Re: [PATCH v3 3/6] hw/arm/smmuv3: Check stream IDs against actual table LOG2SIZE

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

Hi Simon,

On 12/16/19 4:15 PM, Simon Veith wrote:
> When checking whether a stream ID is in range of the stream table, we
> have so far been only checking it against our implementation limit
> (SMMU_IDR1_SIDSIZE). However, the guest can program the
> STRTAB_BASE_CFG.LOG2SIZE field to a size that is smaller than this
> limit.
> 
> Check the stream ID against this limit as well to match the hardware
> behavior of raising C_BAD_STREAMID events in case the limit is exceeded.
> Also, ensure that we do not go one entry beyond the end of the table by
> checking that its index is strictly smaller than the table size.
> 
> ref. ARM IHI 0070C, section 6.3.24.
> 
> 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
Acked-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric
> ---
> Changed in v2:
> 
> * Also check that stream ID is strictly lower than the table size
> 
>  hw/arm/smmuv3.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index eef9a18..727558b 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -377,11 +377,15 @@ static int smmu_find_ste(SMMUv3State *s, uint32_t sid, STE *ste,
>                           SMMUEventInfo *event)
>  {
>      dma_addr_t addr;
> +    uint32_t log2size;
>      int ret;
>  
>      trace_smmuv3_find_ste(sid, s->features, s->sid_split);
> -    /* Check SID range */
> -    if (sid > (1 << SMMU_IDR1_SIDSIZE)) {
> +    log2size = FIELD_EX32(s->strtab_base_cfg, STRTAB_BASE_CFG, LOG2SIZE);
> +    /*
> +     * Check SID range against both guest-configured and implementation limits
> +     */
> +    if (sid >= (1 << MIN(log2size, SMMU_IDR1_SIDSIZE))) {
>          event->type = SMMU_EVT_C_BAD_STREAMID;
>          return -EINVAL;
>      }
>