| Message ID | 497DDBA7.1040103@siemens.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Mon, Jan 26, 2009 at 1:49 PM, Jan Kiszka <jan.kiszka@siemens.com> wrote: > Hi, > > this line almost ruined my afternoon: There's a lesson for us to learn here: Always hack at night. > > diff --git a/qemu/qemu-kvm-x86.c b/qemu/qemu-kvm-x86.c > index 01748ed..4ad386b 100644 > --- a/qemu/qemu-kvm-x86.c > +++ b/qemu/qemu-kvm-x86.c > @@ -429,7 +429,6 @@ void kvm_arch_save_regs(CPUState *env) > env->cc_src = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C); > env->df = 1 - (2 * ((env->eflags >> 10) & 1)); > env->cc_op = CC_OP_EFLAGS; > - env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C); > > /* msrs */ > n = 0; > > The guest flags reported via gdb or monitor were garbage and I first > didn't realized this... > > git logs revealed that commit 6eecdc3eea74ead3c11b8b43d825d2cabe7a2456 > once introduced it mid of 2006, but maybe under different boundary > conditions. At least today it appears to be plain wrong, eflags must > always contain to full state, cc_src, df & cc_op are just supplementary > states. Please correct me if I'm wrong, otherwise I will send out a > proper patch, also upstream as QEMU's kvm suffers from the same issue. > > Jan Have you tested this removing the other parts of it too? I'd say there are unnecessary, and might well be harming other loads too. There were once a time in which we executed kvm from inside qemu's cpu_exec loop. Back then, it made some sense to mess with qemu flags. Right now, I don't see any reason for us to ever touch it.
diff --git a/qemu/qemu-kvm-x86.c b/qemu/qemu-kvm-x86.c index 01748ed..4ad386b 100644 --- a/qemu/qemu-kvm-x86.c +++ b/qemu/qemu-kvm-x86.c @@ -429,7 +429,6 @@ void kvm_arch_save_regs(CPUState *env) env->cc_src = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C); env->df = 1 - (2 * ((env->eflags >> 10) & 1)); env->cc_op = CC_OP_EFLAGS; - env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C); /* msrs */ n = 0;