On 5/14/2026 7:11 AM, Shameer Kolothum Thodi wrote:
-----Original Message-----
From: Nathan Chen<[email protected]>
Sent: 12 May 2026 20:35
To:[email protected];[email protected]
Cc: Eric Auger<[email protected]>; Peter Maydell
<[email protected]>; Philippe Mathieu-Daudé<[email protected]>;
Zhao Liu<[email protected]>; Matt Ochs<[email protected]>; Nicolin
Chen<[email protected]>; Shameer Kolothum Thodi
<[email protected]>; Nathan Chen<[email protected]>
Subject: [PATCH v3 2/7] hw/arm/smmuv3-accel: Implement "auto" value for
"ats"
From: Nathan Chen<[email protected]>
Allow accelerated SMMUv3 Address Translation Services support property
to be derived from host IOMMU capabilities. Derive host values using
IOMMU_GET_HW_INFO, retrieving ATS capability from IDR0.
Reviewed-by: Eric Auger<[email protected]>
Signed-off-by: Nathan Chen<[email protected]>
---
hw/arm/smmuv3-accel.c | 9 +++++++++
hw/arm/smmuv3.c | 11 ++++-------
2 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index 82c0800f4d..9fbd13c438 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -52,6 +52,11 @@ static void
smmuv3_accel_auto_finalise(SMMUv3State *s,
return;
}
+ if (s->ats == ON_OFF_AUTO_AUTO) {
+ s->idr[0] = FIELD_DP32(s->idr[0], IDR0, ATS,
+ FIELD_EX32(info->idr[0], IDR0, ATS));
+ }
+
accel->auto_finalised = true;
}
@@ -964,6 +969,10 @@ bool smmuv3_accel_init(SMMUv3State *s, Error
**errp)
bs->iommu_ops = &smmuv3_accel_ops;
smmuv3_accel_as_init(s);
+ if (s->ats == ON_OFF_AUTO_AUTO) {
+ s->s_accel->auto_mode = true;
+ }
+
if (s->s_accel->auto_mode) {
s->machine_done.notify = smmuv3_machine_done;
qemu_add_machine_init_done_notifier(&s->machine_done);
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 5c2855c377..e558f09652 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -1965,10 +1965,6 @@ static void smmu_reset_exit(Object *obj,
ResetType type)
static bool smmu_validate_property(SMMUv3State *s, Error **errp)
{
- if (s->ats == ON_OFF_AUTO_AUTO) {
- error_setg(errp, "ats auto mode is not supported");
- return false;
- }
if (s->ril == ON_OFF_AUTO_AUTO) {
error_setg(errp, "ril auto mode is not supported");
return false;
@@ -2170,9 +2166,10 @@ static void smmuv3_class_init(ObjectClass *klass,
const void *data)
"Disable range invalidation support (for accel=on). ril=auto "
"is not supported.");
object_class_property_set_description(klass, "ats",
- "Enable/disable ATS support (for accel=on). Please ensure host "
- "platform has ATS support before enabling this. ats=auto is not "
- "supported.");
+ "Enable/disable ATS support (for accel=on). "
+ "Valid values are on, off, and auto. Defaults to off. "
+ "Please ensure host platform supports ATS before setting it "
+ "to on.");
object_class_property_set_description(klass, "oas",
"Specify Output Address Size (for accel=on). Supported values "
"are 44 or 48 bits. Defaults to 44 bits. oas=auto is not "
In smmuv3.c we have;
case SMMU_CMD_ATC_INV:
{
SMMUDevice *sdev = smmu_find_sdev(bs, CMD_SID(&cmd));
if (!sdev || !s->ats) {
trace_smmuv3_unhandled_cmd(type);
break;
}
if (!smmuv3_accel_issue_inv_cmd(s, &cmd, sdev, errp)) {
cmd_error = SMMU_CERROR_ILL;
break;
}
break;
}
The above !s->ats will be true for AUTO case, right? I think
we should change the above check with smmuv3_ats_enabled().
Also, since we modified the ats to OnOffAuto in the previous
series, I am not sure the above should be a fix patch or not.
I see, I will use smmuv3_ats_enabled() here to account for the AUTO
case. I am not sure if it should have the Fixes tag either but let's see
if we can get any guidance on that point.
Thanks,
Nathan
