From: Mark Rutland <mark.rutland@arm.com> To: Marc Zyngier <marc.zyngier@arm.com> Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Christoffer Dall <christoffer.dall@linaro.org>, Eric Auger <eric.auger@redhat.com>, Shanker Donthineni <shankerd@codeaurora.org>, Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>, Andre Przywara <Andre.Przywara@arm.com> Subject: Re: [PATCH v4 25/26] KVM: arm/arm64: GICv4: Prevent heterogenous systems from using GICv4 Date: Fri, 27 Oct 2017 08:37:28 +0100 [thread overview] Message-ID: <20171027073728.taejncafoehkfzuc@salmiak> (raw) In-Reply-To: <868tfxaxiv.fsf@arm.com> On Fri, Oct 27, 2017 at 07:57:12AM +0100, Marc Zyngier wrote: > On Thu, Oct 26 2017 at 4:48:39 pm BST, Mark Rutland <mark.rutland@arm.com> wrote: > > On Fri, Oct 06, 2017 at 04:34:00PM +0100, Marc Zyngier wrote: > >> @@ -485,8 +495,21 @@ int vgic_v3_probe(const struct gic_kvm_info *info) > >> kvm_vgic_global_state.can_emulate_gicv2 = false; > >> kvm_vgic_global_state.ich_vtr_el2 = ich_vtr_el2; > >> > >> - /* GICv4 support? */ > >> + /* > >> + * GICv4 support? We need to check on all CPUs in case of some > >> + * extremely creative form of big-little brain damage... > >> + */ > >> if (info->has_v4) { > >> + int cpu; > >> + > >> + for_each_online_cpu(cpu) { > >> + bool enable; > >> + > >> + smp_call_function_single(cpu, vgic_check_v4_cpuif, > >> + &enable, 1); > >> + gicv4_enable = gicv4_enable && enable; > >> + } > > > > With maxcpus=N on the command line, CPUs can be brought online late, so we > > might need this in a hotplug callback (and/or in the arm64 cpufeature > > framework) to handle that case. > > I'm afraid that won't be enough. If the CPU is brought up once we've > already started a VM, we're screwed, as we cannot retroactively decide > to drop GICv4 on the floor and nuke the guest. Or did you have something > more radical in mind? Panic? If you teach the arm64 cpufeature framework about this, it can abort bringing a !GICv4 CPU online late. It already handles onlining a !FP CPU if all boot CPUs had FP, for example. See verify_local_cpu_features() in arch/arm64/kernel/cpufeature.c. Thanks, Mark.
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From: mark.rutland@arm.com (Mark Rutland) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 25/26] KVM: arm/arm64: GICv4: Prevent heterogenous systems from using GICv4 Date: Fri, 27 Oct 2017 08:37:28 +0100 [thread overview] Message-ID: <20171027073728.taejncafoehkfzuc@salmiak> (raw) In-Reply-To: <868tfxaxiv.fsf@arm.com> On Fri, Oct 27, 2017 at 07:57:12AM +0100, Marc Zyngier wrote: > On Thu, Oct 26 2017 at 4:48:39 pm BST, Mark Rutland <mark.rutland@arm.com> wrote: > > On Fri, Oct 06, 2017 at 04:34:00PM +0100, Marc Zyngier wrote: > >> @@ -485,8 +495,21 @@ int vgic_v3_probe(const struct gic_kvm_info *info) > >> kvm_vgic_global_state.can_emulate_gicv2 = false; > >> kvm_vgic_global_state.ich_vtr_el2 = ich_vtr_el2; > >> > >> - /* GICv4 support? */ > >> + /* > >> + * GICv4 support? We need to check on all CPUs in case of some > >> + * extremely creative form of big-little brain damage... > >> + */ > >> if (info->has_v4) { > >> + int cpu; > >> + > >> + for_each_online_cpu(cpu) { > >> + bool enable; > >> + > >> + smp_call_function_single(cpu, vgic_check_v4_cpuif, > >> + &enable, 1); > >> + gicv4_enable = gicv4_enable && enable; > >> + } > > > > With maxcpus=N on the command line, CPUs can be brought online late, so we > > might need this in a hotplug callback (and/or in the arm64 cpufeature > > framework) to handle that case. > > I'm afraid that won't be enough. If the CPU is brought up once we've > already started a VM, we're screwed, as we cannot retroactively decide > to drop GICv4 on the floor and nuke the guest. Or did you have something > more radical in mind? Panic? If you teach the arm64 cpufeature framework about this, it can abort bringing a !GICv4 CPU online late. It already handles onlining a !FP CPU if all boot CPUs had FP, for example. See verify_local_cpu_features() in arch/arm64/kernel/cpufeature.c. Thanks, Mark.
