Peter Maydell <peter.maydell@xxxxxxxxxx> writes:
> On 20 November 2015 at 15:05, Peter Maydell <peter.maydell@xxxxxxxxxx> wrote:
>> On 12 November 2015 at 16:20, Alex Bennée <alex.bennee@xxxxxxxxxx> wrote:
>>> As we haven't always had guest debug support we need to probe for it.
>>> Additionally we don't do this in the start-up capability code so we
>>> don't fall over on old kernels.
>>>
>>> Signed-off-by: Alex Bennée <alex.bennee@xxxxxxxxxx>
>>> ---
>>> target-arm/kvm64.c | 18 ++++++++++++++++++
>>> 1 file changed, 18 insertions(+)
>>>
>>> diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
>>> index ceebfeb..d087794 100644
>>> --- a/target-arm/kvm64.c
>>> +++ b/target-arm/kvm64.c
>>> @@ -25,6 +25,22 @@
>>> #include "internals.h"
>>> #include "hw/arm/arm.h"
>>>
>>> +static bool have_guest_debug;
>>> +
>>> +/**
>>> + * kvm_arm_init_debug()
>>> + * @cs: CPUState
>>> + *
>>> + * Check for guest debug capabilities.
>>> + *
>>> + */
>>> +static void kvm_arm_init_debug(CPUState *cs)
>>> +{
>>> + have_guest_debug = kvm_check_extension(cs->kvm_state,
>>> + KVM_CAP_SET_GUEST_DEBUG);
>>> + return;
>>> +}
>>> +
>>> static inline void set_feature(uint64_t *features, int feature)
>>> {
>>> *features |= 1ULL << feature;
>>> @@ -121,6 +137,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
>>> }
>>> cpu->mp_affinity = mpidr & ARM64_AFFINITY_MASK;
>>>
>>> + kvm_arm_init_debug(cs);
>>> +
>>> return kvm_arm_init_cpreg_list(cpu);
>>> }
>>
>> I assume in practice the kernel guarantees that either all
>> CPUs have the SET_GUEST_DEBUG cap, or none do :-)
>>
>> Reviewed-by: Peter Maydell <peter.maydell@xxxxxxxxxx>
>
> ...except I've just noticed that nothing else in this patchset
> ever reads the have_guest_debug bool we just set, so what is
> the purpose of this patch?
Oops, maybe to point out my stupidity ;-)
But yes the SET_GUEST_DEBUG cap is kernel wide.
>
> thanks
> -- PMM
--
Alex Bennée
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