[PATCH v2 0/8] hw/arm/smmuv3-accel: Support AUTO properties

[PATCH v2 0/8] hw/arm/smmuv3-accel: Support AUTO properties

[Nathan Chen]

Hi,

This is a follow-up to the previous RFC series [0] that introduces
support for specifying 'auto' for arm-smmuv3 accelerated mode's ATS,
RIL, SSIDSIZE, and OAS feature properties. Based on feedback from the
previous mailing list discussion, this refresh only converts the
properties to the auto form, keeping the default values from
Shameer's HW-accel SMMUv3 series [1]. A future series will
introduce support for resolving the 'auto' values based on host
SMMUv3 IDR values, as well as setting per-device ATS capability.

When set to 'auto', RIL and OAS will use the defaults set from
smmuv3_init_id_regs() while ATS and SSIDSIZE will remain at the
initialized 0 value; i.e. RIL enabled, 44-bit OAS, ATS support
disabled, 0-bit SSIDSIZE.

A complete branch can be found here:
https://github.com/NathanChenNVIDIA/qemu/tree/smmuv3-accel-auto-v2

Please take a look and let me know your feedback.

Thanks,
Nathan

Changes from RFCv1:
- Remove changes that resolve the 'auto' values based on host SMMUv3
- Restore defaults values for RIL, OAS, SSIDSIZE, and ATS
- Update OasMode to accept all OAS sizes instead of only auto, 44, and
  48
- Include comment in SsidSizeMode schema clarifying enum value
  ordering
- Replace ats-enabled prop with a helper that accepts the dynamic
  casted TYPE_ARM_SMMUV3 object
- Separate out guest vs. host ATS check in
  smmuv3_accel_check_hw_compatible() to a different commit
- Document accel, RIL, OAS, SSIDSIZE, and ATS properties in
  qemu-options.hx

Testing:
Basic sanity testing was performed on an NVIDIA Grace platform with GPU
device assignment and running CUDA test apps on the guest. Additional
testing and feedback are welcome.

[0] https://lore.kernel.org/qemu-devel/20260309192119.870186-1-nathanc@nvidia.com/
[1] https://lore.kernel.org/all/20260126104342.253965-1-skolothumtho@nvidia.com/

Nathan Chen (8):
  hw/arm/smmuv3-accel: Check ATS compatibility between host and guest
  hw/arm/smmuv3-accel: Change ATS property to OnOffAuto
  hw/arm/smmuv3-accel: Change RIL property to OnOffAuto
  qdev: Add a SsidSizeMode property
  hw/arm/smmuv3-accel: Change SSIDSIZE property to SsidSizeMode
  qdev: Add an OasMode property
  hw/arm/smmuv3-accel: Change OAS property to OasMode
  qemu-options.hx: Document arm-smmuv3 device's accel properties

 hw/arm/smmuv3-accel.c                    | 42 ++++++++++++++++++----
 hw/arm/smmuv3.c                          | 38 ++++++++++----------
 hw/arm/virt-acpi-build.c                 |  2 +-
 hw/core/qdev-properties-system.c         | 27 +++++++++++++++
 include/hw/arm/smmuv3.h                  | 11 +++---
 include/hw/core/qdev-properties-system.h |  6 ++++
 qapi/misc-arm.json                       | 44 ++++++++++++++++++++++++
 qapi/pragma.json                         |  1 +
 qemu-options.hx                          | 29 +++++++++++++++-
 9 files changed, 169 insertions(+), 31 deletions(-)

-- 
2.43.0

[PATCH v2 1/8] hw/arm/smmuv3-accel: Check ATS compatibility between host and guest

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Compare the host SMMUv3 ATS support bit with the guest SMMUv3 ATS support
bit in IDR0 and fail the compatibility check if ATS support is opted as
enabled on the guest SMMUv3 when it is not supported on host SMMUv3.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/arm/smmuv3-accel.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index 17306cd04b..fe78ce69a5 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -101,6 +101,13 @@ smmuv3_accel_check_hw_compatible(SMMUv3State *s,
                    smmuv3_oas_bits(FIELD_EX32(s->idr[5], IDR5, OAS)));
         return false;
     }
+    /* Check ATS value opted is compatible with Host SMMUv3 */
+    if (FIELD_EX32(info->idr[0], IDR0, ATS) <
+                FIELD_EX32(s->idr[0], IDR0, ATS)) {
+        error_setg(errp, "Host SMMUv3 doesn't support Address Translation"
+                   " Services");
+        return false;
+    }
 
     /* QEMU SMMUv3 supports GRAN4K/GRAN16K/GRAN64K translation granules */
     if (FIELD_EX32(info->idr[5], IDR5, GRAN4K) !=
-- 
2.43.0

Re: [PATCH v2 1/8] hw/arm/smmuv3-accel: Check ATS compatibility between host and guest

[Eric Auger]

Hi Nathan, 

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Compare the host SMMUv3 ATS support bit with the guest SMMUv3 ATS support
> bit in IDR0 and fail the compatibility check if ATS support is opted as
> enabled on the guest SMMUv3 when it is not supported on host SMMUv3.

Miss
Fixes: f7f5013a55a3 ("hw/arm/smmuv3-accel: Add support for ATS")
>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index 17306cd04b..fe78ce69a5 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -101,6 +101,13 @@ smmuv3_accel_check_hw_compatible(SMMUv3State *s,
>                     smmuv3_oas_bits(FIELD_EX32(s->idr[5], IDR5, OAS)));
>          return false;
>      }
> +    /* Check ATS value opted is compatible with Host SMMUv3 */
> +    if (FIELD_EX32(info->idr[0], IDR0, ATS) <
> +                FIELD_EX32(s->idr[0], IDR0, ATS)) {
> +        error_setg(errp, "Host SMMUv3 doesn't support Address Translation"
> +                   " Services");
I think you can keep it on the same line. Checkpatch will just issue a
warning.
> +        return false;
> +    }
>  
>      /* QEMU SMMUv3 supports GRAN4K/GRAN16K/GRAN64K translation granules */
>      if (FIELD_EX32(info->idr[5], IDR5, GRAN4K) !=
Otherwise
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric

Re: [PATCH v2 1/8] hw/arm/smmuv3-accel: Check ATS compatibility between host and guest

[Nathan Chen]

Hi Eric,

On 3/16/2026 12:32 AM, Eric Auger wrote:
> Hi Nathan,
> 
> On 3/12/26 10:03 PM, Nathan Chen wrote:
>> From: Nathan Chen<nathanc@nvidia.com>
>>
>> Compare the host SMMUv3 ATS support bit with the guest SMMUv3 ATS support
>> bit in IDR0 and fail the compatibility check if ATS support is opted as
>> enabled on the guest SMMUv3 when it is not supported on host SMMUv3.
> Miss
> Fixes: f7f5013a55a3 ("hw/arm/smmuv3-accel: Add support for ATS")

I'll include this in the next refresh.
>> Signed-off-by: Nathan Chen<nathanc@nvidia.com>
>> ---
>>   hw/arm/smmuv3-accel.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
>> index 17306cd04b..fe78ce69a5 100644
>> --- a/hw/arm/smmuv3-accel.c
>> +++ b/hw/arm/smmuv3-accel.c
>> @@ -101,6 +101,13 @@ smmuv3_accel_check_hw_compatible(SMMUv3State *s,
>>                      smmuv3_oas_bits(FIELD_EX32(s->idr[5], IDR5, OAS)));
>>           return false;
>>       }
>> +    /* Check ATS value opted is compatible with Host SMMUv3 */
>> +    if (FIELD_EX32(info->idr[0], IDR0, ATS) <
>> +                FIELD_EX32(s->idr[0], IDR0, ATS)) {
>> +        error_setg(errp, "Host SMMUv3 doesn't support Address Translation"
>> +                   " Services");
> I think you can keep it on the same line. Checkpatch will just issue a
> warning.

Ok, I will put this on the same line.
>> +        return false;
>> +    }
>>   
>>       /* QEMU SMMUv3 supports GRAN4K/GRAN16K/GRAN64K translation granules */
>>       if (FIELD_EX32(info->idr[5], IDR5, GRAN4K) !=
> Otherwise
> Reviewed-by: Eric Auger<eric.auger@redhat.com>

Thanks for the feedback and R-by!

Nathan

[PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to OnOffAuto

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Change accel SMMUv3 ATS property from bool to OnOffAuto. Setting 'auto'
will result in the default value being used, i.e. 0 in IDR0 which
translates to 'off'. A future patch will implement resolution of 'auto'
value to match the host SMMUv3 ATS support.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/arm/smmuv3-accel.c    | 8 ++++++--
 hw/arm/smmuv3.c          | 9 +++++++--
 hw/arm/virt-acpi-build.c | 2 +-
 include/hw/arm/smmuv3.h  | 4 +++-
 4 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index fe78ce69a5..5d14abe307 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -827,8 +827,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
     /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
     s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
 
-    /* QEMU SMMUv3 has no ATS. Advertise ATS if opt-in by property */
-    s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, s->ats);
+    /* Only override ATS if user explicitly set ON or OFF */
+    if (s->ats == ON_OFF_AUTO_ON) {
+        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 1);
+    } else if (s->ats == ON_OFF_AUTO_OFF) {
+        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 0);
+    }
 
     /* Advertise 48-bit OAS in IDR5 when requested (default is 44 bits). */
     if (s->oas == SMMU_OAS_48BIT) {
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 068108e49b..862ca945d5 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -317,6 +317,11 @@ static void smmuv3_init_id_regs(SMMUv3State *s)
     smmuv3_accel_idr_override(s);
 }
 
+bool smmuv3_ats_enabled(SMMUv3State *s)
+{
+    return FIELD_EX32(s->idr[0], IDR0, ATS);
+}
+
 static void smmuv3_reset(SMMUv3State *s)
 {
     s->cmdq.base = deposit64(s->cmdq.base, 0, 5, SMMU_CMDQS);
@@ -1971,7 +1976,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
             error_setg(errp, "ril can only be disabled if accel=on");
             return false;
         }
-        if (s->ats) {
+        if (s->ats == ON_OFF_AUTO_ON) {
             error_setg(errp, "ats can only be enabled if accel=on");
             return false;
         }
@@ -2128,7 +2133,7 @@ static const Property smmuv3_properties[] = {
     DEFINE_PROP_UINT64("msi-gpa", SMMUv3State, msi_gpa, 0),
     /* RIL can be turned off for accel cases */
     DEFINE_PROP_BOOL("ril", SMMUv3State, ril, true),
-    DEFINE_PROP_BOOL("ats", SMMUv3State, ats, false),
+    DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
     DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
     DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
 };
diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 719d2f994e..591cfc993c 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -402,7 +402,7 @@ static int iort_smmuv3_devices(Object *obj, void *opaque)
 
     bus = PCI_BUS(object_property_get_link(obj, "primary-bus", &error_abort));
     sdev.accel = object_property_get_bool(obj, "accel", &error_abort);
-    sdev.ats = object_property_get_bool(obj, "ats", &error_abort);
+    sdev.ats = smmuv3_ats_enabled(ARM_SMMUV3(obj));
     pbus = PLATFORM_BUS_DEVICE(vms->platform_bus_dev);
     sbdev = SYS_BUS_DEVICE(obj);
     sdev.base = platform_bus_get_mmio_addr(pbus, sbdev, 0);
diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
index 26b2fc42fd..ce51a5b9b4 100644
--- a/include/hw/arm/smmuv3.h
+++ b/include/hw/arm/smmuv3.h
@@ -70,7 +70,7 @@ struct SMMUv3State {
     uint64_t msi_gpa;
     Error *migration_blocker;
     bool ril;
-    bool ats;
+    OnOffAuto ats;
     uint8_t oas;
     uint8_t ssidsize;
 };
@@ -91,6 +91,8 @@ struct SMMUv3Class {
     ResettablePhases parent_phases;
 };
 
+bool smmuv3_ats_enabled(struct SMMUv3State *s);
+
 #define TYPE_ARM_SMMUV3   "arm-smmuv3"
 OBJECT_DECLARE_TYPE(SMMUv3State, SMMUv3Class, ARM_SMMUV3)
 
-- 
2.43.0

Re: [PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to OnOffAuto

[Eric Auger]

Hi Nathan,

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Change accel SMMUv3 ATS property from bool to OnOffAuto. Setting 'auto'
> will result in the default value being used, i.e. 0 in IDR0 which
> translates to 'off'. A future patch will implement resolution of 'auto'
> value to match the host SMMUv3 ATS support.

 i.e. 0 in IDR0 which translates to 'off': this is unclear to me what you want to say.

I would clearly state here that at the moment the auto value is not implemented. This is just to get the property right and do not break JSON/QMP when getting the auto mode introduced. Also I think you want to enforce that in the code, ie. the end user is not trying to set to AUTO.

