Hi Shameer, On 12/4/25 10:22 AM, Shameer Kolothum wrote: > Install an event handler on the vEVENTQ fd to read and propagate host > generated vIOMMU events to the guest. > > The handler runs in QEMU’s main loop, using a non-blocking fd registered > via qemu_set_fd_handler(). is it future proof to do that in the main loop? > > Signed-off-by: Shameer Kolothum <[email protected]> > --- > hw/arm/smmuv3-accel.c | 58 +++++++++++++++++++++++++++++++++++++++++++ > hw/arm/smmuv3-accel.h | 2 ++ > 2 files changed, 60 insertions(+) > > diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c > index 74f0be3731..d320c62b04 100644 > --- a/hw/arm/smmuv3-accel.c > +++ b/hw/arm/smmuv3-accel.c > @@ -378,6 +378,58 @@ bool smmuv3_accel_issue_inv_cmd(SMMUv3State *bs, void > *cmd, SMMUDevice *sdev, > sizeof(Cmd), &entry_num, cmd, errp); > } > > +static void smmuv3_accel_event_read(void *opaque) So if I understand correctly this handler is called for every header/data. There cannot be several of them to be consumed in the queue? > +{ > + SMMUv3State *s = opaque; > + SMMUv3AccelState *accel = s->s_accel; > + struct { > + struct iommufd_vevent_header hdr; > + struct iommu_vevent_arm_smmuv3 vevent; > + } buf; > + ssize_t readsz = sizeof(buf); > + uint32_t last_seq = accel->last_event_seq; > + ssize_t bytes; > + > + bytes = read(accel->veventq->veventq_fd, &buf, readsz); > + if (bytes <= 0) { > + if (errno == EAGAIN || errno == EINTR) { > + return; > + } > + error_report("vEVENTQ: read failed (%s)", strerror(errno)); nit you can use %m directly > + return; > + } > + > + if (bytes < readsz) { > + error_report("vEVENTQ: incomplete read (%zd/%zd bytes)", bytes, > readsz); > + return; > + } > + > + if (buf.hdr.flags & IOMMU_VEVENTQ_FLAG_LOST_EVENTS) { > + error_report("vEVENTQ has lost events"); once you get a lost_event, don't you need to reset the last_event_seq, event_start to be able to consume again? > + return; > + } > + > + /* Check sequence in hdr for lost events if any */ > + if (accel->event_start) { > + uint32_t expected = (last_seq == INT_MAX) ? 0 : last_seq + 1; > + > + if (buf.hdr.sequence != expected) { > + uint32_t delta; > + > + if (buf.hdr.sequence >= last_seq) { > + delta = buf.hdr.sequence - last_seq; > + } else { > + /* Handle wraparound from INT_MAX */ > + delta = (INT_MAX - last_seq) + buf.hdr.sequence + 1; > + } > + error_report("vEVENTQ: detected lost %u event(s)", delta - 1); do we want to report all losses or just warn once? > + } > + } > + accel->last_event_seq = buf.hdr.sequence; > + accel->event_start = true; > + smmuv3_propagate_event(s, (Evt *)&buf.vevent); > +} > + > static void smmuv3_accel_free_veventq(SMMUv3AccelState *accel) > { > IOMMUFDVeventq *veventq = accel->veventq; > @@ -385,6 +437,8 @@ static void smmuv3_accel_free_veventq(SMMUv3AccelState > *accel) > if (!veventq) { > return; > } > + qemu_set_fd_handler(veventq->veventq_fd, NULL, NULL, NULL); > + close(veventq->veventq_fd); > iommufd_backend_free_id(accel->viommu.iommufd, veventq->veventq_id); > g_free(veventq); > accel->veventq = NULL; > @@ -427,6 +481,10 @@ bool smmuv3_accel_alloc_veventq(SMMUv3State *s, Error > **errp) > veventq->veventq_fd = veventq_fd; > veventq->viommu = &accel->viommu; > accel->veventq = veventq; > + > + /* Set up event handler for veventq fd */ > + fcntl(veventq_fd, F_SETFL, O_NONBLOCK); > + qemu_set_fd_handler(veventq_fd, smmuv3_accel_event_read, NULL, s); > return true; > } > > diff --git a/hw/arm/smmuv3-accel.h b/hw/arm/smmuv3-accel.h > index 7b0f585769..2c7c30d6a0 100644 > --- a/hw/arm/smmuv3-accel.h > +++ b/hw/arm/smmuv3-accel.h > @@ -21,6 +21,8 @@ > typedef struct SMMUv3AccelState { > IOMMUFDViommu viommu; > IOMMUFDVeventq *veventq; > + uint32_t last_event_seq; > + bool event_start; > uint32_t bypass_hwpt_id; > uint32_t abort_hwpt_id; > QLIST_HEAD(, SMMUv3AccelDevice) device_list; Thanks
Eric
