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

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----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.

  Paul

> 
> Jan