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

On Sun, Aug 02, 2026 at 04:05:08PM +0000, Clément MATHIEU--DRIF wrote:
> SVM in Linux requires SMPWC as of 780dfed68862.

And what is 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]>
> ---
>  hw/i386/intel_iommu.c          | 3 ++-
>  hw/i386/intel_iommu_internal.h | 1 +
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> 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 */
> -- 
> 2.54.0