From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A370C433E0 for ; Thu, 18 Jun 2020 16:34:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A8E82080D for ; Thu, 18 Jun 2020 16:34:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592498085; bh=eVyEMYcH3w0tu/t9tmx43Zd823558bcJbUdQrBCBp4c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=dqQr3MHiMP7PBSckvyZY2GzXJLidVISVH0kSNonAYlkTWLLHBnFrJ61mGy6+iQOWf yU4qCz/RVaAND9GTUehfL/9Vit+ztYdKScwtr4hJbku0QpBK1FExYN4ZFVxgtxFUco 4fM8Jlozudw6Vj0/ibXwU71+Ee3OiF1VQG/mi9Z0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728629AbgFRQen (ORCPT ); Thu, 18 Jun 2020 12:34:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:46846 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727114AbgFRQem (ORCPT ); Thu, 18 Jun 2020 12:34:42 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F3A5F2080D; Thu, 18 Jun 2020 16:34:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592498082; bh=eVyEMYcH3w0tu/t9tmx43Zd823558bcJbUdQrBCBp4c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HvgtGquIIepvj2gQkKFmCpbCeAgAeeIo7rCFhFWj26c+6IajL8BvAWaMt/UCkLjBj Vtdzg6b/vnsNPFtyukEyPsuxiiDQ5nOPcGjyj1C4NTiv/RWhz9FGbzBk2HXK3F60XQ aftQCISswXvKXTI+OuS8zmbSzVxSrPM211c2bCl0= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jlxUu-004EIo-A4; Thu, 18 Jun 2020 17:34:40 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 18 Jun 2020 17:34:40 +0100 From: Marc Zyngier To: David Brazdil Cc: Will Deacon , Catalin Marinas , James Morse , Julien Thierry , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, kernel-team@android.com Subject: Re: [PATCH v3 03/15] arm64: kvm: Add build rules for separate nVHE object files In-Reply-To: <20200618122537.9625-4-dbrazdil@google.com> References: <20200618122537.9625-1-dbrazdil@google.com> <20200618122537.9625-4-dbrazdil@google.com> User-Agent: Roundcube Webmail/1.4.5 Message-ID: <09976ea31931481f4e00d627dc5e06fe@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: dbrazdil@google.com, will@kernel.org, catalin.marinas@arm.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi David, On 2020-06-18 13:25, David Brazdil wrote: > Add new folder arch/arm64/kvm/hyp/nvhe and a Makefile for building code > that > runs in EL2 under nVHE KVM. > > Compile each source file into a `.hyp.tmp.o` object first, then prefix > all > its symbols with "__kvm_nvhe_" using `objcopy` and produce a `.hyp.o`. > Suffixes were chosen so that it would be possible for VHE and nVHE to > share > some source files, but compiled with different CFLAGS. nVHE build rules > add > -D__KVM_NVHE_HYPERVISOR__. > > The nVHE ELF symbol prefix is added to kallsyms.c as ignored. EL2-only > symbols > will never appear in EL1 stack traces. > > Signed-off-by: David Brazdil > --- > arch/arm64/kernel/image-vars.h | 12 +++++++++++ > arch/arm64/kvm/hyp/Makefile | 2 +- > arch/arm64/kvm/hyp/nvhe/Makefile | 35 ++++++++++++++++++++++++++++++++ > scripts/kallsyms.c | 1 + > 4 files changed, 49 insertions(+), 1 deletion(-) > create mode 100644 arch/arm64/kvm/hyp/nvhe/Makefile > > diff --git a/arch/arm64/kernel/image-vars.h > b/arch/arm64/kernel/image-vars.h > index be0a63ffed23..f32b406e90c0 100644 > --- a/arch/arm64/kernel/image-vars.h > +++ b/arch/arm64/kernel/image-vars.h > @@ -51,4 +51,16 @@ __efistub__ctype = _ctype; > > #endif > > +#ifdef CONFIG_KVM > + > +/* > + * KVM nVHE code has its own symbol namespace prefixed by __kvm_nvhe_, > to > + * isolate