Thanks

Eric

>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c    | 8 ++++++--
>  hw/arm/smmuv3.c          | 9 +++++++--
>  hw/arm/virt-acpi-build.c | 2 +-
>  include/hw/arm/smmuv3.h  | 4 +++-
>  4 files changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index fe78ce69a5..5d14abe307 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -827,8 +827,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>      /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
>      s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
>  
> -    /* QEMU SMMUv3 has no ATS. Advertise ATS if opt-in by property */
> -    s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, s->ats);
> +    /* Only override ATS if user explicitly set ON or OFF */
> +    if (s->ats == ON_OFF_AUTO_ON) {
> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 1);
> +    } else if (s->ats == ON_OFF_AUTO_OFF) {
> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 0);
> +    }
>  
>      /* Advertise 48-bit OAS in IDR5 when requested (default is 44 bits). */
>      if (s->oas == SMMU_OAS_48BIT) {
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 068108e49b..862ca945d5 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -317,6 +317,11 @@ static void smmuv3_init_id_regs(SMMUv3State *s)
>      smmuv3_accel_idr_override(s);
>  }
>  
> +bool smmuv3_ats_enabled(SMMUv3State *s)
> +{
> +    return FIELD_EX32(s->idr[0], IDR0, ATS);
> +}
> +
>  static void smmuv3_reset(SMMUv3State *s)
>  {
>      s->cmdq.base = deposit64(s->cmdq.base, 0, 5, SMMU_CMDQS);
> @@ -1971,7 +1976,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>              error_setg(errp, "ril can only be disabled if accel=on");
>              return false;
>          }
> -        if (s->ats) {
> +        if (s->ats == ON_OFF_AUTO_ON) {
>              error_setg(errp, "ats can only be enabled if accel=on");
>              return false;
>          }
> @@ -2128,7 +2133,7 @@ static const Property smmuv3_properties[] = {
>      DEFINE_PROP_UINT64("msi-gpa", SMMUv3State, msi_gpa, 0),
>      /* RIL can be turned off for accel cases */
>      DEFINE_PROP_BOOL("ril", SMMUv3State, ril, true),
> -    DEFINE_PROP_BOOL("ats", SMMUv3State, ats, false),
> +    DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
>      DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
>      DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
>  };
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 719d2f994e..591cfc993c 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -402,7 +402,7 @@ static int iort_smmuv3_devices(Object *obj, void *opaque)
>  
>      bus = PCI_BUS(object_property_get_link(obj, "primary-bus", &error_abort));
>      sdev.accel = object_property_get_bool(obj, "accel", &error_abort);
> -    sdev.ats = object_property_get_bool(obj, "ats", &error_abort);
> +    sdev.ats = smmuv3_ats_enabled(ARM_SMMUV3(obj));
>      pbus = PLATFORM_BUS_DEVICE(vms->platform_bus_dev);
>      sbdev = SYS_BUS_DEVICE(obj);
>      sdev.base = platform_bus_get_mmio_addr(pbus, sbdev, 0);
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index 26b2fc42fd..ce51a5b9b4 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -70,7 +70,7 @@ struct SMMUv3State {
>      uint64_t msi_gpa;
>      Error *migration_blocker;
>      bool ril;
> -    bool ats;
> +    OnOffAuto ats;
>      uint8_t oas;
>      uint8_t ssidsize;
>  };
> @@ -91,6 +91,8 @@ struct SMMUv3Class {
>      ResettablePhases parent_phases;
>  };
>  
> +bool smmuv3_ats_enabled(struct SMMUv3State *s);
> +
>  #define TYPE_ARM_SMMUV3   "arm-smmuv3"
>  OBJECT_DECLARE_TYPE(SMMUv3State, SMMUv3Class, ARM_SMMUV3)
>  

Re: [PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to OnOffAuto

[Nathan Chen]

Hi Eric,

On 3/16/2026 12:38 AM, Eric Auger wrote:
> Hi Nathan,
> 
> On 3/12/26 10:03 PM, Nathan Chen wrote:
>> From: Nathan Chen<nathanc@nvidia.com>
>>
>> Change accel SMMUv3 ATS property from bool to OnOffAuto. Setting 'auto'
>> will result in the default value being used, i.e. 0 in IDR0 which
>> translates to 'off'. A future patch will implement resolution of 'auto'
>> value to match the host SMMUv3 ATS support.
>   i.e. 0 in IDR0 which translates to 'off': this is unclear to me what you want to say.
> 
> I would clearly state here that at the moment the auto value is not implemented. This is just to get the property right and do not break JSON/QMP when getting the auto mode introduced. Also I think you want to enforce that in the code, ie. the end user is not trying to set to AUTO.

That makes sense, in the next refresh I will enforce not setting auto 
for these properties and reflect that in the commit messages.

Thanks,
Nathan

Re: [PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to OnOffAuto

[Eric Auger]

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Change accel SMMUv3 ATS property from bool to OnOffAuto. Setting 'auto'
> will result in the default value being used, i.e. 0 in IDR0 which
> translates to 'off'. A future patch will implement resolution of 'auto'
> value to match the host SMMUv3 ATS support.

You may also add a Fixes tag

Eric
>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c    | 8 ++++++--
>  hw/arm/smmuv3.c          | 9 +++++++--
>  hw/arm/virt-acpi-build.c | 2 +-
>  include/hw/arm/smmuv3.h  | 4 +++-
>  4 files changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index fe78ce69a5..5d14abe307 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -827,8 +827,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>      /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
>      s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
>  
> -    /* QEMU SMMUv3 has no ATS. Advertise ATS if opt-in by property */
> -    s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, s->ats);
> +    /* Only override ATS if user explicitly set ON or OFF */
> +    if (s->ats == ON_OFF_AUTO_ON) {
> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 1);
> +    } else if (s->ats == ON_OFF_AUTO_OFF) {
> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 0);
> +    }
>  
>      /* Advertise 48-bit OAS in IDR5 when requested (default is 44 bits). */
>      if (s->oas == SMMU_OAS_48BIT) {
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 068108e49b..862ca945d5 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -317,6 +317,11 @@ static void smmuv3_init_id_regs(SMMUv3State *s)
>      smmuv3_accel_idr_override(s);
>  }
>  
> +bool smmuv3_ats_enabled(SMMUv3State *s)
> +{
> +    return FIELD_EX32(s->idr[0], IDR0, ATS);
> +}
> +
>  static void smmuv3_reset(SMMUv3State *s)
>  {
>      s->cmdq.base = deposit64(s->cmdq.base, 0, 5, SMMU_CMDQS);
> @@ -1971,7 +1976,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>              error_setg(errp, "ril can only be disabled if accel=on");
>              return false;
>          }
> -        if (s->ats) {
> +        if (s->ats == ON_OFF_AUTO_ON) {
>              error_setg(errp, "ats can only be enabled if accel=on");
>              return false;
>          }
> @@ -2128,7 +2133,7 @@ static const Property smmuv3_properties[] = {
>      DEFINE_PROP_UINT64("msi-gpa", SMMUv3State, msi_gpa, 0),
>      /* RIL can be turned off for accel cases */
>      DEFINE_PROP_BOOL("ril", SMMUv3State, ril, true),
> -    DEFINE_PROP_BOOL("ats", SMMUv3State, ats, false),
> +    DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
>      DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
>      DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
>  };
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 719d2f994e..591cfc993c 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -402,7 +402,7 @@ static int iort_smmuv3_devices(Object *obj, void *opaque)
>  
>      bus = PCI_BUS(object_property_get_link(obj, "primary-bus", &error_abort));
>      sdev.accel = object_property_get_bool(obj, "accel", &error_abort);
> -    sdev.ats = object_property_get_bool(obj, "ats", &error_abort);
> +    sdev.ats = smmuv3_ats_enabled(ARM_SMMUV3(obj));
>      pbus = PLATFORM_BUS_DEVICE(vms->platform_bus_dev);
>      sbdev = SYS_BUS_DEVICE(obj);
>      sdev.base = platform_bus_get_mmio_addr(pbus, sbdev, 0);
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index 26b2fc42fd..ce51a5b9b4 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -70,7 +70,7 @@ struct SMMUv3State {
>      uint64_t msi_gpa;
>      Error *migration_blocker;
>      bool ril;
> -    bool ats;
> +    OnOffAuto ats;
>      uint8_t oas;
>      uint8_t ssidsize;
>  };
> @@ -91,6 +91,8 @@ struct SMMUv3Class {
>      ResettablePhases parent_phases;
>  };
>  
> +bool smmuv3_ats_enabled(struct SMMUv3State *s);
> +
>  #define TYPE_ARM_SMMUV3   "arm-smmuv3"
>  OBJECT_DECLARE_TYPE(SMMUv3State, SMMUv3Class, ARM_SMMUV3)
>  

RE: [PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to OnOffAuto

[Shameer Kolothum Thodi]

> -----Original Message-----
> From: Nathan Chen <nathanc@nvidia.com>
> Sent: 12 March 2026 21:03
> To: qemu-devel@nongnu.org; qemu-arm@nongnu.org
> Cc: Eric Auger <eric.auger@redhat.com>; Peter Maydell
> <peter.maydell@linaro.org>; Michael S . Tsirkin <mst@redhat.com>; Igor
> Mammedov <imammedo@redhat.com>; Ani Sinha <anisinha@redhat.com>;
> Shannon Zhao <shannon.zhaosl@gmail.com>; Paolo Bonzini
> <pbonzini@redhat.com>; Daniel P . Berrangé <berrange@redhat.com>;
> Eduardo Habkost <eduardo@habkost.net>; Eric Blake <eblake@redhat.com>;
> Markus Armbruster <armbru@redhat.com>; Shameer Kolothum Thodi
> <skolothumtho@nvidia.com>; Nicolin Chen <nicolinc@nvidia.com>; Matt
> Ochs <mochs@nvidia.com>; Nathan Chen <nathanc@nvidia.com>
> Subject: [PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to
> OnOffAuto
> 
> From: Nathan Chen <nathanc@nvidia.com>
> 
> Change accel SMMUv3 ATS property from bool to OnOffAuto. Setting 'auto'
> will result in the default value being used, i.e. 0 in IDR0 which
> translates to 'off'. A future patch will implement resolution of 'auto'
> value to match the host SMMUv3 ATS support.
> 
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c    | 8 ++++++--
>  hw/arm/smmuv3.c          | 9 +++++++--
>  hw/arm/virt-acpi-build.c | 2 +-
>  include/hw/arm/smmuv3.h  | 4 +++-
>  4 files changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index fe78ce69a5..5d14abe307 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -827,8 +827,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>      /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
>      s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
> 
> -    /* QEMU SMMUv3 has no ATS. Advertise ATS if opt-in by property */
> -    s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, s->ats);
> +    /* Only override ATS if user explicitly set ON or OFF */
> +    if (s->ats == ON_OFF_AUTO_ON) {
> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 1);
> +    } else if (s->ats == ON_OFF_AUTO_OFF) {
> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 0);
> +    }

The else condition is not required as ATS will be set to 0 by default.

Thanks,
Shameer

> 
>      /* Advertise 48-bit OAS in IDR5 when requested (default is 44 bits). */
>      if (s->oas == SMMU_OAS_48BIT) {
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 068108e49b..862ca945d5 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -317,6 +317,11 @@ static void smmuv3_init_id_regs(SMMUv3State *s)
>      smmuv3_accel_idr_override(s);
>  }
> 
> +bool smmuv3_ats_enabled(SMMUv3State *s)
> +{
> +    return FIELD_EX32(s->idr[0], IDR0, ATS);
> +}
> +
>  static void smmuv3_reset(SMMUv3State *s)
>  {
>      s->cmdq.base = deposit64(s->cmdq.base, 0, 5, SMMU_CMDQS);
> @@ -1971,7 +1976,7 @@ static bool
> smmu_validate_property(SMMUv3State *s, Error **errp)
>              error_setg(errp, "ril can only be disabled if accel=on");
>              return false;
>          }
> -        if (s->ats) {
> +        if (s->ats == ON_OFF_AUTO_ON) {
>              error_setg(errp, "ats can only be enabled if accel=on");
>              return false;
>          }
> @@ -2128,7 +2133,7 @@ static const Property smmuv3_properties[] = {
>      DEFINE_PROP_UINT64("msi-gpa", SMMUv3State, msi_gpa, 0),
>      /* RIL can be turned off for accel cases */
>      DEFINE_PROP_BOOL("ril", SMMUv3State, ril, true),
> -    DEFINE_PROP_BOOL("ats", SMMUv3State, ats, false),
> +    DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats,
> ON_OFF_AUTO_OFF),
>      DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
>      DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
>  };
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 719d2f994e..591cfc993c 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -402,7 +402,7 @@ static int iort_smmuv3_devices(Object *obj, void
> *opaque)
> 
>      bus = PCI_BUS(object_property_get_link(obj, "primary-bus",
> &error_abort));
>      sdev.accel = object_property_get_bool(obj, "accel", &error_abort);
> -    sdev.ats = object_property_get_bool(obj, "ats", &error_abort);
> +    sdev.ats = smmuv3_ats_enabled(ARM_SMMUV3(obj));
>      pbus = PLATFORM_BUS_DEVICE(vms->platform_bus_dev);
>      sbdev = SYS_BUS_DEVICE(obj);
>      sdev.base = platform_bus_get_mmio_addr(pbus, sbdev, 0);
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index 26b2fc42fd..ce51a5b9b4 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -70,7 +70,7 @@ struct SMMUv3State {
>      uint64_t msi_gpa;
>      Error *migration_blocker;
>      bool ril;
> -    bool ats;
> +    OnOffAuto ats;
>      uint8_t oas;
>      uint8_t ssidsize;
>  };
> @@ -91,6 +91,8 @@ struct SMMUv3Class {
>      ResettablePhases parent_phases;
>  };
> 
> +bool smmuv3_ats_enabled(struct SMMUv3State *s);
> +
>  #define TYPE_ARM_SMMUV3   "arm-smmuv3"
>  OBJECT_DECLARE_TYPE(SMMUv3State, SMMUv3Class, ARM_SMMUV3)
> 
> --
> 2.43.0

Re: [PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to OnOffAuto

[Nathan Chen]

On 3/16/2026 1:48 AM, Shameer Kolothum Thodi wrote:
> 
>> -----Original Message-----
>> From: Nathan Chen<nathanc@nvidia.com>
>> Sent: 12 March 2026 21:03
>> To:qemu-devel@nongnu.org;qemu-arm@nongnu.org
>> Cc: Eric Auger<eric.auger@redhat.com>; Peter Maydell
>> <peter.maydell@linaro.org>; Michael S . Tsirkin<mst@redhat.com>; Igor
>> Mammedov<imammedo@redhat.com>; Ani Sinha<anisinha@redhat.com>;
>> Shannon Zhao<shannon.zhaosl@gmail.com>; Paolo Bonzini
>> <pbonzini@redhat.com>; Daniel P . Berrangé<berrange@redhat.com>;
>> Eduardo Habkost<eduardo@habkost.net>; Eric Blake<eblake@redhat.com>;
>> Markus Armbruster<armbru@redhat.com>; Shameer Kolothum Thodi
>> <skolothumtho@nvidia.com>; Nicolin Chen<nicolinc@nvidia.com>; Matt
>> Ochs<mochs@nvidia.com>; Nathan Chen<nathanc@nvidia.com>
>> Subject: [PATCH v2 2/8] hw/arm/smmuv3-accel: Change ATS property to
>> OnOffAuto
>>
>> From: Nathan Chen<nathanc@nvidia.com>
>>
>> Change accel SMMUv3 ATS property from bool to OnOffAuto. Setting 'auto'
>> will result in the default value being used, i.e. 0 in IDR0 which
>> translates to 'off'. A future patch will implement resolution of 'auto'
>> value to match the host SMMUv3 ATS support.
>>
>> Signed-off-by: Nathan Chen<nathanc@nvidia.com>
>> ---
>>   hw/arm/smmuv3-accel.c    | 8 ++++++--
>>   hw/arm/smmuv3.c          | 9 +++++++--
>>   hw/arm/virt-acpi-build.c | 2 +-
>>   include/hw/arm/smmuv3.h  | 4 +++-
>>   4 files changed, 17 insertions(+), 6 deletions(-)
>>
>> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
>> index fe78ce69a5..5d14abe307 100644
>> --- a/hw/arm/smmuv3-accel.c
>> +++ b/hw/arm/smmuv3-accel.c
>> @@ -827,8 +827,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>>       /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
>>       s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
>>
>> -    /* QEMU SMMUv3 has no ATS. Advertise ATS if opt-in by property */
>> -    s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, s->ats);
>> +    /* Only override ATS if user explicitly set ON or OFF */
>> +    if (s->ats == ON_OFF_AUTO_ON) {
>> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 1);
>> +    } else if (s->ats == ON_OFF_AUTO_OFF) {
>> +        s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS, 0);
>> +    }
> The else condition is not required as ATS will be set to 0 by default.

