KVM: x86 emulator: fix xchg instruction emulation
KVM: x86 emulator: fix xchg instruction emulation

If the destination is a memory operand and the memory cannot
map to a valid page, the xchg instruction emulation and locked
instruction will not work on io regions and stuck in endless
loop. We should emulate exchange as write to fix it.

Signed-off-by: Wei Yongjun <f52b9831d10c067ffbc33238e89e1e27651b0884@cn.fujitsu.com>
Acked-by: Gleb Natapov <03189597947f75187c4136ade35aec34feed9dc1@redhat.com>
Signed-off-by: Marcelo Tosatti <958bcd1f4a7a8c36dca09fe3fa9cb5f1483adf51@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs