x86/pvh: Set phys_base when calling xen_prepare_pvh()

x86/pvh: Set phys_base when calling xen_prepare_pvh()

phys_base needs to be set for __pa() to work in xen_pvh_init() when
finding the hypercall page.  Set it before calling into
xen_prepare_pvh(), which calls xen_pvh_init().  Clear it afterward to
avoid __startup_64() adding to it and creating an incorrect value.

Signed-off-by: Jason Andryuk <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Message-ID: <20240823193630.2583107[email protected]>
Signed-off-by: Juergen Gross <[email protected]>