On Wed, May 1, 2024 at 8:52 PM Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> wrote:
>
> On 5/1/24 4:01 AM, Tomasz Jeznach wrote:
> > +/*
> > + * Send IOTLB.INVAL for whole address space for ranges larger than 2MB.
> > + * This limit will be replaced with range invalidations, if supported by
> > + * the hardware, when RISC-V IOMMU architecture specification update for
> > + * range invalidations update will be available.
> > + */
> > +#define RISCV_IOMMU_IOTLB_INVAL_LIMIT (2 << 20)
> > +
> > +static void riscv_iommu_iotlb_inval(struct riscv_iommu_domain *domain,
> > + unsigned long start, unsigned long end)
> > +{
> > + struct riscv_iommu_bond *bond;
> > + struct riscv_iommu_device *iommu, *prev;
> > + struct riscv_iommu_command cmd;
> > + unsigned long len = end - start + 1;
> > + unsigned long iova;
> > +
> > + rcu_read_lock();
> > +
> > + prev = NULL;
> > + list_for_each_entry_rcu(bond, &domain->bonds, list) {
> > + iommu = dev_to_iommu(bond->dev);
> > +
> > + riscv_iommu_cmd_inval_vma(&cmd);
> > + riscv_iommu_cmd_inval_set_pscid(&cmd, domain->pscid);
> > + if (len && len >= RISCV_IOMMU_IOTLB_INVAL_LIMIT) {
> > + for (iova = start; iova < end; iova += PAGE_SIZE) {
> > + riscv_iommu_cmd_inval_set_addr(&cmd, iova);
> > + riscv_iommu_cmd_send(iommu, &cmd, 0);
> > + }
> > + } else {
> > + riscv_iommu_cmd_send(iommu, &cmd, 0);
> > + }
> > +
> > + /*
> > + * IOTLB invalidation request can be safely omitted if already sent
> > + * to the IOMMU for the same PSCID, and with domain->bonds list
> > + * arranged based on the device's IOMMU, it's sufficient to check
> > + * last device the invalidation was sent to.
> > + */
> > + if (iommu == prev)
> > + continue;
> > +
> > + prev = iommu;
> > + riscv_iommu_cmd_send(iommu, &cmd, 0);
> > + }
>
> I don't quite follow why not moving "if (iommu == prev)" check to the
> top and removing the last riscv_iommu_cmd_send(). My understanding is
> that we could make it simply like below:
>
> prev = NULL;
> list_for_each_entry_rcu(bond, &domain->bonds, list) {
> iommu = dev_to_iommu(bond->dev);
> if (iommu == prev)
> continue;
>
> /*
> * Send an invalidation request to the request queue
> * without wait.
> */
> ... ...
>
> prev = iommu;
> }
>
Oh. Thanks for spotting that.
Code section reordered very likely during rebasing patches...
> > +
> > + prev = NULL;
> > + list_for_each_entry_rcu(bond, &domain->bonds, list) {
> > + iommu = dev_to_iommu(bond->dev);
> > + if (iommu == prev)
> > + continue;
> > +
> > + prev = iommu;
> > + riscv_iommu_cmd_iofence(&cmd);
> > + riscv_iommu_cmd_send(iommu, &cmd, RISCV_IOMMU_QUEUE_TIMEOUT);
> > + }
> > + rcu_read_unlock();
> > +}
>
> Best regards,
> baolu
Best regards,
- Tomasz
