Re: [PATCH] target/arm: kvm64: remove a redundant KVM_CAP_SET_GUEST_DEBUG probe

[Richard Henderson]

On 11/22/23 02:15, Chao Du wrote:
> Hi,
>
> Kindly ping. :)
>
> Thanks,
> Chao
>
>
> > -----Original Messages-----From:"Chao Du" <duchao@eswincomputing.com>Sent 
> > Time:2023-10-25 15:07:26 (Wednesday)To:qemu-devel@nongnu.org, 
> > qemu-arm@nongnu.orgCc:Subject:[PATCH] target/arm: kvm64: remove a redundant 
> > KVM_CAP_SET_GUEST_DEBUG probe
> >
> > The KVM_CAP_SET_GUEST_DEBUG is probed during kvm_init().
> > gdbserver will fail to start if the CAP is not supported.
> > So no need to make another probe here, like other targets.
> >
> > Signed-off-by: Chao Du <duchao@eswincomputing.com>

Correct: all handled by kvm_supports_guest_debug.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~


> > ---
> >   target/arm/kvm64.c | 28 +++++++---------------------
> >   1 file changed, 7 insertions(+), 21 deletions(-)
> >
> > diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
> > index 4bb68646e4..b0bf59b5a1 100644
> > --- a/target/arm/kvm64.c
> > +++ b/target/arm/kvm64.c
> > @@ -31,13 +31,9 @@
> >   #include "hw/acpi/acpi.h"
> >   #include "hw/acpi/ghes.h"
> >   
> > -static bool have_guest_debug;
> >   
> >   void kvm_arm_init_debug(KVMState *s)
> >   {
> > -    have_guest_debug = kvm_check_extension(s,
> > -                                           KVM_CAP_SET_GUEST_DEBUG);
> > -
> >       max_hw_wps = kvm_check_extension(s, KVM_CAP_GUEST_DEBUG_HW_WPS);
> >       hw_watchpoints = g_array_sized_new(true, true,
> >                                          sizeof(HWWatchpoint), max_hw_wps);
> > @@ -1140,33 +1136,23 @@ static const uint32_t brk_insn = 0xd4200000;
> >   
> >   int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> >   {
> > -    if (have_guest_debug) {
> > -        if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) 
> > ||
> > -            cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&brk_insn, 4, 1)) {
> > -            return -EINVAL;
> > -        }
> > -        return 0;
> > -    } else {
> > -        error_report("guest debug not supported on this kernel");
> > +    if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) ||
> > +        cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&brk_insn, 4, 1)) {
> >           return -EINVAL;
> >       }
> > +    return 0;
> >   }
> >   
> >   int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> >   {
> >       static uint32_t brk;
> >   
> > -    if (have_guest_debug) {
> > -        if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&brk, 4, 0) ||
> > -            brk != brk_insn ||
> > -            cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 1)) 
> > {
> > -            return -EINVAL;
> > -        }
> > -        return 0;
> > -    } else {
> > -        error_report("guest debug not supported on this kernel");
> > +    if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&brk, 4, 0) ||
> > +        brk != brk_insn ||
> > +        cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 1)) {
> >           return -EINVAL;
> >       }
> > +    return 0;
> >   }
> >   
> >   /* See v8 ARM ARM D7.2.27 ESR_ELx, Exception Syndrome Register
> > --
> > 2.17.1