Re: RIP register value in p2m_mem_access_check()

[Razvan Cojocaru <rzvncj@gmail.com>]

> That wouldn't match your observation (the two values were
> much farther apart), unless a call or jump got emulated.
>
> Further, after emulation, the user_regs.eip value should be the
> canonical one.

Well, I've downloaded and installed a fresh copy of Xen 4.2.0 from the 
official website, and added the printk() to p2m.c (the only modification 
I've done):

1311         req->vcpu_id = v->vcpu_id;
1312
1313         printk("v->arch.user_regs.eip: 0x%016lx, 
__vmread(GUEST_RIP):0x%016lx\n",
1314                v->arch.user_regs.eip, __vmread(GUEST_RIP));
1315     }

I then launched my guest VM, and tested it with the xen-access tool from 
tools/tests/xen-access, which I've run like this (1 is the machine ID, 
as printed out by 'sudo xm list'):

sudo ./xen-access 1 write

Here's what the hypervisor wrote (values that are different appear once 
per each VCPU):

(XEN) HVM1: Booting from 0000:7c00
(XEN) v->arch.user_regs.eip: 0x00000000fc002de9, 
__vmread(GUEST_RIP):0x0000000000007c17
(XEN) v->arch.user_regs.eip: 0x0000000000007c17, 
__vmread(GUEST_RIP):0x0000000000000667
(XEN) v->arch.user_regs.eip: 0x0000000000000667, 
__vmread(GUEST_RIP):0x0000000000000116
(XEN) v->arch.user_regs.eip: 0x0000000000000116, 
__vmread(GUEST_RIP):0x0000000000000116
(XEN) v->arch.user_regs.eip: 0x0000000000000116, 
__vmread(GUEST_RIP):0x00000000000005ab
(XEN) v->arch.user_regs.eip: 0x00000000000005ab, 
__vmread(GUEST_RIP):0x00000000000001e7
(XEN) v->arch.user_regs.eip: 0x00000000000001e7, 
__vmread(GUEST_RIP):0x00000000000001f3
(XEN) v->arch.user_regs.eip: 0x00000000000001f3, 
__vmread(GUEST_RIP):0x0000000000000b71
(XEN) v->arch.user_regs.eip: 0x0000000000000b71, 
__vmread(GUEST_RIP):0x0000000000000782
(XEN) v->arch.user_regs.eip: 0x0000000000000782, 
__vmread(GUEST_RIP):0x0000000000000782
(XEN) v->arch.user_regs.eip: 0x0000000000000782, 
__vmread(GUEST_RIP):0x0000000000000782

Not sure what's going on, but this time the only code I've added is the 
printk(). Any thoughts?


Thanks,
Razvan Cojocaru