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                       | 15 +++++++++++++++
 qapi/pragma.json                         |  1 +
 4 files changed, 33 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..b372a3661b 100644
--- a/qapi/misc-arm.json
+++ b/qapi/misc-arm.json
@@ -45,3 +45,18 @@
 #                     { "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' ] }
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

Nathan Chen <nathanc@nvidia.com> writes:

> 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>

[...]

> diff --git a/qapi/misc-arm.json b/qapi/misc-arm.json
> index f921d740f1..b372a3661b 100644
> --- a/qapi/misc-arm.json
> +++ b/qapi/misc-arm.json
> @@ -45,3 +45,18 @@
>  #                     { "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
> +##

This renders like

    Enum SsidSizeMode (Since: 11.0)

       SMMUv3 SubstreamID size configuration mode.

       Values:
          * auto -- derive from host IOMMU capabilities

          * 0 -- Not documented

          * 1 -- Not documented

          * 2 -- Not documented

          * 3 -- Not documented

          * 4 -- Not documented

          * 5 -- Not documented

          * 6 -- Not documented

          * 7 -- Not documented

          * 8 -- Not documented

          * 9 -- Not documented

          * 10 -- Not documented

          * 11 -- Not documented

          * 12 -- Not documented

          * 13 -- Not documented

          * 14 -- Not documented

          * 15 -- Not documented

          * 16 -- Not documented

          * 17 -- Not documented

          * 18 -- Not documented

          * 19 -- Not documented

          * 20 -- Not documented

       Values 0-20: SSIDSIZE value in bits.  0 disables SubstreamID.

Sadly, many existing enums also have undocumented members.  Some because
documenting them one by one would be kind of silly (e.g. QKeyCode).

I don't have a better idea right now, so this is just an observation,
not a demand.  Maybe John Snow (cc'ed) can some day dream up a better
way to do this.

> +{ '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' ] }
> 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',