I see, I will remove the else condition here.

Thanks,
Nathan

[PATCH v2 3/8] hw/arm/smmuv3-accel: Change RIL property to OnOffAuto

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Change accel SMMUv3 RIL property from bool to OnOffAuto. Setting 'auto'
will use the default set in smmuv3_init_id_regs(), i.e. 1 in IDR3 which
translates to 'on'. A future patch will implement resolution of 'auto'
value to match the host SMMUv3 RIL support.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/arm/smmuv3-accel.c   | 8 ++++++--
 hw/arm/smmuv3.c         | 4 ++--
 include/hw/arm/smmuv3.h | 2 +-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index 5d14abe307..6f44fd3469 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -824,8 +824,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
         return;
     }
 
-    /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
-    s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
+    /* Only override RIL if user explicitly set ON or OFF */
+    if (s->ril == ON_OFF_AUTO_ON) {
+        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 1);
+    } else if (s->ril == ON_OFF_AUTO_OFF) {
+        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 0);
+    }
 
     /* Only override ATS if user explicitly set ON or OFF */
     if (s->ats == ON_OFF_AUTO_ON) {
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 862ca945d5..acbd9d3ffe 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -1972,7 +1972,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
 #endif
 
     if (!s->accel) {
-        if (!s->ril) {
+        if (s->ril == ON_OFF_AUTO_OFF) {
             error_setg(errp, "ril can only be disabled if accel=on");
             return false;
         }
@@ -2132,7 +2132,7 @@ static const Property smmuv3_properties[] = {
     /* GPA of MSI doorbell, for SMMUv3 accel use. */
     DEFINE_PROP_UINT64("msi-gpa", SMMUv3State, msi_gpa, 0),
     /* RIL can be turned off for accel cases */
-    DEFINE_PROP_BOOL("ril", SMMUv3State, ril, true),
+    DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril, ON_OFF_AUTO_ON),
     DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
     DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
     DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
index ce51a5b9b4..c35e599bbc 100644
--- a/include/hw/arm/smmuv3.h
+++ b/include/hw/arm/smmuv3.h
@@ -69,7 +69,7 @@ struct SMMUv3State {
     struct SMMUv3AccelState *s_accel;
     uint64_t msi_gpa;
     Error *migration_blocker;
-    bool ril;
+    OnOffAuto ril;
     OnOffAuto ats;
     uint8_t oas;
     uint8_t ssidsize;
-- 
2.43.0

Re: [PATCH v2 3/8] hw/arm/smmuv3-accel: Change RIL property to OnOffAuto

[Eric Auger]

Hi Nathan,

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Change accel SMMUv3 RIL property from bool to OnOffAuto. Setting 'auto'
> will use the default set in smmuv3_init_id_regs(), i.e. 1 in IDR3 which
> translates to 'on'. A future patch will implement resolution of 'auto'
> value to match the host SMMUv3 RIL support.

Please a check to test the AUTO value is not set at the moment.

Add the Fixes tag too. Otherwise looks good.

Eric
>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c   | 8 ++++++--
>  hw/arm/smmuv3.c         | 4 ++--
>  include/hw/arm/smmuv3.h | 2 +-
>  3 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index 5d14abe307..6f44fd3469 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -824,8 +824,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>          return;
>      }
>  
> -    /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
> -    s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
> +    /* Only override RIL if user explicitly set ON or OFF */
> +    if (s->ril == ON_OFF_AUTO_ON) {
> +        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 1);
> +    } else if (s->ril == ON_OFF_AUTO_OFF) {
> +        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 0);
> +    }
>  
>      /* Only override ATS if user explicitly set ON or OFF */
>      if (s->ats == ON_OFF_AUTO_ON) {
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 862ca945d5..acbd9d3ffe 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -1972,7 +1972,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>  #endif
>  
>      if (!s->accel) {
> -        if (!s->ril) {
> +        if (s->ril == ON_OFF_AUTO_OFF) {
>              error_setg(errp, "ril can only be disabled if accel=on");
>              return false;
>          }
> @@ -2132,7 +2132,7 @@ static const Property smmuv3_properties[] = {
>      /* GPA of MSI doorbell, for SMMUv3 accel use. */
>      DEFINE_PROP_UINT64("msi-gpa", SMMUv3State, msi_gpa, 0),
>      /* RIL can be turned off for accel cases */
> -    DEFINE_PROP_BOOL("ril", SMMUv3State, ril, true),
> +    DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril, ON_OFF_AUTO_ON),
>      DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
>      DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
>      DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index ce51a5b9b4..c35e599bbc 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -69,7 +69,7 @@ struct SMMUv3State {
>      struct SMMUv3AccelState *s_accel;
>      uint64_t msi_gpa;
>      Error *migration_blocker;
> -    bool ril;
> +    OnOffAuto ril;
>      OnOffAuto ats;
>      uint8_t oas;
>      uint8_t ssidsize;

RE: [PATCH v2 3/8] hw/arm/smmuv3-accel: Change RIL property to OnOffAuto

[Shameer Kolothum Thodi]

> -----Original Message-----
> From: Nathan Chen <nathanc@nvidia.com>
> Sent: 12 March 2026 21:03
> To: qemu-devel@nongnu.org; qemu-arm@nongnu.org
> Cc: Eric Auger <eric.auger@redhat.com>; Peter Maydell
> <peter.maydell@linaro.org>; Michael S . Tsirkin <mst@redhat.com>; Igor
> Mammedov <imammedo@redhat.com>; Ani Sinha <anisinha@redhat.com>;
> Shannon Zhao <shannon.zhaosl@gmail.com>; Paolo Bonzini
> <pbonzini@redhat.com>; Daniel P . Berrangé <berrange@redhat.com>;
> Eduardo Habkost <eduardo@habkost.net>; Eric Blake <eblake@redhat.com>;
> Markus Armbruster <armbru@redhat.com>; Shameer Kolothum Thodi
> <skolothumtho@nvidia.com>; Nicolin Chen <nicolinc@nvidia.com>; Matt
> Ochs <mochs@nvidia.com>; Nathan Chen <nathanc@nvidia.com>
> Subject: [PATCH v2 3/8] hw/arm/smmuv3-accel: Change RIL property to
> OnOffAuto
> 
> From: Nathan Chen <nathanc@nvidia.com>
> 
> Change accel SMMUv3 RIL property from bool to OnOffAuto. Setting 'auto'
> will use the default set in smmuv3_init_id_regs(), i.e. 1 in IDR3 which
> translates to 'on'. A future patch will implement resolution of 'auto'
> value to match the host SMMUv3 RIL support.
> 
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c   | 8 ++++++--
>  hw/arm/smmuv3.c         | 4 ++--
>  include/hw/arm/smmuv3.h | 2 +-
>  3 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index 5d14abe307..6f44fd3469 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -824,8 +824,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>          return;
>      }
> 
> -    /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
> -    s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
> +    /* Only override RIL if user explicitly set ON or OFF */
> +    if (s->ril == ON_OFF_AUTO_ON) {
> +        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 1);
> +    } else if (s->ril == ON_OFF_AUTO_OFF) {
> +        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 0);
> +    }

Same here. We only need override if RIL is explicitly OFF.

Thanks,
Shameer
> 
>      /* Only override ATS if user explicitly set ON or OFF */
>      if (s->ats == ON_OFF_AUTO_ON) {
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 862ca945d5..acbd9d3ffe 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -1972,7 +1972,7 @@ static bool
> smmu_validate_property(SMMUv3State *s, Error **errp)
>  #endif
> 
>      if (!s->accel) {
> -        if (!s->ril) {
> +        if (s->ril == ON_OFF_AUTO_OFF) {
>              error_setg(errp, "ril can only be disabled if accel=on");
>              return false;
>          }
> @@ -2132,7 +2132,7 @@ static const Property smmuv3_properties[] = {
>      /* GPA of MSI doorbell, for SMMUv3 accel use. */
>      DEFINE_PROP_UINT64("msi-gpa", SMMUv3State, msi_gpa, 0),
>      /* RIL can be turned off for accel cases */
> -    DEFINE_PROP_BOOL("ril", SMMUv3State, ril, true),
> +    DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril,
> ON_OFF_AUTO_ON),
>      DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats,
> ON_OFF_AUTO_OFF),
>      DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
>      DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index ce51a5b9b4..c35e599bbc 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -69,7 +69,7 @@ struct SMMUv3State {
>      struct SMMUv3AccelState *s_accel;
>      uint64_t msi_gpa;
>      Error *migration_blocker;
> -    bool ril;
> +    OnOffAuto ril;
>      OnOffAuto ats;
>      uint8_t oas;
>      uint8_t ssidsize;
> --
> 2.43.0

Re: [PATCH v2 3/8] hw/arm/smmuv3-accel: Change RIL property to OnOffAuto

[Nathan Chen]

On 3/16/2026 1:50 AM, Shameer Kolothum Thodi wrote:
> 
>> -----Original Message-----
>> From: Nathan Chen<nathanc@nvidia.com>
>> Sent: 12 March 2026 21:03
>> To:qemu-devel@nongnu.org;qemu-arm@nongnu.org
>> Cc: Eric Auger<eric.auger@redhat.com>; Peter Maydell
>> <peter.maydell@linaro.org>; Michael S . Tsirkin<mst@redhat.com>; Igor
>> Mammedov<imammedo@redhat.com>; Ani Sinha<anisinha@redhat.com>;
>> Shannon Zhao<shannon.zhaosl@gmail.com>; Paolo Bonzini
>> <pbonzini@redhat.com>; Daniel P . Berrangé<berrange@redhat.com>;
>> Eduardo Habkost<eduardo@habkost.net>; Eric Blake<eblake@redhat.com>;
>> Markus Armbruster<armbru@redhat.com>; Shameer Kolothum Thodi
>> <skolothumtho@nvidia.com>; Nicolin Chen<nicolinc@nvidia.com>; Matt
>> Ochs<mochs@nvidia.com>; Nathan Chen<nathanc@nvidia.com>
>> Subject: [PATCH v2 3/8] hw/arm/smmuv3-accel: Change RIL property to
>> OnOffAuto
>>
>> From: Nathan Chen<nathanc@nvidia.com>
>>
>> Change accel SMMUv3 RIL property from bool to OnOffAuto. Setting 'auto'
>> will use the default set in smmuv3_init_id_regs(), i.e. 1 in IDR3 which
>> translates to 'on'. A future patch will implement resolution of 'auto'
>> value to match the host SMMUv3 RIL support.
>>
>> Signed-off-by: Nathan Chen<nathanc@nvidia.com>
>> ---
>>   hw/arm/smmuv3-accel.c   | 8 ++++++--
>>   hw/arm/smmuv3.c         | 4 ++--
>>   include/hw/arm/smmuv3.h | 2 +-
>>   3 files changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
>> index 5d14abe307..6f44fd3469 100644
>> --- a/hw/arm/smmuv3-accel.c
>> +++ b/hw/arm/smmuv3-accel.c
>> @@ -824,8 +824,12 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>>           return;
>>       }
>>
>> -    /* By default QEMU SMMUv3 has RIL. Update IDR3 if user has disabled it */
>> -    s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, s->ril);
>> +    /* Only override RIL if user explicitly set ON or OFF */
>> +    if (s->ril == ON_OFF_AUTO_ON) {
>> +        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 1);
>> +    } else if (s->ril == ON_OFF_AUTO_OFF) {
>> +        s->idr[3] = FIELD_DP32(s->idr[3], IDR3, RIL, 0);
>> +    }
> Same here. We only need override if RIL is explicitly OFF.

Ok, I will remove the condition for setting it to ON.

