Re: [PATCH 01/11] RISC-V: drivers/iommu: Add RISC-V IOMMU - Ziommu support.

From: Zong Li
Date: Wed Aug 02 2023 - 23:37:32 EST


On Thu, Aug 3, 2023 at 4:15 AM Tomasz Jeznach <tjeznach@xxxxxxxxxxxx> wrote:
>
> On Thu, Jul 27, 2023 at 7:42 PM Zong Li <zong.li@xxxxxxxxxx> wrote:
> >
> > On Thu, Jul 20, 2023 at 3:34 AM Tomasz Jeznach <tjeznach@xxxxxxxxxxxx> wrote:
> > >
> > > +static int riscv_iommu_platform_probe(struct platform_device *pdev)
> > > +{
> > > + struct device *dev = &pdev->dev;
> > > + struct riscv_iommu_device *iommu = NULL;
> > > + struct resource *res = NULL;
> > > + int ret = 0;
> > > +
> > > + iommu = devm_kzalloc(dev, sizeof(*iommu), GFP_KERNEL);
> > > + if (!iommu)
> > > + return -ENOMEM;
> > > +
> > > + iommu->dev = dev;
> > > + dev_set_drvdata(dev, iommu);
> > > +
> > > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > + if (!res) {
> > > + dev_err(dev, "could not find resource for register region\n");
> > > + return -EINVAL;
> > > + }
> > > +
> > > + iommu->reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> > > + if (IS_ERR(iommu->reg)) {
> > > + ret = dev_err_probe(dev, PTR_ERR(iommu->reg),
> > > + "could not map register region\n");
> > > + goto fail;
> > > + };
> > > +
> > > + iommu->reg_phys = res->start;
> > > +
> > > + ret = -ENODEV;
> > > +
> > > + /* Sanity check: Did we get the whole register space ? */
> > > + if ((res->end - res->start + 1) < RISCV_IOMMU_REG_SIZE) {
> > > + dev_err(dev, "device region smaller than register file (0x%llx)\n",
> > > + res->end - res->start);
> > > + goto fail;
> > > + }
> >
> > Could we assume that DT should be responsible for specifying the right size?
> >
>
> This only to validate DT provided info and driver expected register
> file size. Expectation is that DT will provide right size.
>
>
> > > +static struct iommu_domain *riscv_iommu_domain_alloc(unsigned type)
> > > +{
> > > + struct riscv_iommu_domain *domain;
> > > +
> > > + if (type != IOMMU_DOMAIN_IDENTITY &&
> > > + type != IOMMU_DOMAIN_BLOCKED)
> > > + return NULL;
> > > +
> > > + domain = kzalloc(sizeof(*domain), GFP_KERNEL);
> > > + if (!domain)
> > > + return NULL;
> > > +
> > > + mutex_init(&domain->lock);
> > > + INIT_LIST_HEAD(&domain->endpoints);
> > > +
> > > + domain->domain.ops = &riscv_iommu_domain_ops;
> > > + domain->mode = RISCV_IOMMU_DC_FSC_MODE_BARE;
> > > + domain->pscid = ida_alloc_range(&riscv_iommu_pscids, 1,
> > > + RISCV_IOMMU_MAX_PSCID, GFP_KERNEL);
> > > +
> > > + printk("domain type %x alloc %u\n", type, domain->pscid);
> > > +
> >
> > Could it uses pr_xxx instead of printk?
> >
>
> Absolutely, fixed here and elsewhere. Also, used dev_dbg wherever applicable.
>
> > > +
> > > +static int riscv_iommu_enable(struct riscv_iommu_device *iommu, unsigned requested_mode)
> > > +{
> > > + struct device *dev = iommu->dev;
> > > + u64 ddtp = 0;
> > > + u64 ddtp_paddr = 0;
> > > + unsigned mode = requested_mode;
> > > + unsigned mode_readback = 0;
> > > +
> > > + ddtp = riscv_iommu_get_ddtp(iommu);
> > > + if (ddtp & RISCV_IOMMU_DDTP_BUSY)
> > > + return -EBUSY;
> > > +
> > > + /* Disallow state transtion from xLVL to xLVL. */
> > > + switch (FIELD_GET(RISCV_IOMMU_DDTP_MODE, ddtp)) {
> > > + case RISCV_IOMMU_DDTP_MODE_BARE:
> > > + case RISCV_IOMMU_DDTP_MODE_OFF:
> > > + break;
> > > + default:
> > > + if ((mode != RISCV_IOMMU_DDTP_MODE_BARE)
> > > + && (mode != RISCV_IOMMU_DDTP_MODE_OFF))
> > > + return -EINVAL;
> > > + break;
> > > + }
> > > +
> > > + retry:
> >
> > We need to consider the `iommu.passthrough` before we set up the mode
> > in switch case, something like
> >
>
> This function is only to execute configuration and set device directory mode.
> Handling global iommu.passthrough policy is implemented in
> riscv_iommu_init() call (patch #7).

Thanks. I saw that in patch #7.

>
> Best,
> - Tomasz