Re: [PATCH v4 3/5] iommu/io-pgtable-arm: add support for non-strict mode

["Leizhen (ThunderTown)" <thunder.leizhen-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

On 2018/8/9 18:54, Robin Murphy wrote:
> On 06/08/18 13:27, Zhen Lei wrote:
>> To support the non-strict mode, now we only tlbi and sync for the strict
>> mode. But for the non-leaf case, always follow strict mode.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>> ---
>>   drivers/iommu/io-pgtable-arm.c | 27 ++++++++++++++++++---------
>>   drivers/iommu/io-pgtable.h     |  3 +++
>>   2 files changed, 21 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
>> index 010a254..bb61bef 100644
>> --- a/drivers/iommu/io-pgtable-arm.c
>> +++ b/drivers/iommu/io-pgtable-arm.c
>> @@ -292,7 +292,7 @@ static void __arm_lpae_set_pte(arm_lpae_iopte *ptep, arm_lpae_iopte pte,
>>
>>   static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
>>                      unsigned long iova, size_t size, int lvl,
>> -                   arm_lpae_iopte *ptep);
>> +                   arm_lpae_iopte *ptep, bool strict);
>>
>>   static void __arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
>>                   phys_addr_t paddr, arm_lpae_iopte prot,
>> @@ -319,6 +319,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
>>                    arm_lpae_iopte prot, int lvl,
>>                    arm_lpae_iopte *ptep)
>>   {
>> +    size_t unmapped;
>>       arm_lpae_iopte pte = *ptep;
>>
>>       if (iopte_leaf(pte, lvl)) {
>> @@ -334,7 +335,8 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
>>           size_t sz = ARM_LPAE_BLOCK_SIZE(lvl, data);
>>
>>           tblp = ptep - ARM_LPAE_LVL_IDX(iova, lvl, data);
>> -        if (WARN_ON(__arm_lpae_unmap(data, iova, sz, lvl, tblp) != sz))
>> +        unmapped = __arm_lpae_unmap(data, iova, sz, lvl, tblp, true);
>> +        if (WARN_ON(unmapped != sz))
> 
> What's the extra local variable for?

in order to remove the warning: more than 80 characters a line

> 
>>               return -EINVAL;
>>       }
>>
>> @@ -576,15 +578,17 @@ static size_t arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data,
>>       }
>>
>>       if (unmap_idx < 0)
>> -        return __arm_lpae_unmap(data, iova, size, lvl, tablep);
>> +        return __arm_lpae_unmap(data, iova, size, lvl, tablep, true);
>>
>>       io_pgtable_tlb_add_flush(&data->iop, iova, size, size, true);
>> +    io_pgtable_tlb_sync(&data->iop);
>> +
>>       return size;
>>   }
>>
>>   static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
>>                      unsigned long iova, size_t size, int lvl,
>> -                   arm_lpae_iopte *ptep)
>> +                   arm_lpae_iopte *ptep, bool strict)
>>   {
>>       arm_lpae_iopte pte;
>>       struct io_pgtable *iop = &data->iop;
>> @@ -609,7 +613,7 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
>>               io_pgtable_tlb_sync(iop);
>>               ptep = iopte_deref(pte, data);
>>               __arm_lpae_free_pgtable(data, lvl + 1, ptep);
>> -        } else {
>> +        } else if (strict) {
> 
> Since this is the only place we ever actually evaluate "strict", can't we just test iop->cfg.quirks directly at this point instead of playing pass-the-parcel with the extra argument?

Wonderful, you're right!

> 
> Robin.
> 
>>               io_pgtable_tlb_add_flush(iop, iova, size, size, true);
>>           }
>>
>> @@ -625,12 +629,13 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
>>
>>       /* Keep on walkin' */
>>       ptep = iopte_deref(pte, data);
>> -    return __arm_lpae_unmap(data, iova, size, lvl + 1, ptep);
>> +    return __arm_lpae_unmap(data, iova, size, lvl + 1, ptep, strict);
>>   }
>>
>>   static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
>>                    size_t size)
>>   {
>> +    bool strict;
>>       struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
>>       arm_lpae_iopte *ptep = data->pgd;
>>       int lvl = ARM_LPAE_START_LVL(data);
>> @@ -638,7 +643,9 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
>>       if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias)))
>>           return 0;
>>
>> -    return __arm_lpae_unmap(data, iova, size, lvl, ptep);
>> +    strict = !(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NON_STRICT);
>> +
>> +    return __arm_lpae_unmap(data, iova, size, lvl, ptep, strict);
>>   }
>>
>>   static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
>> @@ -771,7 +778,8 @@ static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg)
>>       u64 reg;
>>       struct arm_lpae_io_pgtable *data;
>>
>> -    if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS | IO_PGTABLE_QUIRK_NO_DMA))
>> +    if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS | IO_PGTABLE_QUIRK_NO_DMA |
>> +            IO_PGTABLE_QUIRK_NON_STRICT))
>>           return NULL;
>>
>>       data = arm_lpae_alloc_pgtable(cfg);
>> @@ -863,7 +871,8 @@ static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg)
>>       struct arm_lpae_io_pgtable *data;
>>
>>       /* The NS quirk doesn't apply at stage 2 */
>> -    if (cfg->quirks & ~IO_PGTABLE_QUIRK_NO_DMA)
>> +    if (cfg->quirks & ~(IO_PGTABLE_QUIRK_NO_DMA |
>> +        IO_PGTABLE_QUIRK_NON_STRICT))
>>           return NULL;
>>
>>       data = arm_lpae_alloc_pgtable(cfg);
>> diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
>> index 2df7909..beb14a3 100644
>> --- a/drivers/iommu/io-pgtable.h
>> +++ b/drivers/iommu/io-pgtable.h
>> @@ -71,12 +71,15 @@ struct io_pgtable_cfg {
>>        *    be accessed by a fully cache-coherent IOMMU or CPU (e.g. for a
>>        *    software-emulated IOMMU), such that pagetable updates need not
>>        *    be treated as explicit DMA data.
>> +     * IO_PGTABLE_QUIRK_NON_STRICT: Put off TLBs invalidation and release
>> +     *    memory first.
>>        */
>>       #define IO_PGTABLE_QUIRK_ARM_NS        BIT(0)
>>       #define IO_PGTABLE_QUIRK_NO_PERMS    BIT(1)
>>       #define IO_PGTABLE_QUIRK_TLBI_ON_MAP    BIT(2)
>>       #define IO_PGTABLE_QUIRK_ARM_MTK_4GB    BIT(3)
>>       #define IO_PGTABLE_QUIRK_NO_DMA        BIT(4)
>> +    #define IO_PGTABLE_QUIRK_NON_STRICT    BIT(5)
>>       unsigned long            quirks;
>>       unsigned long            pgsize_bitmap;
>>       unsigned int            ias;
>> -- 
>> 1.8.3
>>
>>
> 
> .
> 

-- 
Thanks!
BestRegards