Hi Shameer,
On 2/11/26 9:34 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().
>
> Tested-by: Nicolin Chen <[email protected]>
> Signed-off-by: Shameer Kolothum <[email protected]>
> ---
> hw/arm/smmuv3-accel.c | 62 +++++++++++++++++++++++++++++++++++++++++++
> hw/arm/smmuv3-accel.h | 2 ++
> 2 files changed, 64 insertions(+)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index d92fcb1a89..0d5dcef941 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -390,6 +390,48 @@ 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)
> +{
> + SMMUv3State *s = opaque;
> + SMMUv3AccelState *accel = s->s_accel;
> + struct {
> + struct iommufd_vevent_header hdr;
> + struct iommu_vevent_arm_smmuv3 vevent;
> + } buf;
> + uint32_t last_seq = accel->last_event_seq;
> + ssize_t bytes;
> +
> + bytes = read(accel->veventq->veventq_fd, &buf, sizeof(buf));
> + if (bytes <= 0) {
> + if (errno == EAGAIN || errno == EINTR) {
> + return;
> + }
> + error_report_once("vEVENTQ: read failed (%m)");
> + return;
> + }
> +
> + if (bytes == sizeof(buf.hdr) &&
> + (buf.hdr.flags & IOMMU_VEVENTQ_FLAG_LOST_EVENTS)) {
> + error_report_once("vEVENTQ has lost events");
in case in the future we end up with several vEVENTQs, it may be
relevant to log the queue id/type
After reading the linux uapi again, this seems to record a queue
overflow. I would replace the
"vEVENTQ has lost events" trace by "queue <type> <id> has overflowed". This
would allow differentiation with the case below.
> + accel->event_start = false;
> + return;
> + }
> + if (bytes < sizeof(buf)) {
> + error_report_once("vEVENTQ: incomplete read (%zd/%zd bytes)",
> + bytes, sizeof(buf));
> + return;
> + }
> +
> + /* Check sequence in hdr for lost events if any */
> + if (accel->event_start && (buf.hdr.sequence - last_seq != 1)) {
wonder if we need to handle any hypothetical wrap-up situation?
> + error_report_once("vEVENTQ: detected lost %u event(s)",
> + buf.hdr.sequence - last_seq - 1);
> + }
> + 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;
> @@ -397,6 +439,7 @@ 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);
> @@ -424,6 +467,7 @@ bool smmuv3_accel_alloc_veventq(SMMUv3State *s, Error
> **errp)
> IOMMUFDVeventq *veventq;
> uint32_t veventq_id;
> uint32_t veventq_fd;
> + int flags;
>
> if (!accel || !accel->viommu) {
> return true;
> @@ -445,12 +489,30 @@ bool smmuv3_accel_alloc_veventq(SMMUv3State *s, Error
> **errp)
> return false;
> }
>
> + flags = fcntl(veventq_fd, F_GETFL);
> + if (flags < 0) {
> + error_setg_errno(errp, errno, "Failed to get flags for vEVENTQ fd");
> + goto free_veventq;
> + }
> + if (fcntl(veventq_fd, F_SETFL, flags | O_NONBLOCK) < 0) {
> + error_setg_errno(errp, errno, "Failed to set O_NONBLOCK on vEVENTQ
> fd");
> + goto free_veventq;
> + }
> +
> veventq = g_new(IOMMUFDVeventq, 1);
> veventq->veventq_id = veventq_id;
> veventq->veventq_fd = veventq_fd;
> veventq->viommu = accel->viommu;
> accel->veventq = veventq;
> +
> + /* Set up event handler for veventq fd */
> + qemu_set_fd_handler(veventq_fd, smmuv3_accel_event_read, NULL, s);
> return true;
> +
> +free_veventq:
> + close(veventq_fd);
> + iommufd_backend_free_id(accel->viommu->iommufd, veventq_id);
> + return false;
> }
>
> static bool
> diff --git a/hw/arm/smmuv3-accel.h b/hw/arm/smmuv3-accel.h
> index dba6c71de5..c9c10e55c3 100644
> --- a/hw/arm/smmuv3-accel.h
> +++ b/hw/arm/smmuv3-accel.h
> @@ -23,6 +23,8 @@
> 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
