Re: [PATCH v6 4/5] hw/arm/smmuv3: Introduce a helper function for event propagation

[Jonathan Cameron via <qemu-arm@nongnu.org>]

On Fri, 13 Feb 2026 10:39:41 +0000
Shameer Kolothum <skolothumtho@nvidia.com> wrote:

> Factor out the code that propagates event records to the guest into a
> helper function. The accelerated SMMUv3 path can use this to propagate
> host events in a subsequent patch.
> 
> Since this helper may be called from outside the SMMUv3 core, take the
> mutex before accessing the Event Queue.

Totally trivial but it might be worth stating that / why it is harmless
(or indeed necessary?) to take the lock in existing paths. I was kind
of expecting to see locked helper wrapping an unlocked version that was
used to replace the original code.  So guess I'm missing something.

> 
> No functional change intended.
> 
> Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
> ---
>  hw/arm/smmuv3-internal.h |  4 ++++
>  hw/arm/smmuv3.c          | 21 +++++++++++++++------
>  hw/arm/trace-events      |  2 +-
>  3 files changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/arm/smmuv3-internal.h b/hw/arm/smmuv3-internal.h
> index a6464425ec..b666109ad9 100644
> --- a/hw/arm/smmuv3-internal.h
> +++ b/hw/arm/smmuv3-internal.h
> @@ -352,7 +352,11 @@ typedef struct SMMUEventInfo {
>              (x)->word[6] = (uint32_t)(addr & 0xffffffff); \
>      } while (0)
>  
> +#define EVT_GET_TYPE(x)  extract32((x)->word[0], 0, 8)
> +#define EVT_GET_SID(x)   ((x)->word[1])
> +
>  void smmuv3_record_event(SMMUv3State *s, SMMUEventInfo *event);
> +void smmuv3_propagate_event(SMMUv3State *s, Evt *evt);
>  int smmu_find_ste(SMMUv3State *s, uint32_t sid, STE *ste, SMMUEventInfo *event);
>  
>  static inline int oas2bits(int oas_field)
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index f804d3af25..bcb9176c51 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -168,10 +168,23 @@ static MemTxResult smmuv3_write_eventq(SMMUv3State *s, Evt *evt)
>      return MEMTX_OK;
>  }
>  
> +void smmuv3_propagate_event(SMMUv3State *s, Evt *evt)
> +{
> +    MemTxResult r;
> +
> +    trace_smmuv3_propagate_event(smmu_event_string(EVT_GET_TYPE(evt)),
> +                                 EVT_GET_SID(evt));
> +    qemu_mutex_lock(&s->mutex);

Could use 
    QEMU_LOCK_GUARD(&s->mutex);

though gain is minor so feel free to not do so.

> +    r = smmuv3_write_eventq(s, evt);
> +    if (r != MEMTX_OK) {
> +        smmuv3_trigger_irq(s, SMMU_IRQ_GERROR, R_GERROR_EVENTQ_ABT_ERR_MASK);
> +    }
> +    qemu_mutex_unlock(&s->mutex);
> +}