Messages in this thread | | | Date | Fri, 18 Aug 2023 17:19:31 +0100 | Subject | Re: [PATCH v2 1/1] iommu/arm-smmu-v3: Fix error case of range command | From | Robin Murphy <> |
| |
On 2023-08-09 14:48, Robin Murphy wrote: [...] > Does the patch below work for you?
Any comments on this? Just noticed this commit on a local dev branch and realised I'd totally forgotten about it already. I'm pretty confident it ought to be right, but then it *was* also me who missed the original bug to begin with... ;) Thanks, Robin.
> ----->8----- > Subject: [PATCH] iommu/arm-smmu-v3: Avoid constructing invalid range > commands > > Although io-pgtable's non-leaf invalidations are always for full tables, > I missed that SVA also uses non-leaf invalidations, while being at the > mercy of whatever range the MMU notifier throws at it. This means it > definitely wants the previous TTL fix as well, since it also doesn't > know exactly which leaf level(s) may need invalidating, but it can also > give us less-aligned ranges wherein certain corners may lead to building > an invalid command where TTL, Num and Scale are all 0. It should be fine > to handle this by over-invalidating an extra page, since falling back to > a non-range command opens up a whole can of errata-flavoured worms. > > Fixes: 6833b8f2e199 ("iommu/arm-smmu-v3: Set TTL invalidation hint better") > Reported-by: Rui Zhu <zhurui3@huawei.com> > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > index 9b0dc3505601..6ccbae9b93a1 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -1895,18 +1895,23 @@ static void __arm_smmu_tlb_inv_range(struct > arm_smmu_cmdq_ent *cmd, > /* Get the leaf page size */ > tg = __ffs(smmu_domain->domain.pgsize_bitmap); > > + num_pages = size >> tg; > + > /* Convert page size of 12,14,16 (log2) to 1,2,3 */ > cmd->tlbi.tg = (tg - 10) / 2; > > /* > - * Determine what level the granule is at. For non-leaf, > io-pgtable > - * assumes .tlb_flush_walk can invalidate multiple levels at once, > - * so ignore the nominal last-level granule and leave TTL=0. > + * Determine what level the granule is at. For non-leaf, both > + * io-pgtable and SVA pass a nominal last-level granule because > + * they don't know what level(s) actually apply, so ignore that > + * and leave TTL=0. However for various errata reasons we still > + * want to use a range command, so avoid the SVA corner case > + * where both scale and num could be 0 as well. > */ > if (cmd->tlbi.leaf) > cmd->tlbi.ttl = 4 - ((ilog2(granule) - 3) / (tg - 3)); > - > - num_pages = size >> tg; > + else if ((num_pages & CMDQ_TLBI_RANGE_NUM_MAX) == 1) > + num_pages++; > } > > cmds.num = 0; >
| |