On Mon, Jul 01, 2024 at 11:02:31AM +0000, Mostafa Saleh wrote:
> In the next patch, combine_tlb() will be added which combines 2 TLB
> entries into one for nested translations, which chooses the granule
> and level from the smallest entry.
>
> This means that with nested translation, an entry can be cached with
> the granule of stage-2 and not stage-1.
>
> However, currently, the lookup for an IOVA is done with input stage
> granule, which is stage-1 for nested configuration, which will not
> work with the above logic.
> This patch reworks lookup in that case, so it falls back to stage-2
> granule if no entry is found using stage-1 granule.
Why not initialize tt_combined to the minimum granule of stages 1 and 2?
It looks like you introduced it for this. I'm wondering if we lookup the
wrong IOVA if changing the granule size after the address is masked in
smmu_translate()
Thanks,
Jean
>
> Signed-off-by: Mostafa Saleh <smost...@google.com>
> ---
> hw/arm/smmu-common.c | 36 ++++++++++++++++++++++++++++++++++--
> 1 file changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/hw/arm/smmu-common.c b/hw/arm/smmu-common.c
> index 21982621c0..0840b5cffd 100644
> --- a/hw/arm/smmu-common.c
> +++ b/hw/arm/smmu-common.c
> @@ -66,8 +66,10 @@ SMMUIOTLBKey smmu_get_iotlb_key(int asid, int vmid,
> uint64_t iova,
> return key;
> }
>
> -SMMUTLBEntry *smmu_iotlb_lookup(SMMUState *bs, SMMUTransCfg *cfg,
> - SMMUTransTableInfo *tt, hwaddr iova)
> +static SMMUTLBEntry *smmu_iotlb_lookup_all_levels(SMMUState *bs,
> + SMMUTransCfg *cfg,
> + SMMUTransTableInfo *tt,
> + hwaddr iova)
> {
> uint8_t tg = (tt->granule_sz - 10) / 2;
> uint8_t inputsize = 64 - tt->tsz;
> @@ -88,6 +90,36 @@ SMMUTLBEntry *smmu_iotlb_lookup(SMMUState *bs,
> SMMUTransCfg *cfg,
> }
> level++;
> }
> + return entry;
> +}
> +
> +/**
> + * smmu_iotlb_lookup - Look up for a TLB entry.
> + * @bs: SMMU state which includes the TLB instance
> + * @cfg: Configuration of the translation
> + * @tt: Translation table info (granule and tsz)
> + * @iova: IOVA address to lookup
> + *
> + * returns a valid entry on success, otherwise NULL.
> + * In case of nested translation, tt can be updated to include
> + * the granule of the found entry as it might different from
> + * the IOVA granule.
> + */
> +SMMUTLBEntry *smmu_iotlb_lookup(SMMUState *bs, SMMUTransCfg *cfg,
> + SMMUTransTableInfo *tt, hwaddr iova)
> +{
> + SMMUTLBEntry *entry = NULL;
> +
> + entry = smmu_iotlb_lookup_all_levels(bs, cfg, tt, iova);
> + /*
> + * For nested translation also try the s2 granule, as the TLB will insert
> + * it if the size of s2 tlb entry was smaller.
> + */
> + if (!entry && (cfg->stage == SMMU_NESTED) &&
> + (cfg->s2cfg.granule_sz != tt->granule_sz)) {
> + tt->granule_sz = cfg->s2cfg.granule_sz;
> + entry = smmu_iotlb_lookup_all_levels(bs, cfg, tt, iova);
> + }
>
> if (entry) {
> cfg->iotlb_hits++;
> --
> 2.45.2.803.g4e1b14247a-goog
>
