Re: [PATCH v2 02/10] KVM: define common __KVM_GUESTDBG_USE_SW/HW_BP values

Alex Bennée
2015-04-13T14:51:33Z

Christoffer Dall <christoffer.dall@linaro.org> writes:

> On Tue, Mar 31, 2015 at 04:08:00PM +0100, Alex Bennée wrote:
>> Currently x86, powerpc and soon arm64 use the same two architecture
>> specific bits for guest debug support for software and hardware
>> breakpoints. This makes the shared values explicit while leaving the
>> gate open for another architecture to use some other value if they
>> really really want to.
>>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>
>> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
>> index ab4d473..1731569 100644
>> --- a/arch/powerpc/include/uapi/asm/kvm.h
>> +++ b/arch/powerpc/include/uapi/asm/kvm.h
>> @@ -310,8 +310,8 @@ struct kvm_guest_debug_arch {
>> * and upper 16 bits are architecture specific. Architecture specific defines
>> * that ioctl is for setting hardware breakpoint or software breakpoint.
>> */
>> -#define KVM_GUESTDBG_USE_SW_BP 0x00010000
>> -#define KVM_GUESTDBG_USE_HW_BP 0x00020000
>> +#define KVM_GUESTDBG_USE_SW_BP __KVM_GUESTDBG_USE_SW_BP
>> +#define KVM_GUESTDBG_USE_HW_BP __KVM_GUESTDBG_USE_HW_BP
>>
>> /* definition of registers in kvm_run */
>> struct kvm_sync_regs {
>> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
>> index d7dcef5..1438202 100644
>> --- a/arch/x86/include/uapi/asm/kvm.h
>> +++ b/arch/x86/include/uapi/asm/kvm.h
>> @@ -250,8 +250,8 @@ struct kvm_debug_exit_arch {
>> __u64 dr7;
>> };
>>
>> -#define KVM_GUESTDBG_USE_SW_BP 0x00010000
>> -#define KVM_GUESTDBG_USE_HW_BP 0x00020000
>> +#define KVM_GUESTDBG_USE_SW_BP __KVM_GUESTDBG_USE_SW_BP
>> +#define KVM_GUESTDBG_USE_HW_BP __KVM_GUESTDBG_USE_HW_BP
>> #define KVM_GUESTDBG_INJECT_DB 0x00040000
>> #define KVM_GUESTDBG_INJECT_BP 0x00080000
>>
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 5eedf84..ce2db14 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -525,8 +525,16 @@ struct kvm_s390_irq {
>>
>> /* for KVM_SET_GUEST_DEBUG */
>>
>> -#define KVM_GUESTDBG_ENABLE 0x00000001
>> -#define KVM_GUESTDBG_SINGLESTEP 0x00000002
>> +#define KVM_GUESTDBG_ENABLE (1 << 0)
>> +#define KVM_GUESTDBG_SINGLESTEP (1 << 1)
>> +
>> +/*
>> + * Architecture specific stuff uses the top 16 bits of the field,
>
> can you be more specific than 'stuff' here? features?
>
>> + * however there is some shared commonality for the common cases
>
> I don't like this sentence; shared commonality is a pleonasm and the use
> of however makes it sounds like there's some caveat here.

OK I can see that - after I looked it up ;-)

> If the top 16 bits are indeed arhictecture specific, then I think they
> should just be defined in their architecture specific headers. Unless
> the idea here is that there's a fixed set of of flags that architectures
> can choose to support, in which case it should simply be defined in the
> common header.

Well an architecture might not support some features and want to use
those bits for something else? I didn't want to force the bottom two
of the architecture specific bits to wasted if the features don't exist.

>
>
>> + */
>> +#define __KVM_GUESTDBG_USE_SW_BP (1 << 16)
>> +#define __KVM_GUESTDBG_USE_HW_BP (1 << 17)
>> +
>>
>> struct kvm_guest_debug {
>> __u32 control;
>> --
>> 2.3.4
>>

--
Alex Bennée
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org