Messages in this thread | | | Subject | Re: [PATCH v2 1/1] iommu/arm-smmu-v3: Fix error case of range command | From | zhurui <> | Date | Sun, 6 Aug 2023 13:28:04 +0800 |
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On 2023/8/5 2:30, Nicolin Chen wrote: > On Fri, Aug 04, 2023 at 05:52:25PM +0100, Will Deacon wrote: >> On Fri, Aug 04, 2023 at 05:31:20PM +0800, zhurui wrote: >>> When tg != 0 but ttl, scale, num all 0 in a range tlbi command, it >>> is reserved and will cause the CERROR_ILL error. This case means >>> that the size to be invalidated is only one page size, and the >>> range invalidation is meaningless here. So we set tg to 0 in this >>> case to do an non-range invalidation instead. > >>> @@ -1930,6 +1927,12 @@ static void __arm_smmu_tlb_inv_range(struct arm_smmu_cmdq_ent *cmd, >>> num = (num_pages >> scale) & CMDQ_TLBI_RANGE_NUM_MAX; >>> cmd->tlbi.num = num - 1; >>> >>> + /* Prevent error caused by one page tlbi with leaf 0 */ >>> + if (scale == 0 && num == 1 && cmd->tlbi.leaf == 0) >>> + cmd->tlbi.tg = 0; >> >> This should only be true for the last iteration, right (i.e. when num_pages >> == 1)? In which case, I'd prefer to leave the old code as-is and just add: >> >> /* Single-page leaf invalidation requires a TG field of 0 */ >> if (num_pages == 1 && !cmd->tlbi.leaf) >> cmd->tlbi.tg = 0;To Will and Nicolin,
Not only the last iteration, it's the result of __ffs function. For example, if numpages is 33, then the value of __ffs(num_pages) is 0, so the value of scale is also 0. The value of num depends on CMDQ_TLBI_RANGE_NUM_MAX. That is, the maximum value of num is 31. Therefore, the final value of num is 1. So, if consider CMDQ_TLBI_RANGE_NUM_MAX, there will be some case not the last one page but the beginning pages. That's why I use scale and num as conditions, not num_pages. Then I should reassign tg based on the result.
> > Is "!cmd->tlbi.leaf" to be "leaf" or "non-leaf"? > > IIUIC, this "num_pages == 1" implies "NUM == 0, SCALE == 0" while > the "!cmd->tlbi.leaf" implies "TTL = 0b00", which in combination > would result in a CERROR_ILL mentioned by the spec? > > I feel this could be more clear by just checking the three fields > following the spec...> > Thanks > Nicolin > . > Yes, based on spec 4.4.1.1 for ARM IHI 0070, after the TLL and TG table, there is a description for TG != 0b00, and you can check it in the last point.
Thanks. ZhuRui .
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