Thanks,
Nathan

[PATCH v2 4/8] qdev: Add a SsidSizeMode property

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Introduce a new enum type property allowing to set a Substream ID size
for HW-accelerated smmuv3. Values are auto and 0..20. The auto value
allows SSID size property to be derived from host IOMMU capabilities.
A value of 0 disables SubstreamID, while non-zero values specify the
SSID size in bits.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/core/qdev-properties-system.c         | 14 ++++++++++++++
 include/hw/core/qdev-properties-system.h |  3 +++
 qapi/misc-arm.json                       | 16 ++++++++++++++++
 qapi/pragma.json                         |  1 +
 4 files changed, 34 insertions(+)

diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index a402321f42..4aca1d4326 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -18,6 +18,7 @@
 #include "qapi/qapi-types-block.h"
 #include "qapi/qapi-types-machine.h"
 #include "qapi/qapi-types-migration.h"
+#include "qapi/qapi-types-misc-arm.h"
 #include "qapi/qapi-visit-virtio.h"
 #include "qapi/qmp/qerror.h"
 #include "qemu/ctype.h"
@@ -723,6 +724,19 @@ const PropertyInfo qdev_prop_zero_page_detection = {
     .set_default_value = qdev_propinfo_set_default_value_enum,
 };
 
+/* --- SsidSizeMode --- */
+
+QEMU_BUILD_BUG_ON(sizeof(SsidSizeMode) != sizeof(int));
+
+const PropertyInfo qdev_prop_ssidsize_mode = {
+    .type = "SsidSizeMode",
+    .description = "ssidsize mode: auto, 0-20",
+    .enum_table = &SsidSizeMode_lookup,
+    .get = qdev_propinfo_get_enum,
+    .set = qdev_propinfo_set_enum,
+    .set_default_value = qdev_propinfo_set_default_value_enum,
+};
+
 /* --- Reserved Region --- */
 
 /*
diff --git a/include/hw/core/qdev-properties-system.h b/include/hw/core/qdev-properties-system.h
index ec21732ce5..4708885164 100644
--- a/include/hw/core/qdev-properties-system.h
+++ b/include/hw/core/qdev-properties-system.h
@@ -14,6 +14,7 @@ extern const PropertyInfo qdev_prop_multifd_compression;
 extern const PropertyInfo qdev_prop_mig_mode;
 extern const PropertyInfo qdev_prop_granule_mode;
 extern const PropertyInfo qdev_prop_zero_page_detection;
+extern const PropertyInfo qdev_prop_ssidsize_mode;
 extern const PropertyInfo qdev_prop_losttickpolicy;
 extern const PropertyInfo qdev_prop_blockdev_on_error;
 extern const PropertyInfo qdev_prop_bios_chs_trans;
@@ -61,6 +62,8 @@ extern const PropertyInfo qdev_prop_virtio_gpu_output_list;
 #define DEFINE_PROP_ZERO_PAGE_DETECTION(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_zero_page_detection, \
                        ZeroPageDetection)
+#define DEFINE_PROP_SSIDSIZE_MODE(_n, _s, _f, _d) \
+    DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_ssidsize_mode, SsidSizeMode)
 #define DEFINE_PROP_LOSTTICKPOLICY(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_losttickpolicy, \
                         LostTickPolicy)
diff --git a/qapi/misc-arm.json b/qapi/misc-arm.json
index f921d740f1..76ea0a09fa 100644
--- a/qapi/misc-arm.json
+++ b/qapi/misc-arm.json
@@ -45,3 +45,19 @@
 #                     { "version": 3, "emulated": false, "kernel": true } ] }
 ##
 { 'command': 'query-gic-capabilities', 'returns': ['GICCapability'] }
+
+##
+# @SsidSizeMode:
+#
+# SMMUv3 SubstreamID size configuration mode.
+#
+# @auto: derive from host IOMMU capabilities
+#
+# Values 0-20: SSIDSIZE value in bits.  0 disables SubstreamID.
+#
+# Since: 11.0
+##
+{ 'enum': 'SsidSizeMode',
+  'data': [ 'auto', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+            '10', '11', '12', '13', '14', '15', '16', '17', '18',
+            '19', '20' ] } # order matters, see ssid_size_mode_auto()
diff --git a/qapi/pragma.json b/qapi/pragma.json
index 193bc39059..24aebbe8f5 100644
--- a/qapi/pragma.json
+++ b/qapi/pragma.json
@@ -68,6 +68,7 @@
         'S390CpuEntitlement',
         'S390CpuPolarization',
         'S390CpuState',
+        'SsidSizeMode',
         'String',
         'StringWrapper',
         'SysEmuTarget',
-- 
2.43.0

Re: [PATCH v2 4/8] qdev: Add a SsidSizeMode property

[Eric Auger]

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Introduce a new enum type property allowing to set a Substream ID size
> for HW-accelerated smmuv3. Values are auto and 0..20. The auto value
> allows SSID size property to be derived from host IOMMU capabilities.
> A value of 0 disables SubstreamID, while non-zero values specify the
> SSID size in bits.
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/core/qdev-properties-system.c         | 14 ++++++++++++++
>  include/hw/core/qdev-properties-system.h |  3 +++
>  qapi/misc-arm.json                       | 16 ++++++++++++++++
>  qapi/pragma.json                         |  1 +
>  4 files changed, 34 insertions(+)
>
> diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
> index a402321f42..4aca1d4326 100644
> --- a/hw/core/qdev-properties-system.c
> +++ b/hw/core/qdev-properties-system.c
> @@ -18,6 +18,7 @@
>  #include "qapi/qapi-types-block.h"
>  #include "qapi/qapi-types-machine.h"
>  #include "qapi/qapi-types-migration.h"
> +#include "qapi/qapi-types-misc-arm.h"
>  #include "qapi/qapi-visit-virtio.h"
>  #include "qapi/qmp/qerror.h"
>  #include "qemu/ctype.h"
> @@ -723,6 +724,19 @@ const PropertyInfo qdev_prop_zero_page_detection = {
>      .set_default_value = qdev_propinfo_set_default_value_enum,
>  };
>  
> +/* --- SsidSizeMode --- */
> +
> +QEMU_BUILD_BUG_ON(sizeof(SsidSizeMode) != sizeof(int));
> +
> +const PropertyInfo qdev_prop_ssidsize_mode = {
> +    .type = "SsidSizeMode",
> +    .description = "ssidsize mode: auto, 0-20",
> +    .enum_table = &SsidSizeMode_lookup,
> +    .get = qdev_propinfo_get_enum,
> +    .set = qdev_propinfo_set_enum,
> +    .set_default_value = qdev_propinfo_set_default_value_enum,
> +};
> +
>  /* --- Reserved Region --- */
>  
>  /*
> diff --git a/include/hw/core/qdev-properties-system.h b/include/hw/core/qdev-properties-system.h
> index ec21732ce5..4708885164 100644
> --- a/include/hw/core/qdev-properties-system.h
> +++ b/include/hw/core/qdev-properties-system.h
> @@ -14,6 +14,7 @@ extern const PropertyInfo qdev_prop_multifd_compression;
>  extern const PropertyInfo qdev_prop_mig_mode;
>  extern const PropertyInfo qdev_prop_granule_mode;
>  extern const PropertyInfo qdev_prop_zero_page_detection;
> +extern const PropertyInfo qdev_prop_ssidsize_mode;
>  extern const PropertyInfo qdev_prop_losttickpolicy;
>  extern const PropertyInfo qdev_prop_blockdev_on_error;
>  extern const PropertyInfo qdev_prop_bios_chs_trans;
> @@ -61,6 +62,8 @@ extern const PropertyInfo qdev_prop_virtio_gpu_output_list;
>  #define DEFINE_PROP_ZERO_PAGE_DETECTION(_n, _s, _f, _d) \
>      DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_zero_page_detection, \
>                         ZeroPageDetection)
> +#define DEFINE_PROP_SSIDSIZE_MODE(_n, _s, _f, _d) \
> +    DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_ssidsize_mode, SsidSizeMode)
>  #define DEFINE_PROP_LOSTTICKPOLICY(_n, _s, _f, _d) \
>      DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_losttickpolicy, \
>                          LostTickPolicy)
> diff --git a/qapi/misc-arm.json b/qapi/misc-arm.json
> index f921d740f1..76ea0a09fa 100644
> --- a/qapi/misc-arm.json
> +++ b/qapi/misc-arm.json
> @@ -45,3 +45,19 @@
>  #                     { "version": 3, "emulated": false, "kernel": true } ] }
>  ##
>  { 'command': 'query-gic-capabilities', 'returns': ['GICCapability'] }
> +
> +##
> +# @SsidSizeMode:
> +#
> +# SMMUv3 SubstreamID size configuration mode.
> +#
> +# @auto: derive from host IOMMU capabilities
> +#
> +# Values 0-20: SSIDSIZE value in bits.  0 disables SubstreamID.
> +#
> +# Since: 11.0
> +##
> +{ 'enum': 'SsidSizeMode',
> +  'data': [ 'auto', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
> +            '10', '11', '12', '13', '14', '15', '16', '17', '18',
> +            '19', '20' ] } # order matters, see ssid_size_mode_auto()
> diff --git a/qapi/pragma.json b/qapi/pragma.json
> index 193bc39059..24aebbe8f5 100644
> --- a/qapi/pragma.json
> +++ b/qapi/pragma.json
> @@ -68,6 +68,7 @@
>          'S390CpuEntitlement',
>          'S390CpuPolarization',
>          'S390CpuState',
> +        'SsidSizeMode',
>          'String',
>          'StringWrapper',
>          'SysEmuTarget',

[PATCH v2 5/8] hw/arm/smmuv3-accel: Change SSIDSIZE property to SsidSizeMode

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Change accel SMMUv3 SSIDSIZE property from uint8_t to SsidSizeMode.
Setting 'auto' will use the default value, i.e. 0 in IDR1. A future
patch will implement resolution of 'auto' value to match the host SMMUv3
SSIDSIZE value.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/arm/smmuv3-accel.c   | 17 +++++++++++++++--
 hw/arm/smmuv3.c         | 16 ++++++----------
 include/hw/arm/smmuv3.h |  3 ++-
 3 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index 6f44fd3469..ab037df7ac 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -803,7 +803,7 @@ static uint64_t smmuv3_accel_get_viommu_flags(void *opaque)
     SMMUState *bs = opaque;
     SMMUv3State *s = ARM_SMMUV3(bs);
 
-    if (s->ssidsize) {
+    if (s->ssidsize > SSID_SIZE_MODE_0) {
         flags |= VIOMMU_FLAG_PASID_SUPPORTED;
     }
     return flags;
@@ -818,6 +818,16 @@ static const PCIIOMMUOps smmuv3_accel_ops = {
     .get_msi_direct_gpa = smmuv3_accel_get_msi_gpa,
 };
 
+static uint8_t ssidsize_mode_to_value(SsidSizeMode mode)
+{
+    /* SSID_SIZE_MODE_0 = 1, SSID_SIZE_MODE_1 = 2, etc. */
+    /* SSID_SIZE_MODE_AUTO = 0 */
+    if (mode == SSID_SIZE_MODE_AUTO) {
+        return 0;
+    }
+    return mode - 1;  /* Enum values are offset by 1 from actual values */
+}
+
 void smmuv3_accel_idr_override(SMMUv3State *s)
 {
     if (!s->accel) {
@@ -847,7 +857,10 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
      * By default QEMU SMMUv3 has no SubstreamID support. Update IDR1 if user
      * has enabled it.
      */
-    s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE, s->ssidsize);
+    if (s->ssidsize != SSID_SIZE_MODE_AUTO) {
+        s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE,
+                               ssidsize_mode_to_value(s->ssidsize));
+    }
 }
 
 /* Based on SMUUv3 GPBA.ABORT configuration, attach a corresponding HWPT */
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index acbd9d3ffe..8b0121c0ed 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -20,6 +20,7 @@
 #include "qemu/bitops.h"
 #include "hw/core/irq.h"
 #include "hw/core/sysbus.h"
+#include "hw/core/qdev-properties-system.h"
 #include "migration/blocker.h"
 #include "migration/vmstate.h"
 #include "hw/core/qdev-properties.h"
@@ -625,7 +626,7 @@ static int decode_ste(SMMUv3State *s, SMMUTransCfg *cfg,
     }
 
     /* Multiple context descriptors require SubstreamID support */
-    if (!s->ssidsize && STE_S1CDMAX(ste) != 0) {
+    if (s->ssidsize == SSID_SIZE_MODE_0 && STE_S1CDMAX(ste) != 0) {
         qemu_log_mask(LOG_UNIMP,
                 "SMMUv3: multiple S1 context descriptors require SubstreamID support. "
                 "Configure ssidsize > 0 (requires accel=on)\n");
@@ -1984,7 +1985,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
             error_setg(errp, "OAS must be 44 bits when accel=off");
             return false;
         }
-        if (s->ssidsize) {
+        if (s->ssidsize > SSID_SIZE_MODE_0) {
             error_setg(errp, "ssidsize can only be set if accel=on");
             return false;
         }
@@ -2002,11 +2003,6 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
         error_setg(errp, "OAS can only be set to 44 or 48 bits");
         return false;
     }
-    if (s->ssidsize > SMMU_SSID_MAX_BITS) {
-        error_setg(errp, "ssidsize must be in the range 0 to %d",
-                   SMMU_SSID_MAX_BITS);
-        return false;
-    }
 
     return true;
 }
@@ -2135,7 +2131,8 @@ static const Property smmuv3_properties[] = {
     DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril, ON_OFF_AUTO_ON),
     DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
     DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
-    DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
+    DEFINE_PROP_SSIDSIZE_MODE("ssidsize", SMMUv3State, ssidsize,
+                              SSID_SIZE_MODE_0),
 };
 
 static void smmuv3_instance_init(Object *obj)
@@ -2173,8 +2170,7 @@ static void smmuv3_class_init(ObjectClass *klass, const void *data)
         "Number of bits used to represent SubstreamIDs (SSIDs). "
         "A value of N allows SSIDs in the range [0 .. 2^N - 1]. "
         "Valid range is 0-20, where 0 disables SubstreamID support. "
-        "Defaults to 0. A value greater than 0 is required to enable "
-        "PASID support.");
+        "A value greater than 0 is required to enable PASID support.");
 }
 
 static int smmuv3_notify_flag_changed(IOMMUMemoryRegion *iommu,
diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
index c35e599bbc..ddf472493d 100644
--- a/include/hw/arm/smmuv3.h
+++ b/include/hw/arm/smmuv3.h
@@ -21,6 +21,7 @@
 
 #include "hw/arm/smmu-common.h"
 #include "qom/object.h"
+#include "qapi/qapi-types-misc-arm.h"
 
 #define TYPE_SMMUV3_IOMMU_MEMORY_REGION "smmuv3-iommu-memory-region"
 
@@ -72,7 +73,7 @@ struct SMMUv3State {
     OnOffAuto ril;
     OnOffAuto ats;
     uint8_t oas;
-    uint8_t ssidsize;
+    SsidSizeMode ssidsize;
 };
 
 typedef enum {
-- 
2.43.0

Re: [PATCH v2 5/8] hw/arm/smmuv3-accel: Change SSIDSIZE property to SsidSizeMode

[Eric Auger]

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Change accel SMMUv3 SSIDSIZE property from uint8_t to SsidSizeMode.
> Setting 'auto' will use the default value, i.e. 0 in IDR1. A future
> patch will implement resolution of 'auto' value to match the host SMMUv3
> SSIDSIZE value.

