From mboxrd@z Thu Jan  1 00:00:00 1970
From: pbonzini@redhat.com (Paolo Bonzini)
Date: Wed, 26 Nov 2014 17:46:05 +0100
Subject: [PATCH 2/7] KVM: arm: guest debug, define API headers
In-Reply-To: <87sih6knzr.fsf@linaro.org>
References: <1416931805-23223-1-git-send-email-alex.bennee@linaro.org>
 <1416931805-23223-3-git-send-email-alex.bennee@linaro.org>
 <20141126143122.GB3245@hawk.usersys.redhat.com> <87sih6knzr.fsf@linaro.org>
Message-ID: <547603CD.6060708@redhat.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org



On 26/11/2014 15:58, Alex Benn?e wrote:
> 
> Andrew Jones <drjones@redhat.com> writes:
> 
>> On Tue, Nov 25, 2014 at 04:10:00PM +0000, Alex Benn?e wrote:
>>> This commit defines the API headers for guest debugging. There are two
>>> architecture specific debug structures:
> <snip>
>>> +/* Architecture related debug defines - upper 16 bits of
>>> + * kvm_guest_debug->control
>>> + */
>>> +#define KVM_GUESTDBG_USE_SW_BP_SHIFT	16
>>> +#define KVM_GUESTDBG_USE_SW_BP		(1 << KVM_GUESTDBG_USE_SW_BP_SHIFT)
>>> +#define KVM_GUESTDBG_USE_HW_BP_SHIFT	17
>>> +#define KVM_GUESTDBG_USE_HW_BP		(1 << KVM_GUESTDBG_USE_HW_BP_SHIFT)
>>> +
>>
>> I see this are defined in arch/x86/include/uapi/asm/kvm.h,
>> so you needed to reproduce them here, but shouldn't they
>> be promoted to include/uapi/linux/kvm.h instead?
> 
> Well if we move them to common uapi we either restrict the $ARCH
> specific options that don't have SW/HW BKPTS (would be weird but...) or
> make them generic in the lower 16 bits (breaks API).
> 
> But in principle I have no objection if other don't.

I think it's a matter of personal taste.  "Architecture-specific" means
"not all architectures may support it", but it's certainly a good idea
to reuse the same value if multiple architectures do support a #define.

What you did is fine, another possibility is to do

    #define __KVM_GUESTDBG_USE_SW_BP   (1 << 16)

in include/uapi/linux/kvm.h, and

    #define KVM_GUESTDBG_USE_SW_BP __KVM_GUESTDBG_USE_SW_BP

in the arch-specific file.  Andrew, is this closer to what you intended?

Paolo