Hi Eric,
On Mon, May 20, 2024 at 10:27:50AM +0200, Eric Auger wrote:
> Hi Mostafa,
>
> On 4/29/24 05:23, Mostafa Saleh wrote:
> > In the previous patch, comine_tlb() was added which combines 2 TLB
> > entries into one, which chooses the granule and level from the
> > smallest entry.
> >
> > This means that a nested translation, an entry can be cached with the
> > granule of stage-2 and not stage-1.
> >
> > However, the lookup for an IOVA in nested configuration is done with
> > stage-1 granule, this patch reworks lookup in that case, so it falls
> > back to stage-2 granule if no entry is found using stage-1 granule.
> >
> > Signed-off-by: Mostafa Saleh <smost...@google.com>
> > ---
> > hw/arm/smmu-common.c | 24 ++++++++++++++++++++++--
> > 1 file changed, 22 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/arm/smmu-common.c b/hw/arm/smmu-common.c
> > index 0d6945fa54..c67af3bc6d 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 +90,24 @@ SMMUTLBEntry *smmu_iotlb_lookup(SMMUState *bs,
> > SMMUTransCfg *cfg,
> > }
> > level++;
> > }
> > + return entry;
> > +}
> > +
> > +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;
> is it safe to alter the tt->granule_sz without restoring it? In the
> positive I think this would deserve a comment.
It should be safe in the current usage, I will add a comment to
clarify how the function behaves (something as the the granule_sz
would be updated to the entry tg if found)
Thanks,
Mostafa
>
> Eric
> > + entry = smmu_iotlb_lookup_all_levels(bs, cfg, tt, iova);
> > + }
> >
> > if (entry) {
> > cfg->iotlb_hits++;
>