At the moment we need to reject auto setting as it is not supported

>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c   | 17 +++++++++++++++--
>  hw/arm/smmuv3.c         | 16 ++++++----------
>  include/hw/arm/smmuv3.h |  3 ++-
>  3 files changed, 23 insertions(+), 13 deletions(-)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index 6f44fd3469..ab037df7ac 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -803,7 +803,7 @@ static uint64_t smmuv3_accel_get_viommu_flags(void *opaque)
>      SMMUState *bs = opaque;
>      SMMUv3State *s = ARM_SMMUV3(bs);
>  
> -    if (s->ssidsize) {
> +    if (s->ssidsize > SSID_SIZE_MODE_0) {
>          flags |= VIOMMU_FLAG_PASID_SUPPORTED;
>      }
>      return flags;
> @@ -818,6 +818,16 @@ static const PCIIOMMUOps smmuv3_accel_ops = {
>      .get_msi_direct_gpa = smmuv3_accel_get_msi_gpa,
>  };
>  
> +static uint8_t ssidsize_mode_to_value(SsidSizeMode mode)
> +{
> +    /* SSID_SIZE_MODE_0 = 1, SSID_SIZE_MODE_1 = 2, etc. */
> +    /* SSID_SIZE_MODE_AUTO = 0 */
> +    if (mode == SSID_SIZE_MODE_AUTO) {
> +        return 0;
> +    }
> +    return mode - 1;  /* Enum values are offset by 1 from actual values */
> +}
> +
>  void smmuv3_accel_idr_override(SMMUv3State *s)
>  {
>      if (!s->accel) {
> @@ -847,7 +857,10 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>       * By default QEMU SMMUv3 has no SubstreamID support. Update IDR1 if user
>       * has enabled it.
>       */
> -    s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE, s->ssidsize);
> +    if (s->ssidsize != SSID_SIZE_MODE_AUTO) {
> +        s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE,
> +                               ssidsize_mode_to_value(s->ssidsize));
> +    }
>  }
>  
>  /* Based on SMUUv3 GPBA.ABORT configuration, attach a corresponding HWPT */
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index acbd9d3ffe..8b0121c0ed 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -20,6 +20,7 @@
>  #include "qemu/bitops.h"
>  #include "hw/core/irq.h"
>  #include "hw/core/sysbus.h"
> +#include "hw/core/qdev-properties-system.h"
>  #include "migration/blocker.h"
>  #include "migration/vmstate.h"
>  #include "hw/core/qdev-properties.h"
> @@ -625,7 +626,7 @@ static int decode_ste(SMMUv3State *s, SMMUTransCfg *cfg,
>      }
>  
>      /* Multiple context descriptors require SubstreamID support */
> -    if (!s->ssidsize && STE_S1CDMAX(ste) != 0) {
> +    if (s->ssidsize == SSID_SIZE_MODE_0 && STE_S1CDMAX(ste) != 0) {
>          qemu_log_mask(LOG_UNIMP,
>                  "SMMUv3: multiple S1 context descriptors require SubstreamID support. "
>                  "Configure ssidsize > 0 (requires accel=on)\n");
> @@ -1984,7 +1985,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>              error_setg(errp, "OAS must be 44 bits when accel=off");
>              return false;
>          }
> -        if (s->ssidsize) {
> +        if (s->ssidsize > SSID_SIZE_MODE_0) {
>              error_setg(errp, "ssidsize can only be set if accel=on");
>              return false;
>          }
> @@ -2002,11 +2003,6 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>          error_setg(errp, "OAS can only be set to 44 or 48 bits");
>          return false;
>      }
> -    if (s->ssidsize > SMMU_SSID_MAX_BITS) {
> -        error_setg(errp, "ssidsize must be in the range 0 to %d",
> -                   SMMU_SSID_MAX_BITS);
> -        return false;
> -    }
>  
>      return true;
>  }
> @@ -2135,7 +2131,8 @@ static const Property smmuv3_properties[] = {
>      DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril, ON_OFF_AUTO_ON),
>      DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
>      DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
> -    DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
> +    DEFINE_PROP_SSIDSIZE_MODE("ssidsize", SMMUv3State, ssidsize,
> +                              SSID_SIZE_MODE_0),
>  };
>  
>  static void smmuv3_instance_init(Object *obj)
> @@ -2173,8 +2170,7 @@ static void smmuv3_class_init(ObjectClass *klass, const void *data)
>          "Number of bits used to represent SubstreamIDs (SSIDs). "
>          "A value of N allows SSIDs in the range [0 .. 2^N - 1]. "
>          "Valid range is 0-20, where 0 disables SubstreamID support. "
> -        "Defaults to 0. A value greater than 0 is required to enable "
> -        "PASID support.");
> +        "A value greater than 0 is required to enable PASID support.");
Why removing "Defaults to 0"?
>  }
>  
>  static int smmuv3_notify_flag_changed(IOMMUMemoryRegion *iommu,
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index c35e599bbc..ddf472493d 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -21,6 +21,7 @@
>  
>  #include "hw/arm/smmu-common.h"
>  #include "qom/object.h"
> +#include "qapi/qapi-types-misc-arm.h"
>  
>  #define TYPE_SMMUV3_IOMMU_MEMORY_REGION "smmuv3-iommu-memory-region"
>  
> @@ -72,7 +73,7 @@ struct SMMUv3State {
>      OnOffAuto ril;
>      OnOffAuto ats;
>      uint8_t oas;
> -    uint8_t ssidsize;
> +    SsidSizeMode ssidsize;
>  };
>  
>  typedef enum {
Thanks

Eric

Re: [PATCH v2 5/8] hw/arm/smmuv3-accel: Change SSIDSIZE property to SsidSizeMode

[Nathan Chen]

On 3/16/2026 12:50 AM, Eric Auger wrote:
> On 3/12/26 10:03 PM, Nathan Chen wrote:
>> From: Nathan Chen<nathanc@nvidia.com>
>>
>> Change accel SMMUv3 SSIDSIZE property from uint8_t to SsidSizeMode.
>> Setting 'auto' will use the default value, i.e. 0 in IDR1. A future
>> patch will implement resolution of 'auto' value to match the host SMMUv3
>> SSIDSIZE value.
> At the moment we need to reject auto setting as it is not supported
> 
I will enforce rejecting auto setting for this and the other properties 
in the next refresh.
>> Signed-off-by: Nathan Chen<nathanc@nvidia.com>
>> ---
>>   hw/arm/smmuv3-accel.c   | 17 +++++++++++++++--
>>   hw/arm/smmuv3.c         | 16 ++++++----------
>>   include/hw/arm/smmuv3.h |  3 ++-
>>   3 files changed, 23 insertions(+), 13 deletions(-)
>>
>> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
>> index 6f44fd3469..ab037df7ac 100644
>> --- a/hw/arm/smmuv3-accel.c
>> +++ b/hw/arm/smmuv3-accel.c
>> @@ -803,7 +803,7 @@ static uint64_t smmuv3_accel_get_viommu_flags(void *opaque)
>>       SMMUState *bs = opaque;
>>       SMMUv3State *s = ARM_SMMUV3(bs);
>>   
>> -    if (s->ssidsize) {
>> +    if (s->ssidsize > SSID_SIZE_MODE_0) {
>>           flags |= VIOMMU_FLAG_PASID_SUPPORTED;
>>       }
>>       return flags;
>> @@ -818,6 +818,16 @@ static const PCIIOMMUOps smmuv3_accel_ops = {
>>       .get_msi_direct_gpa = smmuv3_accel_get_msi_gpa,
>>   };
>>   
>> +static uint8_t ssidsize_mode_to_value(SsidSizeMode mode)
>> +{
>> +    /* SSID_SIZE_MODE_0 = 1, SSID_SIZE_MODE_1 = 2, etc. */
>> +    /* SSID_SIZE_MODE_AUTO = 0 */
>> +    if (mode == SSID_SIZE_MODE_AUTO) {
>> +        return 0;
>> +    }
>> +    return mode - 1;  /* Enum values are offset by 1 from actual values */
>> +}
>> +
>>   void smmuv3_accel_idr_override(SMMUv3State *s)
>>   {
>>       if (!s->accel) {
>> @@ -847,7 +857,10 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>>        * By default QEMU SMMUv3 has no SubstreamID support. Update IDR1 if user
>>        * has enabled it.
>>        */
>> -    s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE, s->ssidsize);
>> +    if (s->ssidsize != SSID_SIZE_MODE_AUTO) {
>> +        s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE,
>> +                               ssidsize_mode_to_value(s->ssidsize));
>> +    }
>>   }
>>   
>>   /* Based on SMUUv3 GPBA.ABORT configuration, attach a corresponding HWPT */
>> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
>> index acbd9d3ffe..8b0121c0ed 100644
>> --- a/hw/arm/smmuv3.c
>> +++ b/hw/arm/smmuv3.c
>> @@ -20,6 +20,7 @@
>>   #include "qemu/bitops.h"
>>   #include "hw/core/irq.h"
>>   #include "hw/core/sysbus.h"
>> +#include "hw/core/qdev-properties-system.h"
>>   #include "migration/blocker.h"
>>   #include "migration/vmstate.h"
>>   #include "hw/core/qdev-properties.h"
>> @@ -625,7 +626,7 @@ static int decode_ste(SMMUv3State *s, SMMUTransCfg *cfg,
>>       }
>>   
>>       /* Multiple context descriptors require SubstreamID support */
>> -    if (!s->ssidsize && STE_S1CDMAX(ste) != 0) {
>> +    if (s->ssidsize == SSID_SIZE_MODE_0 && STE_S1CDMAX(ste) != 0) {
>>           qemu_log_mask(LOG_UNIMP,
>>                   "SMMUv3: multiple S1 context descriptors require SubstreamID support. "
>>                   "Configure ssidsize > 0 (requires accel=on)\n");
>> @@ -1984,7 +1985,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>>               error_setg(errp, "OAS must be 44 bits when accel=off");
>>               return false;
>>           }
>> -        if (s->ssidsize) {
>> +        if (s->ssidsize > SSID_SIZE_MODE_0) {
>>               error_setg(errp, "ssidsize can only be set if accel=on");
>>               return false;
>>           }
>> @@ -2002,11 +2003,6 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>>           error_setg(errp, "OAS can only be set to 44 or 48 bits");
>>           return false;
>>       }
>> -    if (s->ssidsize > SMMU_SSID_MAX_BITS) {
>> -        error_setg(errp, "ssidsize must be in the range 0 to %d",
>> -                   SMMU_SSID_MAX_BITS);
>> -        return false;
>> -    }
>>   
>>       return true;
>>   }
>> @@ -2135,7 +2131,8 @@ static const Property smmuv3_properties[] = {
>>       DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril, ON_OFF_AUTO_ON),
>>       DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
>>       DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
>> -    DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
>> +    DEFINE_PROP_SSIDSIZE_MODE("ssidsize", SMMUv3State, ssidsize,
>> +                              SSID_SIZE_MODE_0),
>>   };
>>   
>>   static void smmuv3_instance_init(Object *obj)
>> @@ -2173,8 +2170,7 @@ static void smmuv3_class_init(ObjectClass *klass, const void *data)
>>           "Number of bits used to represent SubstreamIDs (SSIDs). "
>>           "A value of N allows SSIDs in the range [0 .. 2^N - 1]. "
>>           "Valid range is 0-20, where 0 disables SubstreamID support. "
>> -        "Defaults to 0. A value greater than 0 is required to enable "
>> -        "PASID support.");
>> +        "A value greater than 0 is required to enable PASID support.");
> Why removing "Defaults to 0"?

This was left over from the v1 RFC. I will fix this in the next refresh.

Thanks,
Nathan

RE: [PATCH v2 5/8] hw/arm/smmuv3-accel: Change SSIDSIZE property to SsidSizeMode

[Shameer Kolothum Thodi]

> -----Original Message-----
> From: Nathan Chen <nathanc@nvidia.com>
> Sent: 12 March 2026 21:03
> To: qemu-devel@nongnu.org; qemu-arm@nongnu.org
> Cc: Eric Auger <eric.auger@redhat.com>; Peter Maydell
> <peter.maydell@linaro.org>; Michael S . Tsirkin <mst@redhat.com>; Igor
> Mammedov <imammedo@redhat.com>; Ani Sinha <anisinha@redhat.com>;
> Shannon Zhao <shannon.zhaosl@gmail.com>; Paolo Bonzini
> <pbonzini@redhat.com>; Daniel P . Berrangé <berrange@redhat.com>;
> Eduardo Habkost <eduardo@habkost.net>; Eric Blake <eblake@redhat.com>;
> Markus Armbruster <armbru@redhat.com>; Shameer Kolothum Thodi
> <skolothumtho@nvidia.com>; Nicolin Chen <nicolinc@nvidia.com>; Matt
> Ochs <mochs@nvidia.com>; Nathan Chen <nathanc@nvidia.com>
> Subject: [PATCH v2 5/8] hw/arm/smmuv3-accel: Change SSIDSIZE property to
> SsidSizeMode
> 
> From: Nathan Chen <nathanc@nvidia.com>
> 
> Change accel SMMUv3 SSIDSIZE property from uint8_t to SsidSizeMode.
> Setting 'auto' will use the default value, i.e. 0 in IDR1. A future
> patch will implement resolution of 'auto' value to match the host SMMUv3
> SSIDSIZE value.
> 
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c   | 17 +++++++++++++++--
>  hw/arm/smmuv3.c         | 16 ++++++----------
>  include/hw/arm/smmuv3.h |  3 ++-
>  3 files changed, 23 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index 6f44fd3469..ab037df7ac 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -803,7 +803,7 @@ static uint64_t
> smmuv3_accel_get_viommu_flags(void *opaque)
>      SMMUState *bs = opaque;
>      SMMUv3State *s = ARM_SMMUV3(bs);
> 
> -    if (s->ssidsize) {
> +    if (s->ssidsize > SSID_SIZE_MODE_0) {
>          flags |= VIOMMU_FLAG_PASID_SUPPORTED;
>      }
>      return flags;
> @@ -818,6 +818,16 @@ static const PCIIOMMUOps smmuv3_accel_ops = {
>      .get_msi_direct_gpa = smmuv3_accel_get_msi_gpa,
>  };
> 
> +static uint8_t ssidsize_mode_to_value(SsidSizeMode mode)
> +{
> +    /* SSID_SIZE_MODE_0 = 1, SSID_SIZE_MODE_1 = 2, etc. */
> +    /* SSID_SIZE_MODE_AUTO = 0 */
> +    if (mode == SSID_SIZE_MODE_AUTO) {
> +        return 0;
> +    }
> +    return mode - 1;  /* Enum values are offset by 1 from actual values */
> +}

Maybe better to consolidate these comments and move them to a
function level block comment above.

