[PATCH v4 4/7] iommu/riscv: Enable IOMMU registration and device probe.

[Tomasz Jeznach]

On Mon, May 13, 2024 at 10:56 PM Zong Li <zong.li at sifive.com> wrote:
>
> On Sat, May 4, 2024 at 12:13 AM Tomasz Jeznach <tjeznach at rivosinc.com> wrote:
> >
> > Advertise IOMMU device and its core API.
> > Only minimal implementation for single identity domain type, without
> > per-group domain protection.
> >
> > Reviewed-by: Lu Baolu <baolu.lu at linux.intel.com>
> > Signed-off-by: Tomasz Jeznach <tjeznach at rivosinc.com>
> > ---
> >  drivers/iommu/riscv/iommu.c | 66 +++++++++++++++++++++++++++++++++++++
> >  1 file changed, 66 insertions(+)
> >
> > diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
> > index 3c5a6b49669d..1f889daffb0e 100644
> > --- a/drivers/iommu/riscv/iommu.c
> > +++ b/drivers/iommu/riscv/iommu.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/init.h>
> >  #include <linux/iommu.h>
> >  #include <linux/kernel.h>
> > +#include <linux/pci.h>
> >
> >  #include "iommu-bits.h"
> >  #include "iommu.h"
> > @@ -36,6 +37,60 @@ static void riscv_iommu_disable(struct riscv_iommu_device *iommu)
> >         riscv_iommu_writel(iommu, RISCV_IOMMU_REG_PQCSR, 0);
> >  }
> >
> > +static int riscv_iommu_attach_identity_domain(struct iommu_domain *iommu_domain,
> > +                                             struct device *dev)
> > +{
> > +       /* Global pass-through already enabled, do nothing for now. */
> > +       return 0;
> > +}
> > +
> > +static struct iommu_domain riscv_iommu_identity_domain = {
> > +       .type = IOMMU_DOMAIN_IDENTITY,
> > +       .ops = &(const struct iommu_domain_ops) {
> > +               .attach_dev = riscv_iommu_attach_identity_domain,
> > +       }
> > +};
> > +
> > +static int riscv_iommu_device_domain_type(struct device *dev)
> > +{
> > +       return IOMMU_DOMAIN_IDENTITY;
> > +}
> > +
> > +static struct iommu_group *riscv_iommu_device_group(struct device *dev)
> > +{
> > +       if (dev_is_pci(dev))
> > +               return pci_device_group(dev);
> > +       return generic_device_group(dev);
> > +}
> > +
> > +static int riscv_iommu_of_xlate(struct device *dev, const struct of_phandle_args *args)
> > +{
> > +       return iommu_fwspec_add_ids(dev, args->args, 1);
> > +}
> > +
> > +static struct iommu_device *riscv_iommu_probe_device(struct device *dev)
> > +{
> > +       struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> > +       struct riscv_iommu_device *iommu;
> > +
> > +       if (!fwspec->iommu_fwnode->dev || !fwspec->num_ids)
> > +               return ERR_PTR(-ENODEV);
>
> It seems to me that we might need to ensure fwspec is not NULL before
> accessing fwspec->iommu_fwnode, otherwise, it will cause NULL pointer
> dereference.
>

Thank you. Fix applied to v5.

> > +
> > +       iommu = dev_get_drvdata(fwspec->iommu_fwnode->dev);
> > +       if (!iommu)
> > +               return ERR_PTR(-ENODEV);
> > +
> > +       return &iommu->iommu;
> > +}
> > +
> > +static const struct iommu_ops riscv_iommu_ops = {
> > +       .of_xlate = riscv_iommu_of_xlate,
> > +       .identity_domain = &riscv_iommu_identity_domain,
> > +       .def_domain_type = riscv_iommu_device_domain_type,
> > +       .device_group = riscv_iommu_device_group,
> > +       .probe_device = riscv_iommu_probe_device,
> > +};
> > +
> >  static int riscv_iommu_init_check(struct riscv_iommu_device *iommu)
> >  {
> >         u64 ddtp;
> > @@ -71,6 +126,7 @@ static int riscv_iommu_init_check(struct riscv_iommu_device *iommu)
> >
> >  void riscv_iommu_remove(struct riscv_iommu_device *iommu)
> >  {
> > +       iommu_device_unregister(&iommu->iommu);
> >         iommu_device_sysfs_remove(&iommu->iommu);
> >  }
> >
> > @@ -95,5 +151,15 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
> >                 return dev_err_probe(iommu->dev, rc,
> >                                      "cannot register sysfs interface\n");
> >
> > +       rc = iommu_device_register(&iommu->iommu, &riscv_iommu_ops, iommu->dev);
> > +       if (rc) {
> > +               dev_err_probe(iommu->dev, rc, "cannot register iommu interface\n");
> > +               goto err_remove_sysfs;
> > +       }
> > +
> >         return 0;
> > +
> > +err_remove_sysfs:
> > +       iommu_device_sysfs_remove(&iommu->iommu);
> > +       return rc;
> >  }
> > --
> > 2.34.1
> >
> >

Best,
- Tomasz

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