From c19b8bd60e19308d5583ef200ddcc782d85d9543 Mon Sep 17 00:00:00 2001 From: Wei Yongjun Date: Thu, 15 Jul 2010 08:51:58 +0800 Subject: 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 Acked-by: Gleb Natapov Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/x86.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 689c2c3182a..97aab036dab 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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); -- cgit v1.2.3