RIP register value in p2m_mem_access_check()

[Razvan Cojocaru <rzvncj@gmail.com>]

Hello again,

simple test case: added the following statement in 
xen/arch/x86/mm/p2m.c, in function p2m_mem_access_check():

printk("v->arch.user_regs.eip: 0x%016lx, __vmread(GUEST_RIP): 
0x%016lx\n", v->arch.user_regs.eip, __vmread(GUEST_RIP));

(where v is current) which dutifully prints out (at the first page fault):

(XEN) v->arch.user_regs.eip: 0xfffff80002c13a7b, __vmread(GUEST_RIP): 
0xfffff8000269ec0a

They're not equal, and furthermore __vmread(GUEST_RIP) is the correct 
one (the same value returned by xc_domain_hvm_getcontext_partial()).

The questions:

1. What's the Xen-friendliest way to retrieve the _correct_ values for 
RIP and all the other registers usually put in a struct hvm_hw_cpu 
instance, in p2m_mem_access_check()?

2. What's the explanation for why things run as they do now?


Thanks,
Razvan Cojocaru