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Commit c19b8bd6 authored by Wei Yongjun's avatar Wei Yongjun Committed by Avi Kivity
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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: default avatarWei Yongjun <yjwei@cn.fujitsu.com>
Acked-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 9195c4da

arch/x86/kvm/x86.c

+4 −0
Original line number Original line Diff line number Diff line
@@ -3562,6 +3562,10 @@ static int emulator_cmpxchg_emulated(unsigned long addr, 
		goto emul_write;

		goto emul_write;





	page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);

	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 = kmap_atomic(page, KM_USER0);

	kaddr += offset_in_page(gpa);

	kaddr += offset_in_page(gpa);