Re: [EXTERNAL] [PATCH v1 1/3] target/ppc: Fix POWER9 radix guest HV interrupt AIL behaviour

[Cédric Le Goater]

On 4/13/21 2:54 PM, Nicholas Piggin wrote:
> ISA v3.0 radix guest execution has a quirk in AIL behaviour such that
> the LPCR[AIL] value can apply to hypervisor interrupts.

Shouldn't we test for P9 ? But I think you are using a new exception 
model for P10 in the next patch. 

I guess it's ok for now.

> 
> This affects machines that emulate HV=1 mode (i.e., powernv9).
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  target/ppc/excp_helper.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 85de7e6c90..b8881c0f85 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -791,14 +791,23 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int 
> excp_model, int excp)
>  #endif
> 
>      /*
> -     * AIL only works if there is no HV transition and we are running
> -     * with translations enabled
> +     * AIL only works if MSR[IR] and MSR[DR] are both enabled.
>       */
> -    if (!((msr >> MSR_IR) & 1) || !((msr >> MSR_DR) & 1) ||
> -        ((new_msr & MSR_HVB) && !(msr & MSR_HVB))) {
> +    if (!((msr >> MSR_IR) & 1) || !((msr >> MSR_DR) & 1)) {
>          ail = 0;
>      }
> 
> +    /*
> +     * AIL does not work if there is a MSR[HV] 0->1 transition and the
> +     * partition is in HPT mode. For radix guests, such interrupts are
> +     * allowed to be delivered to the hypervisor in ail mode.
> +     */
> +    if ((new_msr & MSR_HVB) && !(msr & MSR_HVB)) {
> +        if (!(env->spr[SPR_LPCR] & LPCR_HR)) {

We have a ppc64_v3_radix() helper but this is minor.

C.

> +            ail = 0;
> +        }
> +    }
> +
>      vector = env->excp_vectors[excp];
>      if (vector == (target_ulong)-1ULL) {
>          cpu_abort(cs, "Raised an exception without defined vector %d\n",
>