Re: [Qemu-devel] [RFC PATCH v3 2/7] target/ppc: Add ppc_get_trace_int_handler_addr

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 19/01/2019 01:07, Fabiano Rosas wrote:
> The upcoming single step functionality (KVM HV) needs to write to the
> Trace Interrupt handler's address for its mechanism to work. The
> address is calculated by applying an offset according to the value of
> the Alternate Interrupt Location (AIL) bits in the LPCR register.
> 
> Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
> ---
>  target/ppc/cpu.h         |  1 +
>  target/ppc/excp_helper.c | 12 ++++++++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 486abaf99b..2185ef5e67 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1256,6 +1256,7 @@ struct PPCVirtualHypervisorClass {
>      OBJECT_GET_CLASS(PPCVirtualHypervisorClass, (obj), \
>                       TYPE_PPC_VIRTUAL_HYPERVISOR)
>  
> +target_ulong ppc_get_trace_int_handler_addr(CPUState *cs);
>  void ppc_cpu_do_interrupt(CPUState *cpu);
>  bool ppc_cpu_exec_interrupt(CPUState *cpu, int int_req);
>  void ppc_cpu_dump_state(CPUState *cpu, FILE *f, fprintf_function cpu_fprintf,
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 337a3ef8bb..5d13d05c3b 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -746,6 +746,18 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
>      check_tlb_flush(env, false);
>  }
>  
> +target_ulong ppc_get_trace_int_handler_addr(CPUState *cs)
> +{
> +    PowerPCCPU *cpu = POWERPC_CPU(cs);
> +    CPUPPCState *env = &cpu->env;
> +    int ail;
> +
> +    ail = (env->spr[SPR_LPCR] & LPCR_AIL) >> LPCR_AIL_SHIFT;
> +    return env->excp_vectors[POWERPC_EXCP_TRACE] |
> +        ppc_excp_vector_offset(cs, ail);


This fails with:
cpu_abort(cs, "Invalid AIL combination %d\n", ail)

as @ail calculates as 0 when I am just about to start a guest and try to
set breakpoint at the initial $nip (set here:
https://git.qemu.org/?p=qemu.git;a=blob;f=hw/ppc/spapr_cpu_core.c;h=993759db47fa33b11a984c3043049297b06c0420;hb=38441756b70eec5807b5f60dad11a93a91199866#l90
)

This is long before h_set_mode is called.


> +}
> +
> +
>  void ppc_cpu_do_interrupt(CPUState *cs)
>  {
>      PowerPCCPU *cpu = POWERPC_CPU(cs);
> 

-- 
Alexey