Re: [PATCH] target/ppc: Fix nested-hv HEAI delivery

[BALATON Zoltan]

On Fri, 5 May 2023, Nicholas Piggin wrote:
> ppc hypervisors turn HEAI interrupts into program interrupts injected
> into the guest that executed the illegal instruction, if the hypervisor
> doesn't handle it some other way.
>
> The nexted-hv implementation failed to account for this HEAI->program

Typo: nested-hv?

> conversion. The virtual hypervisor wants to see the HEAI when running
> a nested guest, so that interrupt type can be returned to its KVM
> caller.
>
> Fixes: 7cebc5db2eba6 ("target/ppc: Introduce a vhyp framework for nested HV 
> support")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> target/ppc/excp_helper.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 199328f4b6..a833efa8f9 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -1358,10 +1358,13 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int 
> excp)
>
>     /*
>      * We don't want to generate a Hypervisor Emulation Assistance
> -     * Interrupt if we don't have HVB in msr_mask (PAPR mode).
> +     * Interrupt if we don't have HVB in msr_mask (PAPR mode),
> +     * unless running a nested-hv guest, in which case the L1
> +     * kernel wants the interrupt.
>      */
>     if (excp == POWERPC_EXCP_HV_EMU && !(env->msr_mask & MSR_HVB)) {
> -        excp = POWERPC_EXCP_PROGRAM;
> +        if (!books_vhyp_handles_hv_excp(cpu))

You could instead write:

     if (excp == POWERPC_EXCP_HV_EMU && !(env->msr_mask & MSR_HVB) &&
         !books_vhyp_handles_hv_excp(cpu)) {

Regards.
BALATON Zoltan

> +            excp = POWERPC_EXCP_PROGRAM;
>     }
>
>     vector = env->excp_vectors[excp];