it from the kernel proper. The following symbols are > legally > + * accessed by it, therefore provide aliases to make them linkable. > + * Do not include symbols which may not be safely accessed under > hypervisor > + * memory mappings. > + */ > + > +#endif /* CONFIG_KVM */ > + > #endif /* __ARM64_KERNEL_IMAGE_VARS_H */ > diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile > index 5d8357ddc234..5f4f217532e0 100644 > --- a/arch/arm64/kvm/hyp/Makefile > +++ b/arch/arm64/kvm/hyp/Makefile > @@ -6,7 +6,7 @@ > ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \ > $(DISABLE_STACKLEAK_PLUGIN) > > -obj-$(CONFIG_KVM) += hyp.o > +obj-$(CONFIG_KVM) += hyp.o nvhe/ > obj-$(CONFIG_KVM_INDIRECT_VECTORS) += smccc_wa.o > > hyp-y := vgic-v3-sr.o timer-sr.o aarch32.o vgic-v2-cpuif-proxy.o > sysreg-sr.o \ > diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile > b/arch/arm64/kvm/hyp/nvhe/Makefile > new file mode 100644 > index 000000000000..7d64235dba62 > --- /dev/null > +++ b/arch/arm64/kvm/hyp/nvhe/Makefile > @@ -0,0 +1,35 @@ > +# SPDX-License-Identifier: GPL-2.0 > +# > +# Makefile for Kernel-based Virtual Machine module, HYP/nVHE part > +# > + > +asflags-y := -D__KVM_NVHE_HYPERVISOR__ > +ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -fno-stack-protector \ > + -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN) > + > +obj-y := > + > +obj-y := $(patsubst %.o,%.hyp.o,$(obj-y)) > +extra-y := $(patsubst %.hyp.o,%.hyp.tmp.o,$(obj-y)) > + > +$(obj)/%.hyp.tmp.o: $(src)/%.c FORCE > + $(call if_changed_rule,cc_o_c) > +$(obj)/%.hyp.tmp.o: $(src)/%.S FORCE > + $(call if_changed_rule,as_o_S) > +$(obj)/%.hyp.o: $(obj)/%.hyp.tmp.o FORCE > + $(call if_changed,hypcopy) > + > +quiet_cmd_hypcopy = HYPCOPY $@ > + cmd_hypcopy = $(OBJCOPY) --prefix-symbols=__kvm_nvhe_ $< $@ > + > +# KVM nVHE code is run at a different exception code with a different > map, so > +# compiler instrumentation that inserts callbacks or checks into the > code may > +# cause crashes. Just disable it. > +GCOV_PROFILE := n > +KASAN_SANITIZE := n > +UBSAN_SANITIZE := n > +KCOV_INSTRUMENT := n > + > +# Skip objtool checking for this directory because nVHE code is > compiled with > +# non-standard build rules. > +OBJECT_FILES_NON_STANDARD := y > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c > index 6dc3078649fa..0096cd965332 100644 > --- a/scripts/kallsyms.c > +++ b/scripts/kallsyms.c > @@ -109,6 +109,7 @@ static bool is_ignored_symbol(const char *name, > char type) > ".LASANPC", /* s390 kasan local symbols */ > "__crc_", /* modversions */ > "__efistub_", /* arm64 EFI stub namespace */ > + "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */ > NULL > }; I guess that one of the first use of this __KVM_NVHE_HYPERVISOR__ flag could be the has_vhe() predicate: if you're running the nVHE code, you are *guaranteed* not to use VHE at all. Something like: diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index 5051b388c654..b2cb8fce43dd 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -85,10 +85,8 @@ static inline bool is_kernel_in_hyp_mode(void) static __always_inline bool has_vhe(void) { - if (cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN)) - return true; - - return false; + return (__is_defined(__KVM_NVHE_HYPERVISOR__) && + cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN)); } #endif /* __ASSEMBLY__ */ Thanks, M. -- Jazz is not dead. It just smells funny...