next prev parent reply other threads:[~2017-10-27 7:37 UTC|newest] Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-10-06 15:33 [PATCH v4 00/26] KVM/ARM: Add support for GICv4 Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 01/26] KVM: arm/arm64: register irq bypass consumer on ARM/ARM64 Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 02/26] KVM: arm/arm64: vgic: restructure kvm_vgic_(un)map_phys_irq Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 14:44 ` Christoffer Dall 2017-10-25 14:44 ` Christoffer Dall 2017-10-26 13:05 ` Marc Zyngier 2017-10-26 13:05 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 03/26] KVM: arm: Select ARM_GIC_V3 and ARM_GIC_V3_ITS Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 04/26] KVM: arm/arm64: vgic: Move kvm_vgic_destroy call around Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 05/26] KVM: arm/arm64: vITS: Add MSI translation helpers Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 06/26] KVM: arm/arm64: vITS: Add a helper to update the affinity of an LPI Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 14:50 ` Christoffer Dall 2017-10-25 14:50 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 07/26] KVM: arm/arm64: GICv4: Add property field and per-VM predicate Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 14:54 ` Christoffer Dall 2017-10-25 14:54 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 08/26] KVM: arm/arm64: GICv4: Add init/teardown of the per-VM vPE irq domain Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 15:46 ` Christoffer Dall 2017-10-25 15:46 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 09/26] KVM: arm/arm64: GICv4: Wire mapping/unmapping of VLPIs in VFIO irq bypass Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 15:58 ` Christoffer Dall 2017-10-25 15:58 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 10/26] KVM: arm/arm64: GICv4: Handle INT command applied to a VLPI Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 11/26] KVM: arm/arm64: GICv4: Unmap VLPI when freeing an LPI Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 12/26] KVM: arm/arm64: GICv4: Propagate affinity changes to the physical ITS Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 16:22 ` Christoffer Dall 2017-10-25 16:22 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 13/26] KVM: arm/arm64: GICv4: Handle CLEAR applied to a VLPI Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 14/26] KVM: arm/arm64: GICv4: Handle MOVALL applied to a vPE Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 16:27 ` Christoffer Dall 2017-10-25 16:27 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 15/26] KVM: arm/arm64: GICv4: Propagate property updates to VLPIs Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 16/26] KVM: arm/arm64: GICv4: Handle INVALL applied to a vPE Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 17/26] KVM: arm/arm64: GICv4: Propagate VLPI properties at map time Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-25 16:48 ` Christoffer Dall 2017-10-25 16:48 ` Christoffer Dall 2017-10-25 17:01 ` Marc Zyngier 2017-10-25 17:01 ` Marc Zyngier 2017-10-26 8:21 ` Marc Zyngier 2017-10-26 8:21 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 18/26] KVM: arm/arm64: GICv4: Use pending_last as a scheduling hint Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 19/26] KVM: arm/arm64: GICv4: Add doorbell interrupt handling Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-26 14:28 ` Christoffer Dall 2017-10-26 14:28 ` Christoffer Dall 2017-10-26 15:25 ` Christoffer Dall 2017-10-26 15:25 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 20/26] KVM: arm/arm64: GICv4: Use the doorbell interrupt as an unblocking source Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 21/26] KVM: arm/arm64: GICv4: Hook vPE scheduling into vgic flush/sync Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-26 15:24 ` Christoffer Dall 2017-10-26 15:24 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 22/26] KVM: arm/arm64: GICv4: Enable virtual cpuif if VLPIs can be delivered Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:33 ` [PATCH v4 23/26] KVM: arm/arm64: GICv4: Prevent a VM using GICv4 from being saved Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-26 15:28 ` Christoffer Dall 2017-10-26 15:28 ` Christoffer Dall 2017-10-27 13:56 ` Marc Zyngier 2017-10-27 13:56 ` Marc Zyngier 2017-10-30 6:48 ` Christoffer Dall 2017-10-30 6:48 ` Christoffer Dall 2017-10-06 15:33 ` [PATCH v4 24/26] KVM: arm/arm64: GICv4: Enable VLPI support Marc Zyngier 2017-10-06 15:33 ` Marc Zyngier 2017-10-06 15:34 ` [PATCH v4 25/26] KVM: arm/arm64: GICv4: Prevent heterogenous systems from using GICv4 Marc Zyngier 2017-10-06 15:34 ` Marc Zyngier 2017-10-26 15:31 ` Christoffer Dall 2017-10-26 15:31 ` Christoffer Dall 2017-10-26 15:48 ` Mark Rutland 2017-10-26 15:48 ` Mark Rutland 2017-10-27 6:57 ` Marc Zyngier 2017-10-27 6:57 ` Marc Zyngier 2017-10-27 6:57 ` Marc Zyngier 2017-10-27 7:37 ` Mark Rutland [this message] 2017-10-27 7:37 ` Mark Rutland 2017-10-27 7:59 ` Marc Zyngier 2017-10-27 7:59 ` Marc Zyngier 2017-10-27 7:59 ` Marc Zyngier 2017-10-27 8:04 ` Mark Rutland 2017-10-27 8:04 ` Mark Rutland 2017-10-27 8:31 ` Marc Zyngier 2017-10-27 8:31 ` Marc Zyngier 2017-10-27 8:31 ` Marc Zyngier 2017-10-29 2:16 ` Christoffer Dall 2017-10-29 2:16 ` Christoffer Dall 2017-10-06 15:34 ` [PATCH v4 26/26] KVM: arm/arm64: GICv4: Theory of operations Marc Zyngier 2017-10-06 15:34 ` Marc Zyngier 2017-10-26 15:32 ` Christoffer Dall 2017-10-26 15:32 ` Christoffer Dall 2017-10-08 16:45 ` [PATCH v4 00/26] KVM/ARM: Add support for GICv4 Shanker Donthineni 2017-10-08 16:45 ` Shanker Donthineni 2017-10-09 17:52 ` Konrad Rzeszutek Wilk 2017-10-09 17:52 ` Konrad Rzeszutek Wilk 2017-10-09 18:02 ` Marc Zyngier 2017-10-09 18:02 ` Marc Zyngier 2017-10-19 15:48 ` [PATCH v4 27/26] KVM: arm/arm64: GICv4: Prevent userspace from changing doorbell affinity Marc Zyngier 2017-10-19 15:48 ` Marc Zyngier
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