If the RAX register has invalid bits set, a mov to CR8 instruction can raise a #GP. This has not been happening so far only because the compiler gods were good friends with the original author of the tests; but they did not like Thomas as well, and the test started failing with commit 19230e96697efa1e65a8945b6911a6eb4506d4e9 (Make vmx_tests.c compilable with -Wmissing-prototypes and -Wstrict-prototypes). Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> --- x86/vmx_tests.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c index 215953d..cbbb701 100644 --- a/x86/vmx_tests.c +++ b/x86/vmx_tests.c @@ -762,7 +762,7 @@ asm( "insn_cr3_load: mov cr3,%rax; mov %rax,%cr3;ret\n\t" "insn_cr3_store: mov %cr3,%rax;ret\n\t" #ifdef __x86_64__ - "insn_cr8_load: mov %rax,%cr8;ret\n\t" + "insn_cr8_load: xor %eax, %eax; mov %rax,%cr8;ret\n\t" "insn_cr8_store: mov %cr8,%rax;ret\n\t" #endif "insn_monitor: xor %eax, %eax; xor %ecx, %ecx; xor %edx, %edx; monitor;ret\n\t" -- 1.8.3.1
