From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH v3 1/8] arm64: KVM: Use static keys for selecting the GIC backend Date: Fri, 9 Sep 2016 15:17:13 +0100 Message-ID: <57D2C469.1030006@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> 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 C91354113E for ; Fri, 9 Sep 2016 10:08:45 -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 eIQWK0I9n6Zo for ; Fri, 9 Sep 2016 10:08:45 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D643F40F9B for ; Fri, 9 Sep 2016 10:08:43 -0400 (EDT) In-Reply-To: <57D2BCEB.3030306@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: Vladimir Murzin , 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 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, 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: 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 matter= ). >> 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 proba= bly doesn=92t match constraints >> asm goto("1: nop\n\t" >> ^ >> ./arch/arm64/include/asm/jump_label.h:31:2: warning: asm operand 0 proba= bly 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. Can you try the above first? I've just tried the same approach with my vgic-trap series, and it compiles fine (untested though): diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 194184c..397e240 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -301,7 +301,7 @@ again: if (exit_code =3D=3D ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu)) goto again; = - if (static_branch_unlikely(&vgic_v2_cpuif_trap) && + if (static_branch_unlikely(&kvm_vgic_global_state.vgic_v2_cpuif_trap) && exit_code =3D=3D ARM_EXCEPTION_TRAP) { bool valid; = diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index bb46c03..cc59a28 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -67,6 +67,9 @@ struct vgic_global { = /* Only needed for the legacy KVM_CREATE_IRQCHIP */ bool can_emulate_gicv2; + + /* Trapping GICv2 GICV region? */ + struct static_key_false vgic_v2_cpuif_trap; }; = extern struct vgic_global kvm_vgic_global_state; @@ -269,8 +272,6 @@ struct vgic_cpu { bool lpis_enabled; }; = -extern struct static_key_false vgic_v2_cpuif_trap; - int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool wri= te); void kvm_vgic_early_init(struct kvm *kvm); int kvm_vgic_create(struct kvm *kvm, u32 type); diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c index 0a063af..4af600e 100644 --- a/virt/kvm/arm/vgic/vgic-v2.c +++ b/virt/kvm/arm/vgic/vgic-v2.c @@ -278,7 +278,7 @@ int vgic_v2_map_resources(struct kvm *kvm) goto out; } = - if (!static_branch_unlikely(&vgic_v2_cpuif_trap)) { + if (!static_branch_unlikely(&kvm_vgic_global_state.vgic_v2_cpuif_trap)) { ret =3D kvm_phys_addr_ioremap(kvm, dist->vgic_cpu_base, kvm_vgic_global_state.vcpu_base, KVM_VGIC_V2_CPU_SIZE, true); @@ -296,8 +296,6 @@ out: return ret; } = -DEFINE_STATIC_KEY_FALSE(vgic_v2_cpuif_trap); - /** * vgic_v2_probe - probe for a GICv2 compatible interrupt controller in DT * @node: pointer to the DT node @@ -314,6 +312,8 @@ int vgic_v2_probe(const struct gic_kvm_info *info) return -ENXIO; } = + kvm_vgic_global_state.vgic_v2_cpuif_trap =3D STATIC_KEY_FALSE_INIT; + if (!PAGE_ALIGNED(info->vcpu.start) || !PAGE_ALIGNED(resource_size(&info->vcpu))) { kvm_info("GICV region size/alignment is unsafe, using trapping (reduced = performance)\n"); @@ -332,7 +332,7 @@ int vgic_v2_probe(const struct gic_kvm_info *info) goto out; } = - static_branch_enable(&vgic_v2_cpuif_trap); + static_branch_enable(&kvm_vgic_global_state.vgic_v2_cpuif_trap); } = kvm_vgic_global_state.vctrl_base =3D ioremap(info->vctrl.start, Thanks, M. -- = Jazz is not dead. It just smells funny...