Re: [PATCH v2] target/ppc: Fix BookE debug interrupt generation

[Cédric Le Goater]

On 4/21/22 03:17, Bin Meng wrote:
> From: Bin Meng <bin.meng@windriver.com>
>
> Per E500 core reference manual [1], chapter 8.4.4 "Branch Taken Debug
> Event" and chapter 8.4.5 "Instruction Complete Debug Event":
>
>    "A branch taken debug event occurs if both MSR[DE] and DBCR0[BRT]
>    are set ... Branch taken debug events are not recognized if MSR[DE]
>    is cleared when the branch instruction executes."
>
>    "An instruction complete debug event occurs when any instruction
>    completes execution so long as MSR[DE] and DBCR0[ICMP] are both
>    set ... Instruction complete debug events are not recognized if
>    MSR[DE] is cleared at the time of the instruction execution."
>
> Current codes do not check MSR.DE bit before setting HFLAGS_SE and
> HFLAGS_BE flag, which would cause the immediate debug interrupt to
> be generated, e.g.: when DBCR0.ICMP bit is set by guest software
> and MSR.DE is not set.
>
> [1] https://www.nxp.com/docs/en/reference-manual/E500CORERM.pdf
>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.

> ---
>
> Changes in v2:
> - update commit message to use E500CORERM instead of PowerISA 2.07
>
>   target/ppc/helper_regs.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
> index 9a691d6833..77bc57415c 100644
> --- a/target/ppc/helper_regs.c
> +++ b/target/ppc/helper_regs.c
> @@ -63,10 +63,10 @@ static uint32_t hreg_compute_hflags_value(CPUPPCState *env)
>   
>       if (ppc_flags & POWERPC_FLAG_DE) {
>           target_ulong dbcr0 = env->spr[SPR_BOOKE_DBCR0];
> -        if (dbcr0 & DBCR0_ICMP) {
> +        if ((dbcr0 & DBCR0_ICMP) && msr_de) {
>               hflags |= 1 << HFLAGS_SE;
>           }
> -        if (dbcr0 & DBCR0_BRT) {
> +        if ((dbcr0 & DBCR0_BRT) && msr_de) {
>               hflags |= 1 << HFLAGS_BE;
>           }
>       } else {