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KVM: x86 emulator: fix xchg instruction emulation

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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 <yjwei@cn.fujitsu.com>
Acked-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Wei Yongjun 2010-07-15 08:51:58 +08:00 committed by Avi Kivity
parent 9195c4da26
commit c19b8bd60e
1 changed files with 4 additions and 0 deletions
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4
arch/x86/kvm/x86.c
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@ -3562,6 +3562,10 @@ static int emulator_cmpxchg_emulated(unsigned long addr,
goto emul_write;
page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
if (is_error_page(page)) {
kvm_release_page_clean(page);
goto emul_write;
}
kaddr = kmap_atomic(page, KM_USER0);
kaddr += offset_in_page(gpa);