Add a gva2gpa command purely for debug which performs
address translation on the gva, the existing gpa2hva
command can then also be used to find it in the qemu
userspace; e.g.

(qemu) info registers
.... RSP=ffffffff81c03e98
....
(qemu) gva2gpa 0xffffffff81c03e98
gpa: 0x1c03e98
(qemu) gpa2hva 0x1c03e98
Host virtual address for 0x1c03e98 (pc.ram) is 0x7f0599a03e98
(qemu) x/10x 0xffffffff81c03e98
ffffffff81c03e98: 0x81c03eb8 0xffffffff 0x8101ea3f 0xffffffff
ffffffff81c03ea8: 0x81d27b00 0xffffffff 0x00000000 0x00000000
ffffffff81c03eb8: 0x81c03ec8 0xffffffff

gdb -p ...qemu...
(gdb) x/10x 0x7f0599a03e98
0x7f0599a03e98:	0x81c03eb8	0xffffffff	0x8101ea3f	0xffffffff
0x7f0599a03ea8:	0x81d27b00	0xffffffff	0x00000000	0x00000000
0x7f0599a03eb8:	0x81c03ec8	0xffffffff
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190412152652.827-1-dgilbert@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>