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GET /api/patches/2226865/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "id": 2226865,
    "url": "http://patchwork.ozlabs.org/api/patches/2226865/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260422204335.23116-5-nathanc@nvidia.com/",
    "project": {
        "id": 14,
        "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api",
        "name": "QEMU Development",
        "link_name": "qemu-devel",
        "list_id": "qemu-devel.nongnu.org",
        "list_email": "qemu-devel@nongnu.org",
        "web_url": "",
        "scm_url": "",
        "webscm_url": "",
        "list_archive_url": "",
        "list_archive_url_format": "",
        "commit_url_format": ""
    },
    "msgid": "<20260422204335.23116-5-nathanc@nvidia.com>",
    "list_archive_url": null,
    "date": "2026-04-22T20:43:32",
    "name": "[v2,4/7] hw/arm/smmuv3-accel: Implement \"auto\" value for \"ssidsize\"",
    "commit_ref": null,
    "pull_url": null,
    "state": "new",
    "archived": false,
    "hash": "faa2e41cfa4d02455812bdca936f87a3f0617f7f",
    "submitter": {
        "id": 92820,
        "url": "http://patchwork.ozlabs.org/api/people/92820/?format=api",
        "name": "Nathan Chen",
        "email": "nathanc@nvidia.com"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260422204335.23116-5-nathanc@nvidia.com/mbox/",
    "series": [
        {
            "id": 501105,
            "url": "http://patchwork.ozlabs.org/api/series/501105/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=501105",
            "date": "2026-04-22T20:43:28",
            "name": "hw/arm/smmuv3-accel: Resolve AUTO properties",
            "version": 2,
            "mbox": "http://patchwork.ozlabs.org/series/501105/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/2226865/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/2226865/checks/",
    "tags": {},
    "related": [],
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        "From": "Nathan Chen <nathanc@nvidia.com>",
        "To": "qemu-arm@nongnu.org,\n\tqemu-devel@nongnu.org",
        "Cc": "Eric Auger <eric.auger@redhat.com>,\n Peter Maydell <peter.maydell@linaro.org>,\n Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, =?utf-8?q?Philippe_Mathieu-D?=\n\t=?utf-8?q?aud=C3=A9?= <philmd@linaro.org>,\n Yanan Wang <wangyanan55@huawei.com>, Zhao Liu <zhao1.liu@intel.com>,\n Shameer Kolothum <skolothumtho@nvidia.com>, Matt Ochs <mochs@nvidia.com>,\n Nicolin Chen <nicolinc@nvidia.com>, Nathan Chen <nathanc@nvidia.com>",
        "Subject": "[PATCH v2 4/7] hw/arm/smmuv3-accel: Implement \"auto\" value for\n \"ssidsize\"",
        "Date": "Wed, 22 Apr 2026 13:43:32 -0700",
        "Message-ID": "<20260422204335.23116-5-nathanc@nvidia.com>",
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    },
    "content": "Allow accelerated SMMUv3 SSID size property to be derived from host\nIOMMU capabilities. Derive host values using IOMMU_GET_HW_INFO,\nretrieving SSID size from IDR1. When the auto SSID size is resolved\nto a non-zero value, PASID capability is advertised to the vIOMMU\nand accelerated use cases such as Shared Virtual Addressing (SVA)\nare supported.\n\nSigned-off-by: Nathan Chen <nathanc@nvidia.com>\n---\n hw/arm/smmuv3-accel.c | 18 ++++++++++++++++--\n hw/arm/smmuv3.c       | 20 ++++++++++----------\n 2 files changed, 26 insertions(+), 12 deletions(-)",