Thanks,
Shameer

> +
>  void smmuv3_accel_idr_override(SMMUv3State *s)
>  {
>      if (!s->accel) {
> @@ -847,7 +857,10 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>       * By default QEMU SMMUv3 has no SubstreamID support. Update IDR1 if
> user
>       * has enabled it.
>       */
> -    s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE, s->ssidsize);
> +    if (s->ssidsize != SSID_SIZE_MODE_AUTO) {
> +        s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE,
> +                               ssidsize_mode_to_value(s->ssidsize));
> +    }
>  }
> 
>  /* Based on SMUUv3 GPBA.ABORT configuration, attach a corresponding
> HWPT */
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index acbd9d3ffe..8b0121c0ed 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -20,6 +20,7 @@
>  #include "qemu/bitops.h"
>  #include "hw/core/irq.h"
>  #include "hw/core/sysbus.h"
> +#include "hw/core/qdev-properties-system.h"
>  #include "migration/blocker.h"
>  #include "migration/vmstate.h"
>  #include "hw/core/qdev-properties.h"
> @@ -625,7 +626,7 @@ static int decode_ste(SMMUv3State *s,
> SMMUTransCfg *cfg,
>      }
> 
>      /* Multiple context descriptors require SubstreamID support */
> -    if (!s->ssidsize && STE_S1CDMAX(ste) != 0) {
> +    if (s->ssidsize == SSID_SIZE_MODE_0 && STE_S1CDMAX(ste) != 0) {
>          qemu_log_mask(LOG_UNIMP,
>                  "SMMUv3: multiple S1 context descriptors require SubstreamID
> support. "
>                  "Configure ssidsize > 0 (requires accel=on)\n");
> @@ -1984,7 +1985,7 @@ static bool
> smmu_validate_property(SMMUv3State *s, Error **errp)
>              error_setg(errp, "OAS must be 44 bits when accel=off");
>              return false;
>          }
> -        if (s->ssidsize) {
> +        if (s->ssidsize > SSID_SIZE_MODE_0) {
>              error_setg(errp, "ssidsize can only be set if accel=on");
>              return false;
>          }
> @@ -2002,11 +2003,6 @@ static bool
> smmu_validate_property(SMMUv3State *s, Error **errp)
>          error_setg(errp, "OAS can only be set to 44 or 48 bits");
>          return false;
>      }
> -    if (s->ssidsize > SMMU_SSID_MAX_BITS) {
> -        error_setg(errp, "ssidsize must be in the range 0 to %d",
> -                   SMMU_SSID_MAX_BITS);
> -        return false;
> -    }
> 
>      return true;
>  }
> @@ -2135,7 +2131,8 @@ static const Property smmuv3_properties[] = {
>      DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril,
> ON_OFF_AUTO_ON),
>      DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats,
> ON_OFF_AUTO_OFF),
>      DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
> -    DEFINE_PROP_UINT8("ssidsize", SMMUv3State, ssidsize, 0),
> +    DEFINE_PROP_SSIDSIZE_MODE("ssidsize", SMMUv3State, ssidsize,
> +                              SSID_SIZE_MODE_0),
>  };
> 
>  static void smmuv3_instance_init(Object *obj)
> @@ -2173,8 +2170,7 @@ static void smmuv3_class_init(ObjectClass *klass,
> const void *data)
>          "Number of bits used to represent SubstreamIDs (SSIDs). "
>          "A value of N allows SSIDs in the range [0 .. 2^N - 1]. "
>          "Valid range is 0-20, where 0 disables SubstreamID support. "
> -        "Defaults to 0. A value greater than 0 is required to enable "
> -        "PASID support.");
> +        "A value greater than 0 is required to enable PASID support.");
>  }
> 
>  static int smmuv3_notify_flag_changed(IOMMUMemoryRegion *iommu,
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index c35e599bbc..ddf472493d 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -21,6 +21,7 @@
> 
>  #include "hw/arm/smmu-common.h"
>  #include "qom/object.h"
> +#include "qapi/qapi-types-misc-arm.h"
> 
>  #define TYPE_SMMUV3_IOMMU_MEMORY_REGION "smmuv3-iommu-
> memory-region"
> 
> @@ -72,7 +73,7 @@ struct SMMUv3State {
>      OnOffAuto ril;
>      OnOffAuto ats;
>      uint8_t oas;
> -    uint8_t ssidsize;
> +    SsidSizeMode ssidsize;
>  };
> 
>  typedef enum {
> --
> 2.43.0

Re: [PATCH v2 5/8] hw/arm/smmuv3-accel: Change SSIDSIZE property to SsidSizeMode

[Nathan Chen]

On 3/16/2026 1:56 AM, Shameer Kolothum Thodi wrote:
> 
>> -----Original Message-----
>> From: Nathan Chen<nathanc@nvidia.com>
>> Sent: 12 March 2026 21:03
>> To:qemu-devel@nongnu.org;qemu-arm@nongnu.org
>> Cc: Eric Auger<eric.auger@redhat.com>; Peter Maydell
>> <peter.maydell@linaro.org>; Michael S . Tsirkin<mst@redhat.com>; Igor
>> Mammedov<imammedo@redhat.com>; Ani Sinha<anisinha@redhat.com>;
>> Shannon Zhao<shannon.zhaosl@gmail.com>; Paolo Bonzini
>> <pbonzini@redhat.com>; Daniel P . Berrangé<berrange@redhat.com>;
>> Eduardo Habkost<eduardo@habkost.net>; Eric Blake<eblake@redhat.com>;
>> Markus Armbruster<armbru@redhat.com>; Shameer Kolothum Thodi
>> <skolothumtho@nvidia.com>; Nicolin Chen<nicolinc@nvidia.com>; Matt
>> Ochs<mochs@nvidia.com>; Nathan Chen<nathanc@nvidia.com>
>> Subject: [PATCH v2 5/8] hw/arm/smmuv3-accel: Change SSIDSIZE property to
>> SsidSizeMode
>>
>> From: Nathan Chen<nathanc@nvidia.com>
>>
>> Change accel SMMUv3 SSIDSIZE property from uint8_t to SsidSizeMode.
>> Setting 'auto' will use the default value, i.e. 0 in IDR1. A future
>> patch will implement resolution of 'auto' value to match the host SMMUv3
>> SSIDSIZE value.
>>
>> Signed-off-by: Nathan Chen<nathanc@nvidia.com>
>> ---
>>   hw/arm/smmuv3-accel.c   | 17 +++++++++++++++--
>>   hw/arm/smmuv3.c         | 16 ++++++----------
>>   include/hw/arm/smmuv3.h |  3 ++-
>>   3 files changed, 23 insertions(+), 13 deletions(-)
>>
>> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
>> index 6f44fd3469..ab037df7ac 100644
>> --- a/hw/arm/smmuv3-accel.c
>> +++ b/hw/arm/smmuv3-accel.c
>> @@ -803,7 +803,7 @@ static uint64_t
>> smmuv3_accel_get_viommu_flags(void *opaque)
>>       SMMUState *bs = opaque;
>>       SMMUv3State *s = ARM_SMMUV3(bs);
>>
>> -    if (s->ssidsize) {
>> +    if (s->ssidsize > SSID_SIZE_MODE_0) {
>>           flags |= VIOMMU_FLAG_PASID_SUPPORTED;
>>       }
>>       return flags;
>> @@ -818,6 +818,16 @@ static const PCIIOMMUOps smmuv3_accel_ops = {
>>       .get_msi_direct_gpa = smmuv3_accel_get_msi_gpa,
>>   };
>>
>> +static uint8_t ssidsize_mode_to_value(SsidSizeMode mode)
>> +{
>> +    /* SSID_SIZE_MODE_0 = 1, SSID_SIZE_MODE_1 = 2, etc. */
>> +    /* SSID_SIZE_MODE_AUTO = 0 */
>> +    if (mode == SSID_SIZE_MODE_AUTO) {
>> +        return 0;
>> +    }
>> +    return mode - 1;  /* Enum values are offset by 1 from actual values */
>> +}
> Maybe better to consolidate these comments and move them to a
> function level block comment above.

Yes, I will move it above and include more details about the function 
implementation in the block comment.

Thanks,
Nathan

[PATCH v2 6/8] qdev: Add an OasMode property

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Introduce a new enum type property allowing to set an Output Address
Size. Values are auto, 32, 36, 40, 42, 44, 48, 52, and 56, where a
value of N specifies an N-bit OAS.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/core/qdev-properties-system.c         | 13 +++++++++++
 include/hw/core/qdev-properties-system.h |  3 +++
 qapi/misc-arm.json                       | 28 ++++++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 4aca1d4326..a805ee2e1f 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -737,6 +737,19 @@ const PropertyInfo qdev_prop_ssidsize_mode = {
     .set_default_value = qdev_propinfo_set_default_value_enum,
 };
 
+/* --- OasMode --- */
+
+QEMU_BUILD_BUG_ON(sizeof(OasMode) != sizeof(int));
+
+const PropertyInfo qdev_prop_oas_mode = {
+    .type = "OasMode",
+    .description = "oas mode: auto, 32, 36, 40, 42, 44, 48, 52, 56",
+    .enum_table = &OasMode_lookup,
+    .get = qdev_propinfo_get_enum,
+    .set = qdev_propinfo_set_enum,
+    .set_default_value = qdev_propinfo_set_default_value_enum,
+};
+
 /* --- Reserved Region --- */
 
 /*
diff --git a/include/hw/core/qdev-properties-system.h b/include/hw/core/qdev-properties-system.h
index 4708885164..2cbea16d61 100644
--- a/include/hw/core/qdev-properties-system.h
+++ b/include/hw/core/qdev-properties-system.h
@@ -15,6 +15,7 @@ extern const PropertyInfo qdev_prop_mig_mode;
 extern const PropertyInfo qdev_prop_granule_mode;
 extern const PropertyInfo qdev_prop_zero_page_detection;
 extern const PropertyInfo qdev_prop_ssidsize_mode;
+extern const PropertyInfo qdev_prop_oas_mode;
 extern const PropertyInfo qdev_prop_losttickpolicy;
 extern const PropertyInfo qdev_prop_blockdev_on_error;
 extern const PropertyInfo qdev_prop_bios_chs_trans;
@@ -64,6 +65,8 @@ extern const PropertyInfo qdev_prop_virtio_gpu_output_list;
                        ZeroPageDetection)
 #define DEFINE_PROP_SSIDSIZE_MODE(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_ssidsize_mode, SsidSizeMode)
+#define DEFINE_PROP_OAS_MODE(_n, _s, _f, _d) \
+    DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_oas_mode, OasMode)
 #define DEFINE_PROP_LOSTTICKPOLICY(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_losttickpolicy, \
                         LostTickPolicy)
diff --git a/qapi/misc-arm.json b/qapi/misc-arm.json
index 76ea0a09fa..5dbb4add91 100644
--- a/qapi/misc-arm.json
+++ b/qapi/misc-arm.json
@@ -61,3 +61,31 @@
   'data': [ 'auto', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
             '10', '11', '12', '13', '14', '15', '16', '17', '18',
             '19', '20' ] } # order matters, see ssid_size_mode_auto()
+
+##
+# @OasMode:
+#
+# SMMUv3 Output Address Size configuration mode.
+#
+# @auto: derive from host IOMMU capabilities
+#
+# @32: 32-bit output address size
+#
+# @36: 36-bit output address size
+#
+# @40: 40-bit output address size
+#
+# @42: 42-bit output address size
+#
+# @44: 44-bit output address size
+#
+# @48: 48-bit output address size
+#
+# @52: 52-bit output address size
+#
+# @56: 56-bit output address size
+#
+# Since: 11.0
+##
+{ 'enum': 'OasMode',
+  'data': [ 'auto', '32', '36', '40', '42', '44', '48', '52', '56' ] }
-- 
2.43.0

Re: [PATCH v2 6/8] qdev: Add an OasMode property

[Eric Auger]

