On 2021/2/1 19:14, Jean-Philippe Brucker wrote: > Hi Zhou, > > On Mon, Feb 01, 2021 at 09:18:42AM +0800, Zhou Wang wrote: >>> @@ -1033,8 +1076,7 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid, >>> FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid) | >>> CTXDESC_CD_0_V; >>> >>> - /* STALL_MODEL==0b10 && CD.S==0 is ILLEGAL */ >>> - if (smmu->features & ARM_SMMU_FEAT_STALL_FORCE) >>> + if (smmu_domain->stall_enabled) >> >> Could we add ssid checking here? like: if (smmu_domain->stall_enabled && ssid). >> The reason is if not CD.S will also be set when ssid is 0, which is not needed. > > Some drivers may want to get stall events on SSID 0: > https://lore.kernel.org/kvm/20210125090402.1429-1-lushenming@xxxxxxxxxx/#t Hi Jean, I did not notice this before. Yes, if we need to support IOPF in vfio, we need enable stall events on SSID 0. > > Are you seeing an issue with stall events on ssid 0? Normally there > shouldn't be any fault on this context, but if they happen and no handler It happened that there is bug in the test code of HiSilicon HPRE crypto driver. We used a wrong iova which triggered a SMMU event with stall bit :) > is registered, the SMMU driver will just abort them and report them like a > non-stall event. It will report event 0x10 with stall bit. Best, Zhou > > Thanks, > Jean > > . >
