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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 4903CC433E2 for ; Mon, 25 May 2020 15:15:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2260020723 for ; Mon, 25 May 2020 15:15:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="kOFxbK1S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391108AbgEYPP2 (ORCPT ); Mon, 25 May 2020 11:15:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390911AbgEYPP1 (ORCPT ); Mon, 25 May 2020 11:15:27 -0400 Received: from mail-lf1-x141.google.com (mail-lf1-x141.google.com [IPv6:2a00:1450:4864:20::141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA94BC061A0E for ; Mon, 25 May 2020 08:15:26 -0700 (PDT) Received: by mail-lf1-x141.google.com with SMTP id u16so8924594lfl.8 for ; Mon, 25 May 2020 08:15:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=kYBoEhN96Rd2bTOOCtpwhH5a3zXfbXb8vg+QY2lOxCg=; b=kOFxbK1SPD4S5SY6soHeM+HeZetfnuSzhji+qxwHWT0CnYGiTqbZyd5Pheqma0e875 +MeqLFtQktc2cDAhBp28exGqp9SwAbHfgwh33X7Te8RypMFK9HWnQkL2MrzsNAqCScK6 JNLnQru0CXvZL1fQ60ltcd37sXmyjoIIwuA3QVgq6EEAGQFDP28U90KbysSCsAeJrZU+ l4sNaJTOLAogUGRzOYArKj/L5yRHfKyz6aiMa9ry//yHODMO8hQzJ+4yZO8KA70LH7Du MKZy5UHT00e34txu1vJGIP8KP5A9zj1TgpxR4Y3ffECpWvGwe+FB9ovaeS2dyXSdWvZK Ptqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=kYBoEhN96Rd2bTOOCtpwhH5a3zXfbXb8vg+QY2lOxCg=; b=eGJ3K7HMsDF8Yq1FfDo2j2vEfHiJJUEJbJzUh/FoY5s+x/8qPqAWI27BSOuoemCjbm TeQhkHpdO3TuAtumfVpuJ5I2PCg1hF9jIuIbp4NL/HCVhTv3G+8TWhL3L/414y21JWxx hlg4LtIFe9ewtF0A+VNmzOCxQruQAuY9XJ98BLrtqz0AmuVSBjiLoY7brcXjJNUw4Lzs 9PBJI+7JKM8zfO6T5x7cRWzuDIeQuKJJgDKkJ9XmZgNYXy9rJ0tqI3kOsJnm3otBMDun Ctt9BsNTBH5WbaQD+LjOyhDsw3eqtNj9HpypNUMk8k7PRccK1IxgaVajDeIYoq265pDd FlzQ== X-Gm-Message-State: AOAM532NwZn0IiO2xts1LwekYOf3tRvZ/Ts6AHhMuRGfB5cWGmvkPPyY BWpMAX0QF0Yv5bK6CC0Ekift7A== X-Google-Smtp-Source: ABdhPJzXLUWIYgQQ8mQTCK0ROPNDbamXhbZpVXtVtJCcCUP29y0cVktOsqQ6gbXEx34Ez3amGKFUwA== X-Received: by 2002:a19:c505:: with SMTP id w5mr2287001lfe.201.1590419725196; Mon, 25 May 2020 08:15:25 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id f6sm4673999ljn.91.2020.05.25.08.15.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2020 08:15:24 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 79D1410230F; Mon, 25 May 2020 18:15:25 +0300 (+03) Date: Mon, 25 May 2020 18:15:25 +0300 From: "Kirill A. Shutemov" To: Vitaly Kuznetsov Cc: David Rientjes , Andrea Arcangeli , Kees Cook , Will Drewry , "Edgecombe, Rick P" , "Kleen, Andi" , x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Paolo Bonzini , Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel Subject: Re: [RFC 02/16] x86/kvm: Introduce KVM memory protection feature Message-ID: <20200525151525.qmfvzxbl7sq46cdq@box> References: <20200522125214.31348-1-kirill.shutemov@linux.intel.com> <20200522125214.31348-3-kirill.shutemov@linux.intel.com> <87d06s83is.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87d06s83is.fsf@vitty.brq.redhat.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 25, 2020 at 04:58:51PM +0200, Vitaly Kuznetsov wrote: > "Kirill A. Shutemov" writes: > > > Provide basic helpers, KVM_FEATURE and a hypercall. > > > > Host side doesn't provide the feature yet, so it is a dead code for now. