Re: [Xen-devel] [PATCH RFC v1 52/74] xen: mark xenstore/console pages as RAM and add them to dom_io

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.01.18 at 10:25, <roger.pau@xxxxxxxxxx> wrote:
> On Mon, Jan 08, 2018 at 06:49:21AM -0700, Jan Beulich wrote:
>> >>> On 04.01.18 at 14:06, <wei.liu2@xxxxxxxxxx> wrote:
>> > +void __init hypervisor_init_memory(void)
>> > +{
>> > +    uint64_t pfn = 0;
>> > +    long rc;
>> > +
>> > +    if ( !xen_guest )
>> > +        return;
>> > +
>> > +#define SHARE_PARAM(p) ({                                                 
>> >   \
>> > +    rc = xen_hypercall_hvm_get_param(p, &pfn);                            
>> >  \
>> > +    if ( rc )                                                             
>> >   \
>> > +        panic("Unable to get " #p);                                       
>> >   \
>> > +    share_xen_page_with_guest(mfn_to_page(pfn), dom_io, 
>> > XENSHARE_writable); \
>> 
>> Why dom_io rather than the client domain?
> 
> The client domain is not yet created at this point. This is exactly
> the same that Xen does for the low 1MiB for example.

The low 1Mb is being treated as MMIO, hence remains assigned
to dom_io.

>> The more that dom_io
>> pages can only be mapped by privileged guests (and hence I
>> assume you need another tweak somewhere this way).
> 
> I just use unshare_xen_page and share it again with the guest.

And there is no option of simply doing the sharing here later,
when the domain is already in existence?

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel