Messages in this thread | | | Date | Tue, 22 Jun 2021 12:41:22 +0530 | From | Sai Prakash Ranjan <> | Subject | Re: [PATCHv2 1/3] iommu/io-pgtable: Add a quirk to use tlb_flush_all() for partial walk flush |
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Hi Robin,
On 2021-06-21 21:15, Robin Murphy wrote: > On 2021-06-18 03:51, Sai Prakash Ranjan wrote: >> Add a quirk IO_PGTABLE_QUIRK_TLB_INV_ALL to invalidate entire context >> with tlb_flush_all() callback in partial walk flush to improve unmap >> performance on select few platforms where the cost of >> over-invalidation >> is less than the unmap latency. > > I still think this doesn't belong anywhere near io-pgtable at all. > It's a driver-internal decision how exactly it implements a non-leaf > invalidation, and that may be more complex than a predetermined > boolean decision. For example, I've just realised for SMMUv3 we can't > invalidate multiple levels of table at once with a range command, > since if we assume the whole thing is mapped at worst-case page > granularity we may fail to invalidate any parts which are mapped as > intermediate-level blocks. If invalidating a 1GB region (with 4KB > granule) means having to fall back to 256K non-range commands, we may > not want to invalidate by VA then, even though doing so for a 2MB > region is still optimal. > > It's also quite feasible that drivers might want to do this for leaf > invalidations too - if you don't like issuing 512 commands to > invalidate 2MB, do you like issuing 511 commands to invalidate 2044KB? > - and at that point the logic really has to be in the driver anyway. >
Ok I will move this to tlb_flush_walk() functions in the drivers. In the previous v1 thread, you suggested to make the choice in iommu_get_dma_strict() test, I assume you meant the test in iommu_dma_init_domain() with a flag or was it the leaf driver(ex:arm-smmu.c) test of iommu_get_dma_strict() in init_domain?
I am still a bit confused on where this flag would be? Should this be a part of struct iommu_domain?
Thanks, Sai
> >> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> >> --- >> drivers/iommu/io-pgtable-arm.c | 3 ++- >> include/linux/io-pgtable.h | 5 +++++ >> 2 files changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/iommu/io-pgtable-arm.c >> b/drivers/iommu/io-pgtable-arm.c >> index 87def58e79b5..5d362f2214bd 100644 >> --- a/drivers/iommu/io-pgtable-arm.c >> +++ b/drivers/iommu/io-pgtable-arm.c >> @@ -768,7 +768,8 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg >> *cfg, void *cookie) >> if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS | >> IO_PGTABLE_QUIRK_NON_STRICT | >> IO_PGTABLE_QUIRK_ARM_TTBR1 | >> - IO_PGTABLE_QUIRK_ARM_OUTER_WBWA)) >> + IO_PGTABLE_QUIRK_ARM_OUTER_WBWA | >> + IO_PGTABLE_QUIRK_TLB_INV_ALL)) >> return NULL; >> data = arm_lpae_alloc_pgtable(cfg); >> diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h >> index 4d40dfa75b55..45441592a0e6 100644 >> --- a/include/linux/io-pgtable.h >> +++ b/include/linux/io-pgtable.h >> @@ -82,6 +82,10 @@ struct io_pgtable_cfg { >> * >> * IO_PGTABLE_QUIRK_ARM_OUTER_WBWA: Override the outer-cacheability >> * attributes set in the TCR for a non-coherent page-table walker. >> + * >> + * IO_PGTABLE_QUIRK_TLB_INV_ALL: Use TLBIALL/TLBIASID to invalidate >> + * entire context for partial walk flush to increase unmap >> + * performance on select few platforms. >> */ >> #define IO_PGTABLE_QUIRK_ARM_NS BIT(0) >> #define IO_PGTABLE_QUIRK_NO_PERMS BIT(1) >> @@ -89,6 +93,7 @@ struct io_pgtable_cfg { >> #define IO_PGTABLE_QUIRK_NON_STRICT BIT(4) >> #define IO_PGTABLE_QUIRK_ARM_TTBR1 BIT(5) >> #define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA BIT(6) >> + #define IO_PGTABLE_QUIRK_TLB_INV_ALL BIT(7) >> unsigned long quirks; >> unsigned long pgsize_bitmap; >> unsigned int ias; >>
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