Hi Nathan,
On 4/22/26 10:43 PM, Nathan Chen wrote:
> Introduce smmuv3_accel_auto_finalise() to resolve properties that are
> set to 'auto' for accelerated SMMUv3. This helper function allows
> properties such as ats, ril, ssidsize, and oas support to be resolved
> from host IOMMU capabilities via IOMMU_GET_HW_INFO.
>
> The later commits in this series set the auto_mode flag to true when
> an accel SMMUv3 property value is explicitly set to 'auto', or if the
> property value is not set and defaults to auto mode.
>
> Setting these property values to 'auto' requires at least one
> cold-plugged device to retrieve and finalise these properties. If the
> auto_mode flag is true, register a machine_init_done notifier to
> verify this requirement and fail boot if it is not met.
>
> Hot-plugged devices into an accel SMMUv3-associated bus will re-use
> the resolved host values from the initial cold-plug.
>
> Subsequent patches will make use of this helper to resolve 'auto' to
> what is reported by host IOMMU capabilities.
>
> Suggested-by: Shameer Kolothum <[email protected]>
> Signed-off-by: Nathan Chen <[email protected]>
Reviewed-by: Eric Auger <[email protected]>
Eric
> ---
> hw/arm/smmuv3-accel.c | 43 +++++++++++++++++++++++++++++++++++++++++
> hw/arm/smmuv3-accel.h | 2 ++
> include/hw/arm/smmuv3.h | 2 ++
> 3 files changed, 47 insertions(+)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index 65c2f44880..8b3bbf3ef6 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -18,6 +18,7 @@
>
> #include "smmuv3-internal.h"
> #include "smmuv3-accel.h"
> +#include "system/system.h"
>
> /*
> * The root region aliases the global system memory, and shared_as_sysmem
> @@ -35,11 +36,32 @@ static int smmuv3_oas_bits(uint32_t oas)
> return map[oas];
> }
>
> +static void smmuv3_accel_auto_finalise(SMMUv3State *s,
> + struct iommu_hw_info_arm_smmuv3
> *info) {
> + SMMUv3AccelState *accel = s->s_accel;
> +
> + /*
> + * Return if 'auto' was not set for any accel SMMUv3 property, or
> + * if property values were already resolved from a previous call
> + * to this function (e.g. if this function was called again after
> + * VM boot during device hot plug). We do not accept new property
> + * values in this case where auto_finalised == true, and we re-use
> + * the values determined from the initial cold plug.
> + */
> + if (!accel->auto_mode || accel->auto_finalised) {
> + return;
> + }
> +
> + accel->auto_finalised = true;
> +}
> +
> static bool
> smmuv3_accel_check_hw_compatible(SMMUv3State *s,
> struct iommu_hw_info_arm_smmuv3 *info,
> Error **errp)
> {
> + smmuv3_accel_auto_finalise(s, info);
> +
> /* QEMU SMMUv3 supports both linear and 2-level stream tables */
> if (FIELD_EX32(info->idr[0], IDR0, STLEVEL) !=
> FIELD_EX32(s->idr[0], IDR0, STLEVEL)) {
> @@ -917,6 +939,22 @@ static void smmuv3_accel_as_init(SMMUv3State *s)
> address_space_init(shared_as_sysmem, &root, "smmuv3-accel-as-sysmem");
> }
>
> +static void smmuv3_machine_done(Notifier *notifier, void *data)
> +{
> + SMMUv3State *s = container_of(notifier, SMMUv3State, machine_done);
> + SMMUv3AccelState *accel = s->s_accel;
> +
> + if (!s->accel) {
> + return;
> + }
> +
> + if (accel->auto_mode && !accel->auto_finalised) {
> + error_report("arm-smmuv3 accel=on with 'auto' properties requires "
> + "at least one cold-plugged VFIO device");
> + exit(1);
> + }
> +}
> +
> void smmuv3_accel_init(SMMUv3State *s)
> {
> SMMUState *bs = ARM_SMMU(s);
> @@ -924,4 +962,9 @@ void smmuv3_accel_init(SMMUv3State *s)
> s->s_accel = g_new0(SMMUv3AccelState, 1);
> bs->iommu_ops = &smmuv3_accel_ops;
> smmuv3_accel_as_init(s);
> +
> + if (s->s_accel->auto_mode) {
> + s->machine_done.notify = smmuv3_machine_done;
> + qemu_add_machine_init_done_notifier(&s->machine_done);
> + }
> }
> diff --git a/hw/arm/smmuv3-accel.h b/hw/arm/smmuv3-accel.h
> index dba6c71de5..3c1cd55714 100644
> --- a/hw/arm/smmuv3-accel.h
> +++ b/hw/arm/smmuv3-accel.h
> @@ -26,6 +26,8 @@ typedef struct SMMUv3AccelState {
> uint32_t bypass_hwpt_id;
> uint32_t abort_hwpt_id;
> QLIST_HEAD(, SMMUv3AccelDevice) device_list;
> + bool auto_mode;
> + bool auto_finalised;
> } SMMUv3AccelState;
>
> typedef struct SMMUS1Hwpt {
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index 82f18eb090..fe0493c1aa 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -74,6 +74,8 @@ struct SMMUv3State {
> OnOffAuto ats;
> OasMode oas;
> SsidSizeMode ssidsize;
> +
> + Notifier machine_done;
> };
>
> typedef enum {