    "diff": "diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c\nindex 98c2cdcb5e..d13d15a11d 100644\n--- a/hw/arm/smmuv3-accel.c\n+++ b/hw/arm/smmuv3-accel.c\n@@ -62,6 +62,12 @@ static void smmuv3_accel_auto_finalise(SMMUv3State *s,\n                                FIELD_EX32(info->idr[3], IDR3, RIL));\n     }\n \n+    if (s->ssidsize == SSID_SIZE_MODE_AUTO) {\n+        /* Store for get_viommu_flags() to determine PASID support */\n+        s->idr[1] = FIELD_DP32(s->idr[1], IDR1, SSIDSIZE,\n+                               FIELD_EX32(info->idr[1], IDR1, SSIDSIZE));\n+    }\n+\n     accel->auto_finalised = true;\n }\n \n@@ -822,6 +828,13 @@ static AddressSpace *smmuv3_accel_find_add_as(PCIBus *bus, void *opaque,\n     }\n }\n \n+static inline bool smmuv3_pasid_supported(SMMUv3State *s)\n+{\n+    return s->ssidsize > SSID_SIZE_MODE_0 ||\n+           (s->ssidsize == SSID_SIZE_MODE_AUTO &&\n+            FIELD_EX32(s->idr[1], IDR1, SSIDSIZE));\n+}\n+\n static uint64_t smmuv3_accel_get_viommu_flags(void *opaque)\n {\n     /*\n@@ -834,7 +847,7 @@ static uint64_t smmuv3_accel_get_viommu_flags(void *opaque)\n     SMMUState *bs = opaque;\n     SMMUv3State *s = ARM_SMMUV3(bs);\n \n-    if (s->ssidsize > SSID_SIZE_MODE_0) {\n+    if (smmuv3_pasid_supported(s)) {\n         flags |= VIOMMU_FLAG_PASID_SUPPORTED;\n     }\n     return flags;\n@@ -974,7 +987,8 @@ void smmuv3_accel_init(SMMUv3State *s)\n     smmuv3_accel_as_init(s);\n \n     if (s->ats == ON_OFF_AUTO_AUTO ||\n-        s->ril == ON_OFF_AUTO_AUTO) {\n+        s->ril == ON_OFF_AUTO_AUTO ||\n+        s->ssidsize == SSID_SIZE_MODE_AUTO) {\n         s->s_accel->auto_mode = true;\n     }\n \ndiff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c\nindex b7aa4122eb..07025245e2 100644\n--- a/hw/arm/smmuv3.c\n+++ b/hw/arm/smmuv3.c\n@@ -626,7 +626,10 @@ static int decode_ste(SMMUv3State *s, SMMUTransCfg *cfg,\n     }\n \n     /* Multiple context descriptors require SubstreamID support */\n-    if (s->ssidsize == SSID_SIZE_MODE_0 && STE_S1CDMAX(ste) != 0) {\n+    if ((s->ssidsize == SSID_SIZE_MODE_0 ||\n+         (s->ssidsize == SSID_SIZE_MODE_AUTO &&\n+          !FIELD_EX32(s->idr[1], IDR1, SSIDSIZE))) &&\n+        STE_S1CDMAX(ste) != 0) {\n         qemu_log_mask(LOG_UNIMP,\n                 \"SMMUv3: multiple S1 context descriptors require SubstreamID support. \"\n                 \"Configure ssidsize > 0 (requires accel=on)\\n\");\n@@ -1972,10 +1975,6 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)\n     }\n #endif\n \n-    if (s->ssidsize == SSID_SIZE_MODE_AUTO) {\n-        error_setg(errp, \"ssidsize auto mode is not supported\");\n-        return false;\n-    }\n     if (s->oas != OAS_MODE_44 && s->oas != OAS_MODE_48) {\n         error_setg(errp, \"QEMU SMMUv3 model only implements 44 and 48 bit\"\n                    \"OAS; other OasMode values are not supported\");\n@@ -1996,7 +1995,8 @@ static bool smmu_validate_property(SMMUv3State *s, Error **errp)\n             return false;\n         }\n         if (s->ssidsize > SSID_SIZE_MODE_0) {\n-            error_setg(errp, \"ssidsize can only be set if accel=on\");\n+            error_setg(errp, \"ssidsize can only be greater than 0 \"\n+                       \"bits if accel=on\");\n             return false;\n         }\n         return true;\n@@ -2177,11 +2177,11 @@ static void smmuv3_class_init(ObjectClass *klass, const void *data)\n         \"are 44 or 48 bits. Defaults to 44 bits. oas=auto is not \"\n         \"supported.\");\n     object_class_property_set_description(klass, \"ssidsize\",\n-        \"Number of bits used to represent SubstreamIDs (SSIDs). \"\n+        \"Set number of bits used to represent SubstreamIDs (SSIDs). \"\n+        \"Valid values are 0-20 and auto. Defaults to 0. \"\n         \"A value of N allows SSIDs in the range [0 .. 2^N - 1]. \"\n-        \"Valid range is 0-20, where 0 disables SubstreamID support. \"\n-        \"Defaults to 0. A value greater than 0 is required to enable \"\n-        \"PASID support. ssidsize=auto is not supported.\");\n+        \"A value of 0 disables SubstreamID support. A value greater \"\n+        \"than 0 is required to enable PASID support.\");\n }\n \n static int smmuv3_notify_flag_changed(IOMMUMemoryRegion *iommu,\n",
    "prefixes": [
        "v2",
        "4/7"
    ]
}