qemu currently returns 0 for rdmsr on invalid MSRs, and ignores wrmsr on invalid MSRs. Real x86 processors GPF on invalid MSRs, which allows software to detect unavailable MSRs. Emulate this behavior correctly in qemu.
Bug discovered via the BIOS Implementation Test Suite <http://biosbits.org/>; fix tested the same way, for both 32-bit and 64-bit x86. Signed-off-by: Josh Triplett <j...@joshtriplett.org> --- op_helper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -Naur a/target-i386/op_helper.c b/target-i386/op_helper.c --- a/target-i386/op_helper.c 2011-02-07 15:13:34.000000000 -0800 +++ b/target-i386/op_helper.c 2011-05-26 00:08:49.608636117 -0700 @@ -3135,7 +3135,7 @@ env->mce_banks[offset] = val; break; } - /* XXX: exception ? */ + raise_exception(EXCP0D_GPF); break; } } @@ -3266,7 +3266,7 @@ val = env->mce_banks[offset]; break; } - /* XXX: exception ? */ + raise_exception(EXCP0D_GPF); val = 0; break; }
