On Tue, Jan 28, 2020 at 2:34 PM Jordan Crouse <jcrouse@xxxxxxxxxxxxxx> wrote: > > Domains which are being set up for split pagetables usually want to be > on a specific context bank for hardware reasons. Force the context > bank for domains with the split-pagetable quirk to context bank 0. > If context bank 0 is taken, move that context bank to another unused > bank and rewrite the stream matching registers accordingly. Is the only reason for dealing with the case that bank 0 is already in use, due to the DMA domain that gets setup before driver probes? I'm kinda thinking that we need to invent a way to unwind/detatch the DMA domain, and unhook the iommu-dmaops, since this seems to already be already causing problems with dma-bufs imported from other drivers (who expect that dma_map_*(), with the importing device's dev ptr, will do something sane. BR, -R > > This is be used by [1] and [2] to leave context bank 0 open so that > the Adreno GPU can program it. > > [1] https://lists.linuxfoundation.org/pipermail/iommu/2020-January/041438.html > [2] https://lists.linuxfoundation.org/pipermail/iommu/2020-January/041444.html > > Signed-off-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx> > --- > > drivers/iommu/arm-smmu.c | 63 +++++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 59 insertions(+), 4 deletions(-) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index 85a6773..799a254 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -254,6 +254,43 @@ static int __arm_smmu_alloc_bitmap(unsigned long *map, int start, int end) > return idx; > } > > +static void arm_smmu_write_s2cr(struct arm_smmu_device *smmu, int idx); > + > +static int __arm_smmu_alloc_cb(struct arm_smmu_device *smmu, int start, > + int target) > +{ > + int new, i; > + > + /* Allocate a new context bank id */ > + new = __arm_smmu_alloc_bitmap(smmu->context_map, start, > + smmu->num_context_banks); > + > + if (new < 0) > + return new; > + > + /* If no target is set or we actually got the bank index we wanted */ > + if (target == -1 || new == target) > + return new; > + > + /* Copy the context configuration to the new index */ > + memcpy(&smmu->cbs[new], &smmu->cbs[target], sizeof(*smmu->cbs)); > + smmu->cbs[new].cfg->cbndx = new; > + > + /* FIXME: Do we need locking here? */ > + for (i = 0; i < smmu->num_mapping_groups; i++) { > + if (smmu->s2crs[i].cbndx == target) { > + smmu->s2crs[i].cbndx = new; > + arm_smmu_write_s2cr(smmu, i); > + } > + } > + > + /* > + * FIXME: Does getting here imply that 'target' is already set in the > + * context_map? > + */ > + return target; > +} > + > static void __arm_smmu_free_bitmap(unsigned long *map, int idx) > { > clear_bit(idx, map); > @@ -770,6 +807,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, > struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); > struct arm_smmu_cfg *cfg = &smmu_domain->cfg; > unsigned long quirks = 0; > + int forcecb = -1; > > mutex_lock(&smmu_domain->init_mutex); > if (smmu_domain->smmu) > @@ -844,8 +882,25 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, > * SEP_UPSTREAM so we don't need to reduce the size of > * the ias to account for the sign extension bit > */ > - if (smmu_domain->split_pagetables) > - quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1; > + if (smmu_domain->split_pagetables) { > + /* > + * If split pagetables are enabled, assume that > + * the user's intent is to use per-instance > + * pagetables which, at least on a QCOM target, > + * means that this domain should be on context > + * bank 0. > + */ > + > + /* > + * If we can't force to context bank 0 then > + * don't bother enabling split pagetables which > + * then would not allow aux domains > + */ > + if (start == 0) { > + forcecb = 0; > + quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1; > + } > + } > } else if (cfg->fmt == ARM_SMMU_CTX_FMT_AARCH32_L) { > fmt = ARM_32_LPAE_S1; > ias = min(ias, 32UL); > @@ -883,8 +938,8 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, > ret = -EINVAL; > goto out_unlock; > } > - ret = __arm_smmu_alloc_bitmap(smmu->context_map, start, > - smmu->num_context_banks); > + > + ret = __arm_smmu_alloc_cb(smmu, start, forcecb); > if (ret < 0) > goto out_unlock; > > -- > 2.7.4
