From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Murzin Subject: Re: [PATCH v3 1/8] arm64: KVM: Use static keys for selecting the GIC backend Date: Fri, 9 Sep 2016 14:45:15 +0100 Message-ID: <57D2BCEB.3030306@arm.com> References: <1473350810-10857-1-git-send-email-vladimir.murzin@arm.com> <1473350810-10857-2-git-send-email-vladimir.murzin@arm.com> <57D27EA7.2040500@arm.com> <57D281F1.5000902@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 012144113E for ; Fri, 9 Sep 2016 09:36:47 -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 lslf3tIutlqP for ; Fri, 9 Sep 2016 09:36:45 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B0D4840F9B for ; Fri, 9 Sep 2016 09:36:45 -0400 (EDT) In-Reply-To: <57D281F1.5000902@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: Marc Zyngier , kvmarm@lists.cs.columbia.edu Cc: andre.przywara@arm.com, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu On 09/09/16 10:33, Vladimir Murzin wrote: > Hi Marc, > = > On 09/09/16 10:19, Marc Zyngier wrote: >> > Hi Vladimir, >> > = > ... >>> >> = >>> >> +extern struct static_key_false kvm_gicv3_cpuif; >> > = >> > I think we should follow the model set by kvm_vgic_global_state, which >> > is declared in arm_vgic.h. Even better, we should *embed* the static k= ey >> > in this structure. This will reduce the clutter and we wouldn't have to >> > deal with all the section stuff (the hyp_data thing is a good cleanup, >> > but I'd like to see it as a separate patch if possible). > Yes, it is what I was thinking about too, but was not sure about which > way to go, so hyp_data seemed me something we might reuse latter. > However, I agree that we can defer hyp_data thing... > = I've just tried it out and it seems that static keys are not happy to accept a key after kern_hyp_va is applied at &kvm_vgic_global_state: > In file included from ./include/linux/jump_label.h:105:0, > from arch/arm64/kvm/hyp/switch.c:19: > ./arch/arm64/include/asm/jump_label.h: In function =91__guest_run=92: > ./arch/arm64/include/asm/jump_label.h:31:2: warning: asm operand 0 probab= ly doesn=92t match constraints > asm goto("1: nop\n\t" > ^ > ./arch/arm64/include/asm/jump_label.h:31:2: warning: asm operand 0 probab= ly doesn=92t match constraints > asm goto("1: nop\n\t" > ^ > ./arch/arm64/include/asm/jump_label.h:31:2: error: impossible constraint = in =91asm=92 > asm goto("1: nop\n\t" > ^ > ./arch/arm64/include/asm/jump_label.h:31:2: error: impossible constraint = in =91asm=92 > asm goto("1: nop\n\t" > ^ > make[1]: *** [arch/arm64/kvm/hyp/switch.o] Error 1 > make: *** [arch/arm64/kvm/hyp/switch.o] Error 2 it looks like we cannot avoid hyp_data thing... if you don't mind I can do hyp_data clean-up in separate patch. Alternatively, we can do conversion to static keys for both architectures later as an optimisation step. Cheers Vladimir