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

[Richard Henderson <richard.henderson@linaro.org>]

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