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[35.233.69.230]) by smtp.gmail.com with ESMTPSA id m22sm31890793wrh.66.2021.02.02.02.14.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Feb 2021 02:14:57 -0800 (PST) Date: Tue, 2 Feb 2021 10:14:51 +0000 From: Quentin Perret To: Will Deacon Cc: Catalin Marinas , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Rob Herring , Frank Rowand , devicetree@vger.kernel.org, android-kvm@google.com, linux-kernel@vger.kernel.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Fuad Tabba , Mark Rutland , David Brazdil Subject: Re: [RFC PATCH v2 11/26] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Message-ID: References: <20210108121524.656872-1-qperret@google.com> <20210108121524.656872-12-qperret@google.com> <20210201190620.GJ15632@willie-the-truck> <20210202100028.GA16657@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210202100028.GA16657@willie-the-truck> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 02 Feb 2021 at 10:00:29 (+0000), Will Deacon wrote: > On Tue, Feb 02, 2021 at 09:57:36AM +0000, Quentin Perret wrote: > > On Monday 01 Feb 2021 at 19:06:20 (+0000), Will Deacon wrote: > > > On Fri, Jan 08, 2021 at 12:15:09PM +0000, Quentin Perret wrote: > > > > In order to use the kernel list library at EL2, introduce stubs for the > > > > CONFIG_DEBUG_LIST out-of-lines calls. > > > > > > > > Signed-off-by: Quentin Perret > > > > --- > > > > arch/arm64/kvm/hyp/nvhe/Makefile | 2 +- > > > > arch/arm64/kvm/hyp/nvhe/stub.c | 22 ++++++++++++++++++++++ > > > > 2 files changed, 23 insertions(+), 1 deletion(-) > > > > create mode 100644 arch/arm64/kvm/hyp/nvhe/stub.c > > > > > > > > diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile > > > > index 1fc0684a7678..33bd381d8f73 100644 > > > > --- a/arch/arm64/kvm/hyp/nvhe/Makefile > > > > +++ b/arch/arm64/kvm/hyp/nvhe/Makefile > > > > @@ -10,7 +10,7 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o > > > > lib-objs := $(addprefix ../../../lib/, $(lib-objs)) > > > > > > > > obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \ > > > > - hyp-main.o hyp-smp.o psci-relay.o early_alloc.o > > > > + hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o > > > > obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \ > > > > ../fpsimd.o ../hyp-entry.o ../exception.o > > > > obj-y += $(lib-objs) > > > > diff --git a/arch/arm64/kvm/hyp/nvhe/stub.c b/arch/arm64/kvm/hyp/nvhe/stub.c > > > > new file mode 100644 > > > > index 000000000000..c0aa6bbfd79d > > > > --- /dev/null > > > > +++ b/arch/arm64/kvm/hyp/nvhe/stub.c > > > > @@ -0,0 +1,22 @@ > > > > +// SPDX-License-Identifier: GPL-2.0-only > > > > +/* > > > > + * Stubs for out-of-line function calls caused by re-using kernel > > > > + * infrastructure at EL2. > > > > + * > > > > + * Copyright (C) 2020 - Google LLC > > > > + */ > > > > + > > > > +#include > > > > + > > > > +#ifdef CONFIG_DEBUG_LIST > > > > +bool __list_add_valid(struct list_head *new, struct list_head *prev, > > > > + struct list_head *next) > > > > +{ > > > > + return true; > > > > +} > > > > + > > > > +bool __list_del_entry_valid(struct list_head *entry) > > > > +{ > > > > + return true; > > > > +} > > > > +#endif > > > > > > Can we get away with defining our own CHECK_DATA_CORRUPTION macro instead? > > > > Yes I think eventually it'd be nice to get there, but that has other > > implications (e.g. how do you report something in dmesg from EL2?) so > > perhaps we can keep that a separate series? > > We wouldn't necessarily have to report anything, but having the return value > of these functions be based off the generic checks would be great if we can > do it (i.e. we'd avoid corrupting the list). Ah, I see what you mean. Happy to have a go a it, there are a few other small things that make that it a bit annoying e.g. CHECK_DATA_CORRUPTION is unconditionally defined in bug.h, and I'll need to stub EXPORT_SYMBOL as well, which may both require changing core files, but maybe that's fine. And if that is too painful I think it would make sense to keep this a separate and self-contained series which would be a nice incremental improvement over the simple approach I have here :) Cheers, Quentin