RE: [PATCH v7 7/9] common/domain: add a domain context record for shared_info...

["Durrant, Paul" <pdurrant@xxxxxxxxxxxx>]

> -----Original Message-----
> From: Paul Durrant <xadimgnik@xxxxxxxxx>
> Sent: 04 September 2020 18:30
> To: 'Jan Beulich' <jbeulich@xxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Durrant, Paul <pdurrant@xxxxxxxxxxxx>; 
> 'Ian Jackson'
> <ian.jackson@xxxxxxxxxxxxx>; 'Wei Liu' <wl@xxxxxxx>; 'Andrew Cooper' 
> <andrew.cooper3@xxxxxxxxxx>;
> 'George Dunlap' <george.dunlap@xxxxxxxxxx>; 'Julien Grall' <julien@xxxxxxx>; 
> 'Stefano Stabellini'
> <sstabellini@xxxxxxxxxx>
> Subject: RE: [EXTERNAL] [PATCH v7 7/9] common/domain: add a domain context 
> record for shared_info...
> 
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> 
> 
> > -----Original Message-----
> > From: Jan Beulich <jbeulich@xxxxxxxx>
> > Sent: 26 August 2020 14:58
> > To: Paul Durrant <paul@xxxxxxx>
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Paul Durrant <pdurrant@xxxxxxxxxx>; Ian 
> > Jackson
> > <ian.jackson@xxxxxxxxxxxxx>; Wei Liu <wl@xxxxxxx>; Andrew Cooper 
> > <andrew.cooper3@xxxxxxxxxx>; George
> > Dunlap <george.dunlap@xxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Stefano 
> > Stabellini
> > <sstabellini@xxxxxxxxxx>
> > Subject: Re: [PATCH v7 7/9] common/domain: add a domain context record for 
> > shared_info...
> >
> > On 18.08.2020 12:30, Paul Durrant wrote:
> > > v7:
> > >  - Only restore vcpu_info and arch sub-structures for PV domains, to match
> > >    processing of SHARED_INFO in xc_sr_restore_x86_pv.c
> >
> > Since you point out this original logic, ...
> >
> > > +static int load_shared_info(struct domain *d, struct domain_context *c)
> > > +{
> > > +    struct domain_shared_info_context ctxt;
> > > +    size_t hdr_size = offsetof(typeof(ctxt), buffer);
> > > +    unsigned int i;
> > > +    int rc;
> > > +
> > > +    rc = DOMAIN_LOAD_BEGIN(SHARED_INFO, c, &i);
> > > +    if ( rc )
> > > +        return rc;
> > > +
> > > +    if ( i ) /* expect only a single instance */
> > > +        return -ENXIO;
> > > +
> > > +    rc = domain_load_data(c, &ctxt, hdr_size);
> > > +    if ( rc )
> > > +        return rc;
> > > +
> > > +    if ( ctxt.buffer_size > sizeof(shared_info_t) ||
> > > +         (ctxt.flags & ~DOMAIN_SAVE_32BIT_SHINFO) )
> > > +        return -EINVAL;
> > > +
> > > +    if ( ctxt.flags & DOMAIN_SAVE_32BIT_SHINFO )
> > > +    {
> > > +#ifdef CONFIG_COMPAT
> > > +        has_32bit_shinfo(d) = true;
> > > +#else
> > > +        return -EINVAL;
> > > +#endif
> > > +    }
> > > +
> > > +    if ( is_pv_domain(d) )
> > > +    {
> > > +        shared_info_t *shinfo = xmalloc(shared_info_t);
> > > +
> > > +        rc = domain_load_data(c, shinfo, sizeof(*shinfo));
> > > +        if ( rc )
> > > +        {
> > > +            xfree(shinfo);
> > > +            return rc;
> > > +        }
> > > +
> > > +#ifdef CONFIG_COMPAT
> > > +        if ( has_32bit_shinfo(d) )
> > > +        {
> > > +            memcpy(&d->shared_info->compat.vcpu_info,
> > > +                   &shinfo->compat.vcpu_info,
> > > +                   sizeof(d->shared_info->compat.vcpu_info));
> > > +            memcpy(&d->shared_info->compat.arch,
> > > +                   &shinfo->compat.arch,
> > > +                   sizeof(d->shared_info->compat.vcpu_info));
> > > +        }
> > > +        else
> > > +        {
> > > +            memcpy(&d->shared_info->native.vcpu_info,
> > > +                   &shinfo->native.vcpu_info,
> > > +                   sizeof(d->shared_info->native.vcpu_info));
> > > +            memcpy(&d->shared_info->native.arch,
> > > +                   &shinfo->native.arch,
> > > +                   sizeof(d->shared_info->native.arch));
> > > +        }
> > > +#else
> > > +        memcpy(&d->shared_info->vcpu_info,
> > > +               &shinfo->vcpu_info,
> > > +               sizeof(d->shared_info->vcpu_info));
> > > +        memcpy(&d->shared_info->arch,
> > > +               &shinfo->arch,
> > > +               sizeof(d->shared_info->shared));
> > > +#endif
> >
> > ... where does the rest of that logic (resetting of
> > arch.pfn_to_mfn_frame_list_list, evtchn_pending, evtchn_mask, and
> > evtchn_pending_sel) get done? Or why is it not needed anymore?
> 
> The resetting logic is still in xc_sr_restore_x86_pv.c (see patch #6). It's 
> going to need to stay
> there anyway to deal with older streams so I made it common to both cases; it 
> seems slightly separate
> from restoring the shared info.
> 

Actually I've changed my mind on this one; I'll do the zeroing here and leave 
the old SHARED_INFO record restore code alone.

  Paul

>   Paul
> 
> >
> > Jan