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Introduce a new enum type property allowing to set an Output Address
> Size. Values are auto, 32, 36, 40, 42, 44, 48, 52, and 56, where a
> value of N specifies an N-bit OAS.
>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/core/qdev-properties-system.c         | 13 +++++++++++
>  include/hw/core/qdev-properties-system.h |  3 +++
>  qapi/misc-arm.json                       | 28 ++++++++++++++++++++++++
>  3 files changed, 44 insertions(+)
>
> diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
> index 4aca1d4326..a805ee2e1f 100644
> --- a/hw/core/qdev-properties-system.c
> +++ b/hw/core/qdev-properties-system.c
> @@ -737,6 +737,19 @@ const PropertyInfo qdev_prop_ssidsize_mode = {
>      .set_default_value = qdev_propinfo_set_default_value_enum,
>  };
>  
> +/* --- OasMode --- */
> +
> +QEMU_BUILD_BUG_ON(sizeof(OasMode) != sizeof(int));
> +
> +const PropertyInfo qdev_prop_oas_mode = {
> +    .type = "OasMode",
> +    .description = "oas mode: auto, 32, 36, 40, 42, 44, 48, 52, 56",
> +    .enum_table = &OasMode_lookup,
> +    .get = qdev_propinfo_get_enum,
> +    .set = qdev_propinfo_set_enum,
> +    .set_default_value = qdev_propinfo_set_default_value_enum,
> +};
> +
>  /* --- Reserved Region --- */
>  
>  /*
> diff --git a/include/hw/core/qdev-properties-system.h b/include/hw/core/qdev-properties-system.h
> index 4708885164..2cbea16d61 100644
> --- a/include/hw/core/qdev-properties-system.h
> +++ b/include/hw/core/qdev-properties-system.h
> @@ -15,6 +15,7 @@ extern const PropertyInfo qdev_prop_mig_mode;
>  extern const PropertyInfo qdev_prop_granule_mode;
>  extern const PropertyInfo qdev_prop_zero_page_detection;
>  extern const PropertyInfo qdev_prop_ssidsize_mode;
> +extern const PropertyInfo qdev_prop_oas_mode;
>  extern const PropertyInfo qdev_prop_losttickpolicy;
>  extern const PropertyInfo qdev_prop_blockdev_on_error;
>  extern const PropertyInfo qdev_prop_bios_chs_trans;
> @@ -64,6 +65,8 @@ extern const PropertyInfo qdev_prop_virtio_gpu_output_list;
>                         ZeroPageDetection)
>  #define DEFINE_PROP_SSIDSIZE_MODE(_n, _s, _f, _d) \
>      DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_ssidsize_mode, SsidSizeMode)
> +#define DEFINE_PROP_OAS_MODE(_n, _s, _f, _d) \
> +    DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_oas_mode, OasMode)
>  #define DEFINE_PROP_LOSTTICKPOLICY(_n, _s, _f, _d) \
>      DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_losttickpolicy, \
>                          LostTickPolicy)
> diff --git a/qapi/misc-arm.json b/qapi/misc-arm.json
> index 76ea0a09fa..5dbb4add91 100644
> --- a/qapi/misc-arm.json
> +++ b/qapi/misc-arm.json
> @@ -61,3 +61,31 @@
>    'data': [ 'auto', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
>              '10', '11', '12', '13', '14', '15', '16', '17', '18',
>              '19', '20' ] } # order matters, see ssid_size_mode_auto()
> +
> +##
> +# @OasMode:
> +#
> +# SMMUv3 Output Address Size configuration mode.
> +#
> +# @auto: derive from host IOMMU capabilities
> +#
> +# @32: 32-bit output address size
> +#
> +# @36: 36-bit output address size
> +#
> +# @40: 40-bit output address size
> +#
> +# @42: 42-bit output address size
> +#
> +# @44: 44-bit output address size
> +#
> +# @48: 48-bit output address size
> +#
> +# @52: 52-bit output address size
> +#
> +# @56: 56-bit output address size
> +#
> +# Since: 11.0
> +##
> +{ 'enum': 'OasMode',
> +  'data': [ 'auto', '32', '36', '40', '42', '44', '48', '52', '56' ] }
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric

[PATCH v2 7/8] hw/arm/smmuv3-accel: Change OAS property to OasMode

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Change accel SMMUv3 OAS property from uint8_t to OasMode. Setting
'auto' will use the default value of 44 set in smmuv3_init_id_regs().
A future patch will implement resolution of 'auto' value to match
the host SMMUv3 OAS value.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/arm/smmuv3-accel.c   | 2 +-
 hw/arm/smmuv3.c         | 9 +++++----
 include/hw/arm/smmuv3.h | 2 +-
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index ab037df7ac..5073f74b8b 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -849,7 +849,7 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
     }
 
     /* Advertise 48-bit OAS in IDR5 when requested (default is 44 bits). */
-    if (s->oas == SMMU_OAS_48BIT) {
+    if (s->oas == OAS_MODE_48) {
         s->idr[5] = FIELD_DP32(s->idr[5], IDR5, OAS, SMMU_IDR5_OAS_48);
     }
 
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 8b0121c0ed..9faa9c8dfb 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -1981,7 +1981,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
             error_setg(errp, "ats can only be enabled if accel=on");
             return false;
         }
-        if (s->oas != SMMU_OAS_44BIT) {
+        if (s->oas > OAS_MODE_44) {
             error_setg(errp, "OAS must be 44 bits when accel=off");
             return false;
         }
@@ -1999,8 +1999,9 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
         return false;
     }
 
-    if (s->oas != SMMU_OAS_44BIT && s->oas != SMMU_OAS_48BIT) {
-        error_setg(errp, "OAS can only be set to 44 or 48 bits");
+    if (s->oas != OAS_MODE_AUTO && s->oas != OAS_MODE_44 &&
+        s->oas != OAS_MODE_48) {
+        error_setg(errp, "OAS can only be set to auto, 44 bits, or 48 bits");
         return false;
     }
 
@@ -2130,7 +2131,7 @@ static const Property smmuv3_properties[] = {
     /* RIL can be turned off for accel cases */
     DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril, ON_OFF_AUTO_ON),
     DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
-    DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
+    DEFINE_PROP_OAS_MODE("oas", SMMUv3State, oas, OAS_MODE_44),
     DEFINE_PROP_SSIDSIZE_MODE("ssidsize", SMMUv3State, ssidsize,
                               SSID_SIZE_MODE_0),
 };
diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
index ddf472493d..82f18eb090 100644
--- a/include/hw/arm/smmuv3.h
+++ b/include/hw/arm/smmuv3.h
@@ -72,7 +72,7 @@ struct SMMUv3State {
     Error *migration_blocker;
     OnOffAuto ril;
     OnOffAuto ats;
-    uint8_t oas;
+    OasMode oas;
     SsidSizeMode ssidsize;
 };
 
-- 
2.43.0

Re: [PATCH v2 7/8] hw/arm/smmuv3-accel: Change OAS property to OasMode

[Eric Auger]

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Change accel SMMUv3 OAS property from uint8_t to OasMode. Setting
> 'auto' will use the default value of 44 set in smmuv3_init_id_regs().
> A future patch will implement resolution of 'auto' value to match
> the host SMMUv3 OAS value.
Same I think we don't want auto mode to be selectable at the moment.
Because then you will change the semantic of the auto mode, returning
the host value and not 44 anymore.

Eric
>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c   | 2 +-
>  hw/arm/smmuv3.c         | 9 +++++----
>  include/hw/arm/smmuv3.h | 2 +-
>  3 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index ab037df7ac..5073f74b8b 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -849,7 +849,7 @@ void smmuv3_accel_idr_override(SMMUv3State *s)
>      }
>  
>      /* Advertise 48-bit OAS in IDR5 when requested (default is 44 bits). */
> -    if (s->oas == SMMU_OAS_48BIT) {
> +    if (s->oas == OAS_MODE_48) {
>          s->idr[5] = FIELD_DP32(s->idr[5], IDR5, OAS, SMMU_IDR5_OAS_48);
>      }
>  
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 8b0121c0ed..9faa9c8dfb 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -1981,7 +1981,7 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>              error_setg(errp, "ats can only be enabled if accel=on");
>              return false;
>          }
> -        if (s->oas != SMMU_OAS_44BIT) {
> +        if (s->oas > OAS_MODE_44) {
>              error_setg(errp, "OAS must be 44 bits when accel=off");
>              return false;
>          }
> @@ -1999,8 +1999,9 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)
>          return false;
>      }
>  
> -    if (s->oas != SMMU_OAS_44BIT && s->oas != SMMU_OAS_48BIT) {
> -        error_setg(errp, "OAS can only be set to 44 or 48 bits");
> +    if (s->oas != OAS_MODE_AUTO && s->oas != OAS_MODE_44 &&
> +        s->oas != OAS_MODE_48) {
> +        error_setg(errp, "OAS can only be set to auto, 44 bits, or 48 bits");
>          return false;
>      }
>  
> @@ -2130,7 +2131,7 @@ static const Property smmuv3_properties[] = {
>      /* RIL can be turned off for accel cases */
>      DEFINE_PROP_ON_OFF_AUTO("ril", SMMUv3State, ril, ON_OFF_AUTO_ON),
>      DEFINE_PROP_ON_OFF_AUTO("ats", SMMUv3State, ats, ON_OFF_AUTO_OFF),
> -    DEFINE_PROP_UINT8("oas", SMMUv3State, oas, 44),
> +    DEFINE_PROP_OAS_MODE("oas", SMMUv3State, oas, OAS_MODE_44),
>      DEFINE_PROP_SSIDSIZE_MODE("ssidsize", SMMUv3State, ssidsize,
>                                SSID_SIZE_MODE_0),
>  };
> diff --git a/include/hw/arm/smmuv3.h b/include/hw/arm/smmuv3.h
> index ddf472493d..82f18eb090 100644
> --- a/include/hw/arm/smmuv3.h
> +++ b/include/hw/arm/smmuv3.h
> @@ -72,7 +72,7 @@ struct SMMUv3State {
>      Error *migration_blocker;
>      OnOffAuto ril;
>      OnOffAuto ats;
> -    uint8_t oas;
> +    OasMode oas;
>      SsidSizeMode ssidsize;
>  };
>  

[PATCH v2 8/8] qemu-options.hx: Document arm-smmuv3 device's accel properties

[Nathan Chen]

From: Nathan Chen <nathanc@nvidia.com>

Document arm-smmuv3 properties for setting HW-acceleration,
Range Invalidation, and Address Translation Services support, as
well as setting Output Address size and Substream ID size.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 qemu-options.hx | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/qemu-options.hx b/qemu-options.hx
index 890c4f1d23..836de4532c 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1274,13 +1274,40 @@ SRST
     ``aw-bits=val`` (val between 32 and 64, default depends on machine)
         This decides the address width of the IOVA address space.
 
-``-device arm-smmuv3,primary-bus=id``
+``-device arm-smmuv3,primary-bus=id[,option=...]``
     This is only supported by ``-machine virt`` (ARM).
 
     ``primary-bus=id``
         Accepts either the default root complex (pcie.0) or a
         pxb-pcie based root complex.
 
+    ``accel=on|off`` (default: off)
+        Enables guest to try to leverage host SMMUv3 features for acceleration.
+        By default, enabling accel configures the host SMMUv3 in nested mode to
+        support vfio-pci pass-through.
+
+    ``ril=on|off`` (default: on)
+        Support for Range Invalidation, which allows the SMMUv3 driver to
+        invalidate TLB entries for a range of IOVAs at once instead of issuing
+        separate commands to invalidate each page. Must match with host SMMUv3
+        Range Invalidation support.
+
+    ``ats=on|off`` (default: off)
+        Support for Address Translation Services, which enables PCIe devices to
+        cache address translations in their local TLB and reduce latency. Host
+        SMMUv3 must support ATS in order to enable this feature for the vIOMMU.
+
+    ``oas=val`` (supported values are 44 and 48. default: 44)
+        Sets the Output Address Size in bits. The value set here must be less
+        than or equal to the host SMMUv3's supported OAS, so that the
+        intermediate physical addresses (IPA) consumed by host SMMU for stage-2
+        translation do not exceed the host's max supported IPA size.
+
+    ``ssidsize=val`` (val between 0 and 20. default: 0)
+        Sets the Substream ID size in bits. When set to a non-zero value,
+        PASID capability is advertised to the vIOMMU and accelerated use cases
+        such as Shared Virtual Addressing (SVA) are supported.
+
 ``-device amd-iommu[,option=...]``
     Enables emulation of an AMD-Vi I/O Memory Management Unit (IOMMU).
     Only available with ``-machine q35``, it supports the following options:
-- 
2.43.0

Re: [PATCH v2 8/8] qemu-options.hx: Document arm-smmuv3 device's accel properties

[Eric Auger]

On 3/12/26 10:03 PM, Nathan Chen wrote:
> From: Nathan Chen <nathanc@nvidia.com>
>
> Document arm-smmuv3 properties for setting HW-acceleration,
> Range Invalidation, and Address Translation Services support, as
> well as setting Output Address size and Substream ID size.
>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  qemu-options.hx | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 890c4f1d23..836de4532c 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1274,13 +1274,40 @@ SRST
>      ``aw-bits=val`` (val between 32 and 64, default depends on machine)
>          This decides the address width of the IOVA address space.
>  
> -``-device arm-smmuv3,primary-bus=id``
> +``-device arm-smmuv3,primary-bus=id[,option=...]``
>      This is only supported by ``-machine virt`` (ARM).
>  
>      ``primary-bus=id``
>          Accepts either the default root complex (pcie.0) or a
>          pxb-pcie based root complex.
>  
> +    ``accel=on|off`` (default: off)
> +        Enables guest to try to leverage host SMMUv3 features for acceleration.
Enables guest to leverage
> +        By default, enabling accel configures the host SMMUv3 in nested mode to
I would remove "By default, "
> +        support vfio-pci pass-through.
passthrough
> +
> +    ``ril=on|off`` (default: on)
> +        Support for Range Invalidation, which allows the SMMUv3 driver to
> +        invalidate TLB entries for a range of IOVAs at once instead of issuing
> +        separate commands to invalidate each page. Must match with host SMMUv3
> +        Range Invalidation support.
> +
> +    ``ats=on|off`` (default: off)
> +        Support for Address Translation Services, which enables PCIe devices to
> +        cache address translations in their local TLB and reduce latency. Host
> +        SMMUv3 must support ATS in order to enable this feature for the vIOMMU.
> +
> +    ``oas=val`` (supported values are 44 and 48. default: 44)
> +        Sets the Output Address Size in bits. The value set here must be less
> +        than or equal to the host SMMUv3's supported OAS, so that the
> +        intermediate physical addresses (IPA) consumed by host SMMU for stage-2
> +        translation do not exceed the host's max supported IPA size.
> +
> +    ``ssidsize=val`` (val between 0 and 20. default: 0)
> +        Sets the Substream ID size in bits. When set to a non-zero value,
> +        PASID capability is advertised to the vIOMMU and accelerated use cases
> +        such as Shared Virtual Addressing (SVA) are supported.
> +
>  ``-device amd-iommu[,option=...]``
>      Enables emulation of an AMD-Vi I/O Memory Management Unit (IOMMU).
>      Only available with ``-machine q35``, it supports the following options:
Besides,

