Re: [RFC PATCH v3 17/18] hw/arm/smmuv3: Add property for OAS

[Mostafa Saleh <smostafa@google.com>]

Hi Eric,

On Tue, May 21, 2024 at 11:32:48AM +0200, Eric Auger wrote:
> Hi Mostafa,
> 
> On 4/29/24 05:24, Mostafa Saleh wrote:
> > Add property that sets the OAS of the SMMU, this in not used in this
> > patch.
> >
> > Signed-off-by: Mostafa Saleh <smostafa@google.com>
> > ---
> >  hw/arm/smmuv3-internal.h |  3 ++-
> >  hw/arm/smmuv3.c          | 29 ++++++++++++++++++++++++++++-
> >  include/hw/arm/smmuv3.h  |  1 +
> >  3 files changed, 31 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/arm/smmuv3-internal.h b/hw/arm/smmuv3-internal.h
> > index 0ebf2eebcf..dd91807624 100644
> > --- a/hw/arm/smmuv3-internal.h
> > +++ b/hw/arm/smmuv3-internal.h
> > @@ -111,7 +111,8 @@ REG32(IDR5,                0x14)
> >       FIELD(IDR5, VAX,        10, 2);
> >       FIELD(IDR5, STALL_MAX,  16, 16);
> >  
> > -#define SMMU_IDR5_OAS 4
> > +#define SMMU_IDR5_OAS_DEF 4 /* 44 bits. */
> > +#define SMMU_IDR5_OAS_MAX 5 /* 48 bits. */
> >  
> >  REG32(IIDR,                0x18)
> >  REG32(AIDR,                0x1c)
> > diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> > index 4ac818cf7a..39d03e7e24 100644
> > --- a/hw/arm/smmuv3.c
> > +++ b/hw/arm/smmuv3.c
> > @@ -299,7 +299,9 @@ static void smmuv3_init_regs(SMMUv3State *s)
> >      s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 1);
> >      s->idr[3] = FIELD_DP32(s->idr[3], IDR3, BBML, 2);
> >  
> > -    s->idr[5] = FIELD_DP32(s->idr[5], IDR5, OAS, SMMU_IDR5_OAS); /* 44 bits */
> > +    /* PTW doesn't support 52 bits. */
> remove the point
> > +    s->oas = MIN(s->oas, SMMU_IDR5_OAS_MAX);
> > +    s->idr[5] = FIELD_DP32(s->idr[5], IDR5, OAS, s->oas);
> >      /* 4K, 16K and 64K granule support */
> >      s->idr[5] = FIELD_DP32(s->idr[5], IDR5, GRAN4K, 1);
> >      s->idr[5] = FIELD_DP32(s->idr[5], IDR5, GRAN16K, 1);
> > @@ -1901,11 +1903,34 @@ static const VMStateDescription vmstate_gbpa = {
> >      }
> >  };
> >  
> > +static const VMStateDescription vmstate_oas = {
> > +    .name = "smmuv3/oas",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> don't you need a .needed function?
> 
> I tested backward migration and this fails
> qemu-system-aarch64: error while loading state for instance 0x0 of
> device 'smmuv3'
> qemu-system-aarch64: load of migration failed: No such file or directory
> post-processing ...

Yes, I think we need a .needed which returns if oas is not as default,
that should be backward compatiable (at least for this patch) and would
break when oas changes.

Thanks,
Mostafa
> 
> Thanks
> 
> Eric
> > +    .fields = (const VMStateField[]) {
> > +        VMSTATE_INT32(oas, SMMUv3State),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> > +static int smmuv3_preload(void *opaque)
> > +{
> > +    SMMUv3State *s = opaque;
> > +
> > +    /*
> > +     * In case it wasn't migrated, use the value used
> > +     * by older QEMU.
> > +     */
> > +    s->oas = SMMU_IDR5_OAS_DEF;
> > +    return 0;
> > +}
> > +
> >  static const VMStateDescription vmstate_smmuv3 = {
> >      .name = "smmuv3",
> >      .version_id = 1,
> >      .minimum_version_id = 1,
> >      .priority = MIG_PRI_IOMMU,
> > +    .pre_load = smmuv3_preload,
> >      .fields = (const VMStateField[]) {
> >          VMSTATE_UINT32(features, SMMUv3State),
> >          VMSTATE_UINT8(sid_size, SMMUv3State),
> > @@ -1933,6 +1958,7 @@ static const VMStateDescription vmstate_smmuv3 = {
> >      },
> >      .subsections = (const VMStateDescription * const []) {
> >          &vmstate_gbpa,
> > +        &vmstate_oas,
> >          NULL
> >      }
> >  };
> > @@ -1945,6 +1971,7 @@ static Property smmuv3_properties[] = {
> >       * Defaults to stage 1
> >       */
> >      DEFINE_PROP_STRING("stage", SMMUv3State, stage),
> > +    DEFINE_PROP_INT32("oas", SMMUv3State, oas, SMMU_IDR5_OAS_DEF),
> >      DEFINE_PROP_END_OF_LIST()
> >  };
> >  
> > diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> > index d183a62766..00a9eb4467 100644
> > --- a/include/hw/arm/smmuv3.h
> > +++ b/include/hw/arm/smmuv3.h
> > @@ -63,6 +63,7 @@ struct SMMUv3State {
> >      qemu_irq     irq[4];
> >      QemuMutex mutex;
> >      char *stage;
> > +    int32_t oas;
> >  };
> >  
> >  typedef enum {
>