Re: [PATCH v4 03/19] hw/arm/smmuv3: Fix encoding of CLASS in events

[Mostafa Saleh <smostafa@google.com>]

Hi Jean,

On Thu, Jul 04, 2024 at 07:02:00PM +0100, Jean-Philippe Brucker wrote:
> On Mon, Jul 01, 2024 at 11:02:25AM +0000, Mostafa Saleh wrote:
> > The SMMUv3 spec (ARM IHI 0070 F.b - 7.3 Event records) defines the
> > class of events faults as:
> > 
> > CLASS: The class of the operation that caused the fault:
> > - 0b00: CD, CD fetch.
> > - 0b01: TTD, Stage 1 translation table fetch.
> > - 0b10: IN, Input address
> > 
> > However, this value was not set and left as 0 which means CD and not
> > IN (0b10).
> > While at it, add an enum for class as it would be used for nesting.
> > However, at the moment stage-1 and stage-2 use the same class values.
> > 
> > Fixes: 9bde7f0674 “hw/arm/smmuv3: Implement translate callback”
> > Reviewed-by: Eric Auger <eric.auger@redhat.com>
> > Signed-off-by: Mostafa Saleh <smostafa@google.com>
> > ---
> >  hw/arm/smmuv3-internal.h | 6 ++++++
> >  hw/arm/smmuv3.c          | 6 +++++-
> >  2 files changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/arm/smmuv3-internal.h b/hw/arm/smmuv3-internal.h
> > index e4dd11e1e6..0f3ecec804 100644
> > --- a/hw/arm/smmuv3-internal.h
> > +++ b/hw/arm/smmuv3-internal.h
> > @@ -32,6 +32,12 @@ typedef enum SMMUTranslationStatus {
> >      SMMU_TRANS_SUCCESS,
> >  } SMMUTranslationStatus;
> >  
> > +typedef enum SMMUTranslationClass {
> > +    SMMU_CLASS_CD,
> > +    SMMU_CLASS_TT,
> > +    SMMU_CLASS_IN,
> > +} SMMUTranslationClass;
> > +
> >  /* MMIO Registers */
> >  
> >  REG32(IDR0,                0x0)
> > diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> > index 9dd3ea48e4..1eb5b160d2 100644
> > --- a/hw/arm/smmuv3.c
> > +++ b/hw/arm/smmuv3.c
> > @@ -942,7 +942,7 @@ static IOMMUTLBEntry smmuv3_translate(IOMMUMemoryRegion *mr, hwaddr addr,
> >              event.type = SMMU_EVT_F_WALK_EABT;
> >              event.u.f_walk_eabt.addr = addr;
> >              event.u.f_walk_eabt.rnw = flag & 0x1;
> > -            event.u.f_walk_eabt.class = 0x1;
> > +            event.u.f_walk_eabt.class = SMMU_CLASS_TT;
> 
> For EABT I think we have to differentiate S1/S2:
> 
> * s1-only walk that encounters EABT on S1 descriptor access is reported as
>   class=TT, 
> * s2 walk that encounters EABT on S2 descriptor while translating
>   non-descriptor IPA is reported as class=IN, even when doing s2-only.
> 
> Maybe it can be done in the later patch where you propagate the different
> classes, because it's a minor detail.

Thanks, for pointing it out. It is a bit tricky, for s2 only we need
class = IN which is easy.
But for nested, if we get a fault with s2 == 1 and EABT, we need to know
if it’s from:
- Translation of a s1 table IPA (translate_table_addr_ipa) as class => TT
- Access for s2 table as class = IN

We might need a new member in SMMUPTWEventInfo to distinguish this as
bool is_ipa_descriptor

Thanks,
Mostafa

> 
> Thanks,
> Jean
> 
> >              event.u.f_walk_eabt.addr2 = ptw_info.addr;
> >              break;
> >          case SMMU_PTW_ERR_TRANSLATION:
> > @@ -950,6 +950,7 @@ static IOMMUTLBEntry smmuv3_translate(IOMMUMemoryRegion *mr, hwaddr addr,
> >                  event.type = SMMU_EVT_F_TRANSLATION;
> >                  event.u.f_translation.addr = addr;
> >                  event.u.f_translation.addr2 = ptw_info.addr;
> > +                event.u.f_translation.class = SMMU_CLASS_IN;
> >                  event.u.f_translation.rnw = flag & 0x1;
> >              }
> >              break;
> > @@ -958,6 +959,7 @@ static IOMMUTLBEntry smmuv3_translate(IOMMUMemoryRegion *mr, hwaddr addr,
> >                  event.type = SMMU_EVT_F_ADDR_SIZE;
> >                  event.u.f_addr_size.addr = addr;
> >                  event.u.f_addr_size.addr2 = ptw_info.addr;
> > +                event.u.f_translation.class = SMMU_CLASS_IN;
> >                  event.u.f_addr_size.rnw = flag & 0x1;
> >              }
> >              break;
> > @@ -966,6 +968,7 @@ static IOMMUTLBEntry smmuv3_translate(IOMMUMemoryRegion *mr, hwaddr addr,
> >                  event.type = SMMU_EVT_F_ACCESS;
> >                  event.u.f_access.addr = addr;
> >                  event.u.f_access.addr2 = ptw_info.addr;
> > +                event.u.f_translation.class = SMMU_CLASS_IN;
> >                  event.u.f_access.rnw = flag & 0x1;
> >              }
> >              break;
> > @@ -974,6 +977,7 @@ static IOMMUTLBEntry smmuv3_translate(IOMMUMemoryRegion *mr, hwaddr addr,
> >                  event.type = SMMU_EVT_F_PERMISSION;
> >                  event.u.f_permission.addr = addr;
> >                  event.u.f_permission.addr2 = ptw_info.addr;
> > +                event.u.f_translation.class = SMMU_CLASS_IN;
> >                  event.u.f_permission.rnw = flag & 0x1;
> >              }
> >              break;
> > -- 
> > 2.45.2.803.g4e1b14247a-goog
> >