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

[Harsh Prateek Bora <harshpb@linux.ibm.com>]

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] ?

>    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);
>       }