Re: [PATCH v1] intel_iommu: Expose SMPWC when SVM is enabled

On Tue, 2026-08-04 at 16:48 +0800, Yi Liu wrote:
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> 
> 
> On 8/3/26 00:05, Clément MATHIEU--DRIF wrote:
> 
> > SVM in Linux requires SMPWC as of 780dfed68862. This is free in the
> > current implementation as it is already in line with the expected
> > behaviour.
> > 
> > Signed-off-by: Clement Mathieu--Drif <[[email protected]](mailto:[email protected])>
> > ---
> >   hw/i386/intel_iommu.c          | 3 ++-
> >   hw/i386/intel_iommu_internal.h | 1 +
> >   2 files changed, 3 insertions(+), 1 deletion(-)
> 
> 
> Is it a fix tag needed?

Not sure, but we can add one in order to be consistent with the kernel commit.

> 
> 
> > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> > index 8245452d89..9f21622a4f 100644
> > --- a/hw/i386/intel_iommu.c
> > +++ b/hw/i386/intel_iommu.c
> > @@ -5108,7 +5108,8 @@ static void vtd_init(IntelIOMMUState *s)
> >       }
> > 
> >       if (s->svm) {
> > -        s->ecap |= VTD_ECAP_PRS | VTD_ECAP_PDS | VTD_ECAP_NWFS;
> > +        s->ecap |= VTD_ECAP_PRS | VTD_ECAP_PDS | VTD_ECAP_NWFS |
> > +                   VTD_ECAP_SMPWCS;
> >       }
> > 
> >       vtd_reset_caches(s);
> > diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> > index 924e91cb8a..df7a0efa6e 100644
> > --- a/hw/i386/intel_iommu_internal.h
> > +++ b/hw/i386/intel_iommu_internal.h
> > @@ -202,6 +202,7 @@
> >   #define VTD_ECAP_SMTS               (1ULL << 43)
> >   #define VTD_ECAP_SSTS               (1ULL << 46)
> >   #define VTD_ECAP_FSTS               (1ULL << 47)
> > +#define VTD_ECAP_SMPWCS             (1ULL << 48)
> > 
> >   /* CAP_REG */
> >   /* (offset >> 4) << 24 */
> 
>