RE: [PATCH V4 01/10] iommufd: Support a HWPT without an iommu driver for noiommu

[Tian, Kevin]

> From: Jacob Pan <jacob.pan@xxxxxxxxxxxxxxxxxxx>
> Sent: Saturday, April 18, 2026 6:00 AM
> 
> Hi Kevin,
> 
> On Thu, 16 Apr 2026 07:25:57 +0000
> "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
> 
> > > From: Jacob Pan <jacob.pan@xxxxxxxxxxxxxxxxxxx>
> > > Sent: Wednesday, April 15, 2026 5:14 AM
> > >
> > > +	cfg.common.features =
> > > +		(BIT(PT_FEAT_DYNAMIC_TOP) |
> > > BIT(PT_FEAT_AMDV1_ENCRYPT_TABLES) |
> > > +		 BIT(PT_FEAT_AMDV1_FORCE_COHERENCE));
> >
> > PT_FEAT_AMDV1_ENCRYPT_TABLES is useless here.
> Technically yes but we need this flag to match forced features since we
> are sharing with the real AMDv1. Otherwise, this will fail with
> EOPNOTSUPP.
> static int pt_init_common(struct pt_common *common)
> {
> ...
> 	/* Requested features must match features compiled into this
> format */
> 	if ((common->features & ~(unsigned int)PT_SUPPORTED_FEATURES)
> ||
> 	    (!IS_ENABLED(CONFIG_DEBUG_GENERIC_PT) &&
> 	     (common->features & PT_FORCE_ENABLED_FEATURES) !=
> 		     PT_FORCE_ENABLED_FEATURES))
> 		return -EOPNOTSUPP;
> 
> where in iommu_amdv1.c:
> #define PT_FORCE_ENABLED_FEATURES
> \ (BIT(PT_FEAT_DYNAMIC_TOP) | BIT(PT_FEAT_AMDV1_ENCRYPT_TABLES) |
> \
> 	 BIT(PT_FEAT_AMDV1_FORCE_COHERENCE))

Okay, make sense.

btw iommufd selftest just removed the amdv1 format (will be in 7.1). then
let's not mention it in this series.