> -----Original Message-----
> From: Julien Grall <[email protected]>
> Sent: 05 September 2019 21:21
> To: Paul Durrant <[email protected]>; [email protected]
> Cc: Alexandru Isaila <[email protected]>; Razvan Cojocaru
> <[email protected]>; Jan
> Beulich <[email protected]>; Stefano Stabellini <[email protected]>;
> Volodymyr Babchuk
> <[email protected]>; Andrew Cooper <[email protected]>;
> George Dunlap
> <[email protected]>; Ian Jackson <[email protected]>; Konrad
> Rzeszutek Wilk
> <[email protected]>; Tim (Xen.org) <[email protected]>; Wei Liu
> <[email protected]>; Roger Pau Monne
> <[email protected]>; Tamas K Lengyel <[email protected]>; Petre Pircalabu
> <[email protected]>
> Subject: Re: [PATCH v8 4/6] remove late (on-demand) construction of IOMMU
> page tables
>
> Hi,
>
> On 9/2/19 3:50 PM, Paul Durrant wrote:
> > diff --git a/tools/libxl/libxl_mem.c b/tools/libxl/libxl_mem.c
> > index 448a2af8fd..fd6f33312e 100644
> > --- a/tools/libxl/libxl_mem.c
> > +++ b/tools/libxl/libxl_mem.c
> > @@ -461,15 +461,17 @@ int libxl_domain_need_memory(libxl_ctx *ctx,
> > if (rc) goto out;
> >
> > *need_memkb = b_info->target_memkb;
> > + *need_memkb += b_info->shadow_memkb + b_info->iommu_memkb;
>
> AFAICT, iommu_memkb will be non-0 even when the IOMMU share the
> page-table with the CPUs. If so, why is this required for that case?
The toostack can't know about shared EPT as there's no mechanism to tell it.
Once patch #6 goes in though, the toolstack will be able to select shared and
forego the overhead. However, I've just realized that of course this means that
the domain may fail due to lack of resources on a host which doesn't support
shared EPT so I think I'm going to have to add add extra info (following on
from Roger's recent patch) so the toolstack can know whether shared EPT is
available.
Paul
>
> > +
> > switch (b_info->type) {
> > case LIBXL_DOMAIN_TYPE_PVH:
> > case LIBXL_DOMAIN_TYPE_HVM:
> > - *need_memkb += b_info->shadow_memkb + LIBXL_HVM_EXTRA_MEMORY;
> > + *need_memkb += LIBXL_HVM_EXTRA_MEMORY;
> > if (libxl_defbool_val(b_info->device_model_stubdomain))
> > *need_memkb += 32 * 1024;
> > break;
> > case LIBXL_DOMAIN_TYPE_PV:
> > - *need_memkb += b_info->shadow_memkb + LIBXL_PV_EXTRA_MEMORY;
> > + *need_memkb += LIBXL_PV_EXTRA_MEMORY;
> > break;
> > default:
> > rc = ERROR_INVAL;
> > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> > index b61399ce36..d94b7453cb 100644
> > --- a/tools/libxl/libxl_types.idl
> > +++ b/tools/libxl/libxl_types.idl
> > @@ -486,6 +486,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
> > ("target_memkb", MemKB),
> > ("video_memkb", MemKB),
> > ("shadow_memkb", MemKB),
> > + ("iommu_memkb", MemKB),
>
> I think you want a corresponding LIBXL_HAVE in libxl.h to tell external
> toolstack whether the field exist.
>
> > ("rtc_timeoffset", uint32),
> > ("exec_ssidref", uint32),
> > ("exec_ssid_label", string),
>
> Cheers,
>
> --
> Julien Grall
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