From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [RFC PATCH 08/16] KVM: arm64: Support dynamically hideable system registers Date: Wed, 25 Jul 2018 16:41:44 +0100 Message-ID: <877eljtj9j.fsf@linaro.org> References: <1529593060-542-1-git-send-email-Dave.Martin@arm.com> <1529593060-542-9-git-send-email-Dave.Martin@arm.com> <878t5ztneo.fsf@linaro.org> <20180725143613.GM4240@e103592.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3E33C40A50 for ; Wed, 25 Jul 2018 11:41:48 -0400 (EDT) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id A3VgXL7Wsdes for ; Wed, 25 Jul 2018 11:41:47 -0400 (EDT) Received: from mail-wr1-f67.google.com (mail-wr1-f67.google.com [209.85.221.67]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 4048540493 for ; Wed, 25 Jul 2018 11:41:47 -0400 (EDT) Received: by mail-wr1-f67.google.com with SMTP id b15-v6so7842014wrv.10 for ; Wed, 25 Jul 2018 08:41:47 -0700 (PDT) In-reply-to: <20180725143613.GM4240@e103592.cambridge.arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Dave Martin Cc: Okamoto Takayuki , Christoffer Dall , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu CkRhdmUgTWFydGluIDxEYXZlLk1hcnRpbkBhcm0uY29tPiB3cml0ZXM6Cgo+IE9uIFdlZCwgSnVs IDI1LCAyMDE4IGF0IDAzOjEyOjE1UE0gKzAxMDAsIEFsZXggQmVubsOpZSB3cm90ZToKPj4KPj4g RGF2ZSBNYXJ0aW4gPERhdmUuTWFydGluQGFybS5jb20+IHdyaXRlczoKPj4KPj4gPiBTb21lIHN5 c3RlbSByZWdpc3RlcnMgbWF5IG9yIG1heSBub3QgbG9naWNhbGx5IGV4aXN0IGZvciBhIHZjcHUK 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cm1AbGlzdHMuY3MuY29sdW1iaWEuZWR1Cmh0dHBzOi8vbGlzdHMuY3MuY29sdW1iaWEuZWR1L21h aWxtYW4vbGlzdGluZm8va3ZtYXJtCg== From mboxrd@z Thu Jan 1 00:00:00 1970 From: alex.bennee@linaro.org (Alex =?utf-8?Q?Benn=C3=A9e?=) Date: Wed, 25 Jul 2018 16:41:44 +0100 Subject: [RFC PATCH 08/16] KVM: arm64: Support dynamically hideable system registers In-Reply-To: <20180725143613.GM4240@e103592.cambridge.arm.com> References: <1529593060-542-1-git-send-email-Dave.Martin@arm.com> <1529593060-542-9-git-send-email-Dave.Martin@arm.com> <878t5ztneo.fsf@linaro.org> <20180725143613.GM4240@e103592.cambridge.arm.com> Message-ID: <877eljtj9j.fsf@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Dave Martin writes: > On Wed, Jul 25, 2018 at 03:12:15PM +0100, Alex Benn?e wrote: >> >> Dave Martin writes: >> >> > Some system registers may or may not logically exist for a vcpu >> > depending on whether certain architectural features are enabled for >> > the vcpu. >> > >> > In order to avoid spuriously emulating access to these registers >> > when they should not exist, or allowing the registers to be >> > spuriously enumerated or saved/restored through the ioctl >> > interface, a means is needed to allow registers to be hidden >> > depending on the vcpu configuration. >> > >> > In order to support this in a flexible way, this patch adds a >> > check_present() method to struct sys_reg_desc, and updates the >> > generic system register access and enumeration code to be aware of >> > it: if check_present() returns false, the code behaves as if the >> > register did not exist. >> > >> > For convenience, the complete check is wrapped up in a new helper >> > sys_reg_present(). >> > >> > An attempt has been made to hook the new check into the generic >> > accessors for trapped system registers. This should reduce the >> > potential for future surprises, although the redundant check will >> > add a small cost. No system register depends on this functionality >> > yet, and some paths needing the check may also need attention. >> > >> > Naturally, this facility makes sense only for registers that are >> > trapped. >> > >> > Signed-off-by: Dave Martin >> > --- >> > arch/arm64/kvm/sys_regs.c | 20 +++++++++++++++----- >> > arch/arm64/kvm/sys_regs.h | 11 +++++++++++ >> > 2 files changed, 26 insertions(+), 5 deletions(-) > > [...] > >> > diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h >> > index cd710f8..dfbb342 100644 >> > --- a/arch/arm64/kvm/sys_regs.h >> > +++ b/arch/arm64/kvm/sys_regs.h >> > @@ -22,6 +22,9 @@ >> > #ifndef __ARM64_KVM_SYS_REGS_LOCAL_H__ >> > #define __ARM64_KVM_SYS_REGS_LOCAL_H__ >> > >> > +#include >> > +#include >> >> I can see why you want compiler.h, but why types.h? > > For bool (though it felt a bit pedantic). It must be picked up elsewhere because it didn't fail when I rebuilt without it - and the header has been happily using bool up to that point. > > Cheers > ---Dave -- Alex Benn?e