Re: [PATCH 09/13] target/ppc: Prevent supervisor from modifying MSR[ME]

["Nicholas Piggin" <npiggin@gmail.com>]

On Tue Mar 12, 2024 at 8:27 PM AEST, Harsh Prateek Bora wrote:
>
>
> On 3/12/24 00:21, Nicholas Piggin wrote:
> > Prevent guest state modifying the MSR[ME] bit. Per ISA:
> > 
> >    An attempt to modify MSRME in privileged but non-hypervisor state is
>
> s/MSRME/MSR[ME] ?

Yes, thanks.

>
> >    ignored (i.e., the bit is not changed).
> > 
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> > ---
> >   target/ppc/helper_regs.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> > 
> > diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
> > index 410b39c231..25258986e3 100644
> > --- a/target/ppc/helper_regs.c
> > +++ b/target/ppc/helper_regs.c
> > @@ -264,6 +264,11 @@ int hreg_store_msr(CPUPPCState *env, target_ulong value, int alter_hv)
> >           value &= ~MSR_HVB;
> >           value |= env->msr & MSR_HVB;
> >       }
> > +    /* Attempt to modify MSR[ME] in guest state is ignored */
> > +    if (is_book3s_arch2x(env) && !(env->msr & MSR_HVB)) {
> > +        value &= ~(1 << MSR_ME);
> > +        value |= env->msr & (1 << MSR_ME);
> > +    }
>
> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
>
> >       if ((value ^ env->msr) & (R_MSR_IR_MASK | R_MSR_DR_MASK)) {
> >           cpu_interrupt_exittb(cs);
> >       }