Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754014AbbDNIYv (ORCPT ); Tue, 14 Apr 2015 04:24:51 -0400 Received: from mail-lb0-f179.google.com ([209.85.217.179]:36511 "EHLO mail-lb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753561AbbDNIYo (ORCPT ); Tue, 14 Apr 2015 04:24:44 -0400 Date: Tue, 14 Apr 2015 10:24:48 +0200 From: Christoffer Dall To: Alex =?iso-8859-1?Q?Benn=E9e?= Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, peter.maydell@linaro.org, agraf@suse.de, drjones@redhat.com, pbonzini@redhat.com, zhichao.huang@linaro.org, jan.kiszka@siemens.com, dahi@linux.vnet.ibm.com, r65777@freescale.com, bp@suse.de, Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "maintainer:X86 ARCHITECTURE..." , Gleb Natapov , Bharat Bhushan , Alexey Kardashevskiy , Mihai Caraman , Nadav Amit , "open list:LINUX FOR POWERPC..." , open list , "open list:ABI/API" Subject: Re: [PATCH v2 02/10] KVM: define common __KVM_GUESTDBG_USE_SW/HW_BP values Message-ID: <20150414082448.GR6186@cbox> References: <1427814488-28467-1-git-send-email-alex.bennee@linaro.org> <1427814488-28467-3-git-send-email-alex.bennee@linaro.org> <20150413115535.GM6186@cbox> <871tjokrnu.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <871tjokrnu.fsf@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3897 Lines: 89 On Mon, Apr 13, 2015 at 03:51:33PM +0100, Alex Benn?e wrote: > > Christoffer Dall writes: > > > On Tue, Mar 31, 2015 at 04:08:00PM +0100, Alex Benn?e 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 Benn?e > >> > >> 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. > In that case I think the definition is local to each architecture and should indeed just be duplicated. The __ definitions complicate more than they help as they are exported to userspace etc. The KVM maintainers may have a different view on this though. -Christoffer -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/