Re: [PATCH 3/5] hw/arm/smmuv3: Align stream table base address to table size

[Auger Eric <eric.auger@redhat.com>]

Hi Simon,

On 12/4/19 2:55 PM, Simon Veith wrote:
> Per the specification, and as observed in hardware, the SMMUv3 aligns
> the SMMU_STRTAB_BASE address to the size of the table by masking out the
> respective least significant bits in the ADDR field.
> 
> Apply this masking logic to our smmu_find_ste() lookup function per the
> specification.
> 
> ref. ARM IHI 0070C, section 6.3.23.
> 
> Signed-off-by: Simon Veith <sveith@amazon.de>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: qemu-devel@nongnu.org
> Cc: qemu-arm@nongnu.org
> ---
>  hw/arm/smmuv3.c | 29 +++++++++++++++++++++++++----
>  1 file changed, 25 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index aad4639..2d6c275 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -376,8 +376,9 @@ bad_ste:
>  static int smmu_find_ste(SMMUv3State *s, uint32_t sid, STE *ste,
>                           SMMUEventInfo *event)
>  {
> -    dma_addr_t addr;
> +    dma_addr_t addr, strtab_base;
>      uint32_t log2size;
> +    int strtab_size_shift;
>      int ret;
>  
>      trace_smmuv3_find_ste(sid, s->features, s->sid_split);
> @@ -391,10 +392,23 @@ static int smmu_find_ste(SMMUv3State *s, uint32_t sid, STE *ste,
>      }
>      if (s->features & SMMU_FEATURE_2LVL_STE) {
>          int l1_ste_offset, l2_ste_offset, max_l2_ste, span;
> -        dma_addr_t strtab_base, l1ptr, l2ptr;
> +        dma_addr_t l1ptr, l2ptr;
>          STEDesc l1std;
>  
> -        strtab_base = s->strtab_base & SMMU_BASE_ADDR_MASK;
> +        /*
> +         * Align strtab base address to table size. For this purpose, assume it
> +         * is not bounded by SMMU_IDR1_SIDSIZE.
> +         */
> +        strtab_size_shift = log2size - s->sid_split - 1 + 3;
Maybe just as the spec use MAX(5, (LOG2SIZE-SPLIT-1+3))?
> +        if (strtab_size_shift < DMA_ADDR_BITS) {
> +            if (strtab_size_shift < 5) {
> +                strtab_size_shift = 5;
> +            }
> +            strtab_base = s->strtab_base & SMMU_BASE_ADDR_MASK &
> +                          ~((1ULL << strtab_size_shift) - 1);
nit: you may use ~MAKE_64BIT_MASK(0, strtab_size_shift)
> +        } else {
see below
> +            strtab_base = 0;
> +        }
>          l1_ste_offset = sid >> s->sid_split;
>          l2_ste_offset = sid & ((1 << s->sid_split) - 1);
>          l1ptr = (dma_addr_t)(strtab_base + l1_ste_offset * sizeof(l1std));
> @@ -433,7 +447,14 @@ static int smmu_find_ste(SMMUv3State *s, uint32_t sid, STE *ste,
>          }
>          addr = l2ptr + l2_ste_offset * sizeof(*ste);
>      } else {
> -        addr = (s->strtab_base & SMMU_BASE_ADDR_MASK) + sid * sizeof(*ste);
> +        strtab_size_shift = log2size + 5;
> +        if (strtab_size_shift < DMA_ADDR_BITS) {
> +            strtab_base = s->strtab_base & SMMU_BASE_ADDR_MASK &
> +                          ~((1ULL << strtab_size_shift) - 1);
> +        } else {
Can it happen? I understand LOG2SIZE <= SMMU_S_IDR_5.SIDSIZE
and SIDSIZE is max 32. Same above?
> +            strtab_base = 0;
> +        }
> +        addr = strtab_base + sid * sizeof(*ste);
>      }
>  
>      if (smmu_get_ste(s, addr, ste, event)) {
> 
Thank you for those series fixes.

Best Regards

Eric