From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Jones <drjones@redhat.com>
Subject: Re: [PATCH 2/7] KVM: arm: guest debug, define API headers
Date: Wed, 26 Nov 2014 18:47:33 +0100
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Cc: Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>,
	kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org,
	marc.zyngier@arm.com, peter.maydell@linaro.org, agraf@suse.de,
	Catalin Marinas <catalin.marinas@arm.com>,
	jan.kiszka@siemens.com, Will Deacon <will.deacon@arm.com>,
	open list <linux-kernel@vger.kernel.org>,
	dahi@linux.vnet.ibm.com, r65777@freescale.com, bp@suse.de
To: Paolo Bonzini <pbonzini@redhat.com>
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On Wed, Nov 26, 2014 at 05:46:05PM +0100, Paolo Bonzini wrote:
>=20
>=20
> On 26/11/2014 15:58, Alex Benn=E9e wrote:
> >=20
> > Andrew Jones <drjones@redhat.com> writes:
> >=20
> >> On Tue, Nov 25, 2014 at 04:10:00PM +0000, Alex Benn=E9e wrote:
> >>> This commit defines the API headers for guest debugging. There ar=
e 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_SHI=
=46T)
> >>> +#define KVM_GUESTDBG_USE_HW_BP_SHIFT	17
> >>> +#define KVM_GUESTDBG_USE_HW_BP		(1 << KVM_GUESTDBG_USE_HW_BP_SHI=
=46T)
> >>> +
> >>
> >> 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?
> >=20
> > 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).
> >=20
> > But in principle I have no objection if other don't.
>=20
> I think it's a matter of personal taste.  "Architecture-specific" mea=
ns
> "not all architectures may support it", but it's certainly a good ide=
a
> to reuse the same value if multiple architectures do support a #defin=
e.
>=20
> What you did is fine, another possibility is to do
>=20
>     #define __KVM_GUESTDBG_USE_SW_BP   (1 << 16)
>=20
> in include/uapi/linux/kvm.h, and
>=20
>     #define KVM_GUESTDBG_USE_SW_BP __KVM_GUESTDBG_USE_SW_BP
>=20
> in the arch-specific file.  Andrew, is this closer to what you intend=
ed?
>

I just reread Documentation/virtual/kvm/api.txt a bit more closely and
see that these fall in the "architecture specific control" region of th=
e
field. So forget what I said. But your suggestion of __KVM_GUESTDBG_USE=
_SW_BP
looks like a good idea to me.

drew