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.

Fixes: f7f5013a55a3 ("hw/arm/smmuv3-accel: Add support for ATS")
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 hw/arm/smmuv3-accel.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index 17306cd04b..2bb142c47f 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -101,6 +101,12 @@ 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

> -----Original Message-----
> From: Nathan Chen <nathanc@nvidia.com>
> Sent: 17 March 2026 18:38
> To: qemu-devel@nongnu.org; qemu-arm@nongnu.org
> Cc: Eric Auger <eric.auger@redhat.com>; Peter Maydell
> <peter.maydell@linaro.org>; Shannon Zhao <shannon.zhaosl@gmail.com>;
> Michael S . Tsirkin <mst@redhat.com>; Igor Mammedov
> <imammedo@redhat.com>; Ani Sinha <anisinha@redhat.com>; Paolo Bonzini
> <pbonzini@redhat.com>; Daniel P . Berrangé <berrange@redhat.com>; Eric
> Blake <eblake@redhat.com>; Markus Armbruster <armbru@redhat.com>;
> Shameer Kolothum Thodi <skolothumtho@nvidia.com>; Matt Ochs
> <mochs@nvidia.com>; Nicolin Chen <nicolinc@nvidia.com>; Nathan Chen
> <nathanc@nvidia.com>
> Subject: [PATCH v3 1/8] hw/arm/smmuv3-accel: Check ATS compatibility
> between host and guest
> 
> 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.
> 
> Fixes: f7f5013a55a3 ("hw/arm/smmuv3-accel: Add support for ATS")
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Nathan Chen <nathanc@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c index
> 17306cd04b..2bb142c47f 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -101,6 +101,12 @@
> 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;
> +    }

Reviewed-by: Shameer Kolothum <skolothumtho@nvidia.com>

Thanks,
Shameer