl_pamu_platform_ops, > +}; > + > /* Set the domain stash attribute */ > int fsl_pamu_configure_l1_stash(struct iommu_domain *domain, u32 cpu) > { > @@ -448,11 +471,11 @@ static struct iommu_device *fsl_pamu_probe_device(struct device *dev) > } > > static const struct iommu_ops fsl_pamu_ops = { > + .default_domain = &fsl_pamu_platform_domain, > .capable = fsl_pamu_capable, > .domain_alloc = fsl_pamu_domain_alloc, > .probe_device = fsl_pamu_probe_device, > .device_group = fsl_pamu_device_group, > - .set_platform_dma_ops = fsl_pamu_set_platform_dma, > .default_domain_ops = &(const struct iommu_domain_ops) { > .attach_dev = fsl_pamu_attach_device, > .iova_to_phys = fsl_pamu_iova_to_phys,
diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c index bce37229709965..4c65f1adfe7511 100644 --- a/drivers/iommu/fsl_pamu_domain.c +++ b/drivers/iommu/fsl_pamu_domain.c @@ -283,15 +283,28 @@ static int fsl_pamu_attach_device(struct iommu_domain *domain, return ret; } -static void fsl_pamu_set_platform_dma(struct device *dev) +/* + * FIXME: This seems to turn off the iommu HW but it is not obvious what state + * it leaves the HW in. This is probably really a BLOCKING or IDENTITY domain. + * For now this ensures that the old detach_dev behavior functions about the + * same as it always did, and we turn off the IOMMU whenever the UNMANAGED + * domain is detached. + */ +static int fsl_pamu_platform_attach(struct iommu_domain *platform_domain, + struct device *dev) { struct iommu_domain *domain = iommu_get_domain_for_dev(dev); - struct fsl_dma_domain *dma_domain = to_fsl_dma_domain(domain); + struct fsl_dma_domain *dma_domain; const u32 *prop; int len; struct pci_dev *pdev = NULL; struct pci_controller *pci_ctl; + if (domain == platform_domain || !domain) + return 0; + + dma_domain = to_fsl_dma_domain(domain); + /* * Use LIODN of the PCI controller while detaching a * PCI device. @@ -312,8 +325,18 @@ static void fsl_pamu_set_platform_dma(struct device *dev) detach_device(dev, dma_domain); else pr_debug("missing fsl,liodn property at %pOF\n", dev->of_node); + return 0; } +static struct iommu_domain_ops fsl_pamu_platform_ops = { + .attach_dev = fsl_pamu_platform_attach, +}; + +static struct iommu_domain fsl_pamu_platform_domain = { + .type = IOMMU_DOMAIN_PLATFORM, + .ops = &fsl_pamu_platform_ops, +}; + /* Set the domain stash attribute */ int fsl_pamu_configure_l1_stash(struct iommu_domain *domain, u32 cpu) { @@ -448,11 +471,11 @@ static struct iommu_device *fsl_pamu_probe_device(struct device *dev) } static const struct iommu_ops fsl_pamu_ops = { + .default_domain = &fsl_pamu_platform_domain, .capable = fsl_pamu_capable, .domain_alloc = fsl_pamu_domain_alloc, .probe_device = fsl_pamu_probe_device, .device_group = fsl_pamu_device_group, - .set_platform_dma_ops = fsl_pamu_set_platform_dma, .default_domain_ops = &(const struct iommu_domain_ops) { .attach_dev = fsl_pamu_attach_device, .iova_to_phys = fsl_pamu_iova_to_phys,
It is not clear what this is actually doing, most likely this is IDENTITY behavior, but I think there is a chance it is BLOCKING given how the PAMU stuff is oddly used. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> --- drivers/iommu/fsl_pamu_domain.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-)