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > arch/x86/include/asm/kvm_para.h | 5 +++++ > > arch/x86/include/uapi/asm/kvm_para.h | 3 ++- > > arch/x86/kernel/kvm.c | 16 ++++++++++++++++ > > include/uapi/linux/kvm_para.h | 3 ++- > > 4 files changed, 25 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h > > index 9b4df6eaa11a..3ce84fc07144 100644 > > --- a/arch/x86/include/asm/kvm_para.h > > +++ b/arch/x86/include/asm/kvm_para.h > > @@ -10,11 +10,16 @@ extern void kvmclock_init(void); > > > > #ifdef CONFIG_KVM_GUEST > > bool kvm_check_and_clear_guest_paused(void); > > +bool kvm_mem_protected(void); > > #else > > static inline bool kvm_check_and_clear_guest_paused(void) > > { > > return false; > > } > > +static inline bool kvm_mem_protected(void) > > +{ > > + return false; > > +} > > #endif /* CONFIG_KVM_GUEST */ > > > > #define KVM_HYPERCALL \ > > diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h > > index 2a8e0b6b9805..c3b499acc98f 100644 > > --- a/arch/x86/include/uapi/asm/kvm_para.h > > +++ b/arch/x86/include/uapi/asm/kvm_para.h > > @@ -28,9 +28,10 @@ > > #define KVM_FEATURE_PV_UNHALT 7 > > #define KVM_FEATURE_PV_TLB_FLUSH 9 > > #define KVM_FEATURE_ASYNC_PF_VMEXIT 10 > > -#define KVM_FEATURE_PV_SEND_IPI 11 > > +#define KVM_FEATURE_PV_SEND_IPI 11 > > Nit: spurrious change > I fixed indentation while there. (Look at the file, not the diff to see what I mean). > > #define KVM_FEATURE_POLL_CONTROL 12 > > #define KVM_FEATURE_PV_SCHED_YIELD 13 > > +#define KVM_FEATURE_MEM_PROTECTED 14 > > > > #define KVM_HINTS_REALTIME 0 > > > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > > index 6efe0410fb72..bda761ca0d26 100644 > > --- a/arch/x86/kernel/kvm.c > > +++ b/arch/x86/kernel/kvm.c > > @@ -35,6 +35,13 @@ > > #include > > #include > > > > +static bool mem_protected; > > + > > +bool kvm_mem_protected(void) > > +{ > > + return mem_protected; > > +} > > + > > Honestly, I don't see a need for kvm_mem_protected(), just rename the > bool if you need kvm_ prefix :-) For !CONFIG_KVM_GUEST it would not be a variable. We may want to change it to static branch or something in the future. > > static int kvmapf = 1; > > > > static int __init parse_no_kvmapf(char *arg) > > @@ -727,6 +734,15 @@ static void __init kvm_init_platform(void) > > { > > kvmclock_init(); > > x86_platform.apic_post_init = kvm_apic_init; > > + > > + if (kvm_para_has_feature(KVM_FEATURE_MEM_PROTECTED)) { > > + if (kvm_hypercall0(KVM_HC_ENABLE_MEM_PROTECTED)) { > > + pr_err("Failed to enable KVM memory protection\n"); > > + return; > > + } > > + > > + mem_protected = true; > > + } > > } > > Personally, I'd prefer to do this via setting a bit in a KVM-specific > MSR instead. The benefit is that the guest doesn't need to remember if > it enabled the feature or not, it can always read the config msr. May > come handy for e.g. kexec/kdump. I think we would need to remember it anyway. Accessing MSR is somewhat expensive. But, okay, I can rework it MSR if needed. Note, that we can avoid the enabling algother, if we modify BIOS to deal with private/shared memory. Currently BIOS get system crash if we enable the feature from time zero. > > const __initconst struct hypervisor_x86 x86_hyper_kvm = { > > diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h > > index 8b86609849b9..1a216f32e572 100644 > > --- a/include/uapi/linux/kvm_para.h > > +++ b/include/uapi/linux/kvm_para.h > > @@ -27,8 +27,9 @@ > > #define KVM_HC_MIPS_EXIT_VM 7 > > #define KVM_HC_MIPS_CONSOLE_OUTPUT 8 > > #define KVM_HC_CLOCK_PAIRING 9 > > -#define KVM_HC_SEND_IPI 10 > > +#define KVM_HC_SEND_IPI 10 > > Same spurrious change detected. The same justification :) > > #define KVM_HC_SCHED_YIELD 11 > > +#define KVM_HC_ENABLE_MEM_PROTECTED 12 > > > > /* > > * hypercalls use architecture specific > > -- > Vitaly > > -- Kirill A. Shutemov