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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 366ECEB64D7 for ; Wed, 28 Jun 2023 23:01:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230173AbjF1XBD (ORCPT ); Wed, 28 Jun 2023 19:01:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231464AbjF1XA7 (ORCPT ); Wed, 28 Jun 2023 19:00:59 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30456172D for ; Wed, 28 Jun 2023 16:00:58 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-bd6df68105cso39072276.2 for ; Wed, 28 Jun 2023 16:00:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1687993257; x=1690585257; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=8gb2MF1v1Rq3zxlmhOpRBTFk6nl/PtNFob1fT2upCoM=; b=SkxwSILpqMQiHM5Vz80792QoVEN7jJrfnEi24dfSL0u0c4JaFZvju7B7bvbSIZyCTB 4RgLk4fWY5C5KV7EYxXd1zZSxdTkSMKtAmeA/IXTNKk4m4i2k08HMAOyj0HOwc576CLS /1XWCzO7Z4G+iSNkAQjkXhAr0zi2/Rj4ull0hiluNsTmyeUtfVoEj/2Ient24xztcchb ag3RlDV6odx6HOenzEBQ8p7LOCqLx9MsRnkUbWuC591IOLjjzvjd9c7PChjGPuGtVM0l yTH6tIcs7JSNptLkuy90ACOAH11NsaOdOFkiNRUTh940HiLqdZ138t8QroqvxRgt5iP4 cpRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687993257; x=1690585257; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=8gb2MF1v1Rq3zxlmhOpRBTFk6nl/PtNFob1fT2upCoM=; b=DxqYFjDeS1CSHtbsQC/SxcF1phf68iNWwW0xYepQLU8ngSwg/knWr7liIukciXVl6V HXltWSUbnPDsVVkVfQy9hMQYStnpKY7IYx/6TmQEiHdxHGSZUDGh5yVn92XjL3wPB3Zd HDpq5y0BwuQ+cFjp/JSQT3xp759GovjapLdLMkLEm4rhTnVrAtWGnGwqVQPvceUXajON u0UlUYmgOlDJwaWJ9CXC0kUd3DciA+GZIb14aYmuaw/XqnV7xoHYH1byjPHLJJaQLKvc iUYqHhHKfWCbo1cqKnsVS1+uwsrRFWwDu3gjzygCGtkS9g6bxQJBqPT2YGh4y3+yTxi7 xshA== X-Gm-Message-State: AC+VfDyUhJ9j/SEMUNmaeLo8mMqQWWHmeh/EdzhFsFrWXHA+D6mxxSWf f37yXh/366YL0ZFIv8tRndfbiEyt3dI= X-Google-Smtp-Source: ACHHUZ4v9Havux+Snzbh1IQI8dw2MyLszJ9oSfFYqWkJPutCtN/qeAmHysjqhzlg1N1d9V4AwuIac5T/eNw= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:42d5:0:b0:c10:8dd0:d942 with SMTP id p204-20020a2542d5000000b00c108dd0d942mr5534065yba.6.1687993257438; Wed, 28 Jun 2023 16:00:57 -0700 (PDT) Date: Wed, 28 Jun 2023 16:00:55 -0700 In-Reply-To: <20230616023945.7570-1-yan.y.zhao@intel.com> Mime-Version: 1.0 References: <20230616023101.7019-1-yan.y.zhao@intel.com> <20230616023945.7570-1-yan.y.zhao@intel.com> Message-ID: Subject: Re: [PATCH v3 09/11] KVM: x86/mmu: serialize vCPUs to zap gfn when guest MTRRs are honored From: Sean Christopherson To: Yan Zhao Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, chao.gao@intel.com, kai.huang@intel.com, robert.hoo.linux@gmail.com Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jun 16, 2023, Yan Zhao wrote: > diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c > index b35dd0bc9cad..688748e3a4d2 100644 > --- a/arch/x86/kvm/mtrr.c > +++ b/arch/x86/kvm/mtrr.c > @@ -25,6 +25,8 @@ > #define IA32_MTRR_DEF_TYPE_FE (1ULL << 10) > #define IA32_MTRR_DEF_TYPE_TYPE_MASK (0xff) > > +static void kvm_mtrr_zap_gfn_range(struct kvm_vcpu *vcpu, > + gfn_t gfn_start, gfn_t gfn_end); > static bool is_mtrr_base_msr(unsigned int msr) > { > /* MTRR base MSRs use even numbers, masks use odd numbers. */ > @@ -341,7 +343,7 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr) > var_mtrr_range(var_mtrr_msr_to_range(vcpu, msr), &start, &end); > } > > - kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end)); > + kvm_mtrr_zap_gfn_range(vcpu, gpa_to_gfn(start), gpa_to_gfn(end)); > } > > static bool var_mtrr_range_is_valid(struct kvm_mtrr_range *range) > @@ -437,6 +439,11 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) > void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu) > { > INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head); > + > + if (vcpu->vcpu_id == 0) { Eww. This is actually unsafe, because kvm_arch_vcpu_create() is invoked without holding kvm->lock. Oh, and vcpu_id is userspace controlled, so it's *very* unsafe. Just initialize these in kvm_arch_init_vm(). > + spin_lock_init(&vcpu->kvm->arch.mtrr_zap_list_lock); > + INIT_LIST_HEAD(&vcpu->kvm->arch.mtrr_zap_list); > + } > }