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 17:18:14 +0100 Message-ID: <57D2E0C6.1040608@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> <57D2BCEB.3030306@arm.com> <57D2C469.1030006@arm.com> <57D2D1F0.301@arm.com> <57D2D486.3090100@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 11AD4410EB for ; Fri, 9 Sep 2016 12:09:46 -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 vV1uW9IaNJew for ; Fri, 9 Sep 2016 12:09:44 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B3A6940FA2 for ; Fri, 9 Sep 2016 12:09:44 -0400 (EDT) In-Reply-To: <57D2D486.3090100@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 16:25, Marc Zyngier wrote: > On 09/09/16 16:14, Vladimir Murzin wrote: >> On 09/09/16 15:17, Marc Zyngier wrote: >>> On 09/09/16 14:45, Vladimir Murzin wrote: >>>> 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, wh= ich >>>>>>> is declared in arm_vgic.h. Even better, we should *embed* the stati= c key >>>>>>> in this structure. This will reduce the clutter and we wouldn't hav= e to >>>>>>> deal with all the section stuff (the hyp_data thing is a good clean= up, >>>>>>> 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: >>> >>> Ah, there is a trick. You do not need kern_hyp_va at all, because this >>> is not evaluated as an expression at runtime (so the pointer doesn't ma= tter). >>> >> >> Ah, right, thank for a tip! ;) >> >>>>> 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 pr= obably doesn=92t match constraints >>>>> asm goto("1: nop\n\t" >>>>> ^ >>>>> ./arch/arm64/include/asm/jump_label.h:31:2: warning: asm operand 0 pr= obably doesn=92t match constraints >>>>> asm goto("1: nop\n\t" >>>>> ^ >>>>> ./arch/arm64/include/asm/jump_label.h:31:2: error: impossible constra= int in =91asm=92 >>>>> asm goto("1: nop\n\t" >>>>> ^ >>>>> ./arch/arm64/include/asm/jump_label.h:31:2: error: impossible constra= int 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. >>> >>> Can you try the above first? I've just tried the same approach with my >>> vgic-trap series, and it compiles fine (untested though): >> >> I was about to try it out, but didn't manage to find a branch with >> vgic-trap series, so I did a quick fixup for my series and now it is >> running non-VHE boot tests and I don't expect issues with VHE one. I >> think diff bellow should work runtime too, but if you do want me to give >> it a try it'd be handy to have a branch I can pull from ;) > = > I think Christoffer has pulled it into kvmarm/queue. Nothing has exploded so far for both architectures. Cheers Vladimir