RE: [PATCH v4 4/5] common/domain: add a domain context record for shared_info...

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
[snip]
> > diff --git a/xen/common/domain.c b/xen/common/domain.c
> > index 7cc9526139..14e96c3bc2 100644
> > --- a/xen/common/domain.c
> > +++ b/xen/common/domain.c
> > @@ -33,6 +33,7 @@
> >   #include <xen/xenoprof.h>
> >   #include <xen/irq.h>
> >   #include <xen/argo.h>
> > +#include <xen/save.h>
> >   #include <asm/debugger.h>
> >   #include <asm/p2m.h>
> >   #include <asm/processor.h>
> > @@ -1649,6 +1650,64 @@ int continue_hypercall_on_cpu(
> >       return 0;
> >   }
> >
> > +static int save_shared_info(const struct domain *d, struct domain_context 
> > *c,
> > +                            bool dry_run)
> > +{
> > +    struct domain_shared_info_context ctxt = {
> > +#ifdef CONFIG_COMPAT
> > +        .flags = has_32bit_shinfo(d) ? DOMAIN_SAVE_32BIT_SHINFO : 0,
> > +#endif
> > +        .buffer_size = sizeof(shared_info_t),
> > +    };
> > +    size_t hdr_size = offsetof(typeof(ctxt), buffer);
> > +    int rc;
> > +
> > +    rc = DOMAIN_SAVE_BEGIN(SHARED_INFO, c, 0);
> > +    if ( rc )
> > +        return rc;
> > +
> > +    rc = domain_save_data(c, &ctxt, hdr_size);
> > +    if ( rc )
> > +        return rc;
> > +
> > +    rc = domain_save_data(c, d->shared_info, ctxt.buffer_size);
> > +    if ( rc )
> > +        return rc;
> > +
> > +    return domain_save_end(c);
> > +}
> > +
> > +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 || i ) /* expect only a single instance */
> > +        return rc;
> 
> This will return 0 if there is multiple instance. Is it intended?
> 

No, it ought to be an error... probably ENOENT.

> > +
> > +    rc = domain_load_data(c, &ctxt, hdr_size);
> > +    if ( rc )
> > +        return rc;
> > +
> > +    if ( ctxt.buffer_size != sizeof(shared_info_t) )
> > +        return -EINVAL;
> > +
> > +#ifdef CONFIG_COMPAT
> > +    has_32bit_shinfo(d) = ctxt.flags & DOMAIN_SAVE_32BIT_SHINFO;
> > +#endif
> Should we check the flag is not set when compat is not supported?
> 
> This would prevent someone to try restoring a compat shared info on a
> platform not support it.
> 

That would be prudent, yes. Probably a straight EINVAL for this one.

  Paul