Reviewed-by: Eric Auger <eric.auger@redhat.com>


Eric

RE: [PATCH v2 8/8] qemu-options.hx: Document arm-smmuv3 device's accel properties

[Shameer Kolothum Thodi]

> -----Original Message-----
> From: Nathan Chen <nathanc@nvidia.com>
> Sent: 12 March 2026 21:03
> To: qemu-devel@nongnu.org; qemu-arm@nongnu.org
> Cc: Eric Auger <eric.auger@redhat.com>; Peter Maydell
> <peter.maydell@linaro.org>; Michael S . Tsirkin <mst@redhat.com>; Igor
> Mammedov <imammedo@redhat.com>; Ani Sinha <anisinha@redhat.com>;
> Shannon Zhao <shannon.zhaosl@gmail.com>; Paolo Bonzini
> <pbonzini@redhat.com>; Daniel P . Berrangé <berrange@redhat.com>;
> Eduardo Habkost <eduardo@habkost.net>; Eric Blake <eblake@redhat.com>;
> Markus Armbruster <armbru@redhat.com>; Shameer Kolothum Thodi
> <skolothumtho@nvidia.com>; Nicolin Chen <nicolinc@nvidia.com>; Matt
> Ochs <mochs@nvidia.com>; Nathan Chen <nathanc@nvidia.com>
> Subject: [PATCH v2 8/8] qemu-options.hx: Document arm-smmuv3 device's
> accel properties
> 
> From: Nathan Chen <nathanc@nvidia.com>
> 
> Document arm-smmuv3 properties for setting HW-acceleration,
> Range Invalidation, and Address Translation Services support, as
> well as setting Output Address size and Substream ID size.
> 
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  qemu-options.hx | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 890c4f1d23..836de4532c 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1274,13 +1274,40 @@ SRST
>      ``aw-bits=val`` (val between 32 and 64, default depends on machine)
>          This decides the address width of the IOVA address space.
> 
> -``-device arm-smmuv3,primary-bus=id``
> +``-device arm-smmuv3,primary-bus=id[,option=...]``
>      This is only supported by ``-machine virt`` (ARM).
> 
>      ``primary-bus=id``
>          Accepts either the default root complex (pcie.0) or a
>          pxb-pcie based root complex.
> 
> +    ``accel=on|off`` (default: off)
> +        Enables guest to try to leverage host SMMUv3 features for acceleration.
> +        By default, enabling accel configures the host SMMUv3 in nested mode
> to
> +        support vfio-pci pass-through.

It might be worth mentioning that the properties below are only
applicable when accel=on.

Also, should we explicitly mention that "auto" is currently not
supported?

Thanks,
Shameer

> +
> +    ``ril=on|off`` (default: on)
> +        Support for Range Invalidation, which allows the SMMUv3 driver to
> +        invalidate TLB entries for a range of IOVAs at once instead of issuing
> +        separate commands to invalidate each page. Must match with host
> SMMUv3
> +        Range Invalidation support.
> +
> +    ``ats=on|off`` (default: off)
> +        Support for Address Translation Services, which enables PCIe devices to
> +        cache address translations in their local TLB and reduce latency. Host
> +        SMMUv3 must support ATS in order to enable this feature for the
> vIOMMU.
> +
> +    ``oas=val`` (supported values are 44 and 48. default: 44)
> +        Sets the Output Address Size in bits. The value set here must be less
> +        than or equal to the host SMMUv3's supported OAS, so that the
> +        intermediate physical addresses (IPA) consumed by host SMMU for
> stage-2
> +        translation do not exceed the host's max supported IPA size.
> +
> +    ``ssidsize=val`` (val between 0 and 20. default: 0)
> +        Sets the Substream ID size in bits. When set to a non-zero value,
> +        PASID capability is advertised to the vIOMMU and accelerated use cases
> +        such as Shared Virtual Addressing (SVA) are supported.
> +
>  ``-device amd-iommu[,option=...]``
>      Enables emulation of an AMD-Vi I/O Memory Management Unit (IOMMU).
>      Only available with ``-machine q35``, it supports the following options:
> --
> 2.43.0

Re: [PATCH v2 8/8] qemu-options.hx: Document arm-smmuv3 device's accel properties

[Nathan Chen]

On 3/16/2026 1:27 AM, Shameer Kolothum Thodi wrote:
> 
>> -----Original Message-----
>> From: Nathan Chen<nathanc@nvidia.com>
>> Sent: 12 March 2026 21:03
>> To:qemu-devel@nongnu.org;qemu-arm@nongnu.org
>> Cc: Eric Auger<eric.auger@redhat.com>; Peter Maydell
>> <peter.maydell@linaro.org>; Michael S . Tsirkin<mst@redhat.com>; Igor
>> Mammedov<imammedo@redhat.com>; Ani Sinha<anisinha@redhat.com>;
>> Shannon Zhao<shannon.zhaosl@gmail.com>; Paolo Bonzini
>> <pbonzini@redhat.com>; Daniel P . Berrangé<berrange@redhat.com>;
>> Eduardo Habkost<eduardo@habkost.net>; Eric Blake<eblake@redhat.com>;
>> Markus Armbruster<armbru@redhat.com>; Shameer Kolothum Thodi
>> <skolothumtho@nvidia.com>; Nicolin Chen<nicolinc@nvidia.com>; Matt
>> Ochs<mochs@nvidia.com>; Nathan Chen<nathanc@nvidia.com>
>> Subject: [PATCH v2 8/8] qemu-options.hx: Document arm-smmuv3 device's
>> accel properties
>>
>> From: Nathan Chen<nathanc@nvidia.com>
>>
>> Document arm-smmuv3 properties for setting HW-acceleration,
>> Range Invalidation, and Address Translation Services support, as
>> well as setting Output Address size and Substream ID size.
>>
>> Signed-off-by: Nathan Chen<nathanc@nvidia.com>
>> ---
>>   qemu-options.hx | 29 ++++++++++++++++++++++++++++-
>>   1 file changed, 28 insertions(+), 1 deletion(-)
>>
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 890c4f1d23..836de4532c 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -1274,13 +1274,40 @@ SRST
>>       ``aw-bits=val`` (val between 32 and 64, default depends on machine)
>>           This decides the address width of the IOVA address space.
>>
>> -``-device arm-smmuv3,primary-bus=id``
>> +``-device arm-smmuv3,primary-bus=id[,option=...]``
>>       This is only supported by ``-machine virt`` (ARM).
>>
>>       ``primary-bus=id``
>>           Accepts either the default root complex (pcie.0) or a
>>           pxb-pcie based root complex.
>>
>> +    ``accel=on|off`` (default: off)
>> +        Enables guest to try to leverage host SMMUv3 features for acceleration.
>> +        By default, enabling accel configures the host SMMUv3 in nested mode
>> to
>> +        support vfio-pci pass-through.
> It might be worth mentioning that the properties below are only
> applicable when accel=on.
> 
> Also, should we explicitly mention that "auto" is currently not
> supported?

Yes, I will mention accel=on being a requirement and call out that 
"auto" is currently not supported.

Thanks,
Nathan

Re: [PATCH v2 0/8] hw/arm/smmuv3-accel: Support AUTO properties

[Eric Auger]

Hi Nathan,

On 3/12/26 10:03 PM, Nathan Chen wrote:
> Hi,

If we want this to be taken in qemu 11.0 you need to clearly indicate
that in the series title:
using a subject prefix like "PATCH for-11.0"

Then you need to clearly justify what those patches are fixes for stuff
introduced in qemu 11.0, something like:

In qemu 11 we introduced new options for vSMMU but feedbacks received
when starting the integration of layered products shows the need for
auto/host retrieved values. To avoid breaking JSON/QMP compat, we want
to fix the option types so that they can later support the auto mode. At
the moment the auto mode is not supported though.

Thanks

Eric


> This is a follow-up to the previous RFC series [0] that introduces
> support for specifying 'auto' for arm-smmuv3 accelerated mode's ATS,
> RIL, SSIDSIZE, and OAS feature properties. Based on feedback from the
> previous mailing list discussion, this refresh only converts the
> properties to the auto form, keeping the default values from
> Shameer's HW-accel SMMUv3 series [1]. A future series will
> introduce support for resolving the 'auto' values based on host
> SMMUv3 IDR values, as well as setting per-device ATS capability.
>
> When set to 'auto', RIL and OAS will use the defaults set from
> smmuv3_init_id_regs() while ATS and SSIDSIZE will remain at the
> initialized 0 value; i.e. RIL enabled, 44-bit OAS, ATS support
> disabled, 0-bit SSIDSIZE.
>
> A complete branch can be found here:
> https://github.com/NathanChenNVIDIA/qemu/tree/smmuv3-accel-auto-v2
>
> Please take a look and let me know your feedback.
>
> Thanks,
> Nathan
>
> Changes from RFCv1:
> - Remove changes that resolve the 'auto' values based on host SMMUv3
> - Restore defaults values for RIL, OAS, SSIDSIZE, and ATS
> - Update OasMode to accept all OAS sizes instead of only auto, 44, and
>   48
> - Include comment in SsidSizeMode schema clarifying enum value
>   ordering
> - Replace ats-enabled prop with a helper that accepts the dynamic
>   casted TYPE_ARM_SMMUV3 object
> - Separate out guest vs. host ATS check in
>   smmuv3_accel_check_hw_compatible() to a different commit
> - Document accel, RIL, OAS, SSIDSIZE, and ATS properties in
>   qemu-options.hx
>
> Testing:
> Basic sanity testing was performed on an NVIDIA Grace platform with GPU
> device assignment and running CUDA test apps on the guest. Additional
> testing and feedback are welcome.
>
> [0] https://lore.kernel.org/qemu-devel/20260309192119.870186-1-nathanc@nvidia.com/
> [1] https://lore.kernel.org/all/20260126104342.253965-1-skolothumtho@nvidia.com/
>
> Nathan Chen (8):
>   hw/arm/smmuv3-accel: Check ATS compatibility between host and guest
>   hw/arm/smmuv3-accel: Change ATS property to OnOffAuto
>   hw/arm/smmuv3-accel: Change RIL property to OnOffAuto
>   qdev: Add a SsidSizeMode property
>   hw/arm/smmuv3-accel: Change SSIDSIZE property to SsidSizeMode
>   qdev: Add an OasMode property
>   hw/arm/smmuv3-accel: Change OAS property to OasMode
>   qemu-options.hx: Document arm-smmuv3 device's accel properties
>
>  hw/arm/smmuv3-accel.c                    | 42 ++++++++++++++++++----
>  hw/arm/smmuv3.c                          | 38 ++++++++++----------
>  hw/arm/virt-acpi-build.c                 |  2 +-
>  hw/core/qdev-properties-system.c         | 27 +++++++++++++++
>  include/hw/arm/smmuv3.h                  | 11 +++---
>  include/hw/core/qdev-properties-system.h |  6 ++++
>  qapi/misc-arm.json                       | 44 ++++++++++++++++++++++++
>  qapi/pragma.json                         |  1 +
>  qemu-options.hx                          | 29 +++++++++++++++-
>  9 files changed, 169 insertions(+), 31 deletions(-)
>

Re: [PATCH v2 0/8] hw/arm/smmuv3-accel: Support AUTO properties

[Peter Maydell]

On Mon, 16 Mar 2026 at 08:08, Eric Auger <eric.auger@redhat.com> wrote:
>
> Hi Nathan,
>
> On 3/12/26 10:03 PM, Nathan Chen wrote:
> > Hi,
>
> If we want this to be taken in qemu 11.0 you need to clearly indicate
> that in the series title:
> using a subject prefix like "PATCH for-11.0"
>
> Then you need to clearly justify what those patches are fixes for stuff
> introduced in qemu 11.0, something like:
>
> In qemu 11 we introduced new options for vSMMU but feedbacks received
> when starting the integration of layered products shows the need for
> auto/host retrieved values. To avoid breaking JSON/QMP compat, we want
> to fix the option types so that they can later support the auto mode. At
> the moment the auto mode is not supported though.

Yes. At the moment this is on my "look at it for 11.1" pile.
If you want it in 11.0 then it must very clearly state the
justfication (i.e. why it is not new feature work) and be
as small as possible to achieve its aim.

-- PMM

Re: [PATCH v2 0/8] hw/arm/smmuv3-accel: Support AUTO properties

[Nathan Chen]

Hi,

On 3/16/2026 3:05 AM, Peter Maydell wrote:
> On Mon, 16 Mar 2026 at 08:08, Eric Auger<eric.auger@redhat.com> wrote:
>> Hi Nathan,
>>
>> On 3/12/26 10:03 PM, Nathan Chen wrote:
>>> Hi,
>> If we want this to be taken in qemu 11.0 you need to clearly indicate
>> that in the series title:
>> using a subject prefix like "PATCH for-11.0"
>>
>> Then you need to clearly justify what those patches are fixes for stuff
>> introduced in qemu 11.0, something like:
>>
>> In qemu 11 we introduced new options for vSMMU but feedbacks received
>> when starting the integration of layered products shows the need for
>> auto/host retrieved values. To avoid breaking JSON/QMP compat, we want
>> to fix the option types so that they can later support the auto mode. At
>> the moment the auto mode is not supported though.
> Yes. At the moment this is on my "look at it for 11.1" pile.
> If you want it in 11.0 then it must very clearly state the
> justfication (i.e. why it is not new feature work) and be
> as small as possible to achieve its aim.

I see, I will send out another revision today with the correct prefix 
and justification for belonging in 11.0. I will keep these guidelines in 
mind for the future.

Thanks,
Nathan