From patchwork Fri Jun 16 02:32:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 13281967 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 15E1EEB64D9 for ; Fri, 16 Jun 2023 02:57:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239805AbjFPC5h (ORCPT ); Thu, 15 Jun 2023 22:57:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229509AbjFPC5f (ORCPT ); Thu, 15 Jun 2023 22:57:35 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C045297C; Thu, 15 Jun 2023 19:57:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1686884254; x=1718420254; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=ut2e3J98JDctUs6MMT7+OPH8GV0+N2ela+vuLlRy0YU=; b=VLl4mwSK3nWsjmnxllFM8zr+8D5U9sdl83C3d2ytVfcTFAy8qi/trJlf oJeHDf3OOglPkPuTuLhjiN1FbIYJUPIQc8EqZD1+QviozFeV7GyXvebjL Qiuqj6Us2NMCpHLy/+GhlQ1WJx6oyvpo8cDvVvZr3tYaORregT4xYPcvk W2RIjKFWznRK9BEl49GMasnurTqwn3TYAfocb1WlXzHtaS8mTvQsdHMgG ZdmaediC5yeLiw64QJhn/Es/qpN7sDurqJQQV3vf+njOIEJs1bOh++cb0 zuvaXMo6/5vE8xSD+BboIHqH9RYrYB91OXI4S8364Ild4p2/kFGO5/wTW A==; X-IronPort-AV: E=McAfee;i="6600,9927,10742"; a="387732923" X-IronPort-AV: E=Sophos;i="6.00,246,1681196400"; d="scan'208";a="387732923" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jun 2023 19:57:34 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10742"; a="802653734" X-IronPort-AV: E=Sophos;i="6.00,246,1681196400"; d="scan'208";a="802653734" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jun 2023 19:57:32 -0700 From: Yan Zhao To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: pbonzini@redhat.com, seanjc@google.com, chao.gao@intel.com, kai.huang@intel.com, robert.hoo.linux@gmail.com, Yan Zhao Subject: [PATCH v3 01/11] KVM: x86/mmu: helpers to return if KVM honors guest MTRRs Date: Fri, 16 Jun 2023 10:32:17 +0800 Message-Id: <20230616023217.7081-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230616023101.7019-1-yan.y.zhao@intel.com> References: <20230616023101.7019-1-yan.y.zhao@intel.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Added helpers to check if KVM honors guest MTRRs. The inner helper __kvm_mmu_honors_guest_mtrrs() is also provided to outside callers for the purpose of checking if guest MTRRs were honored before stopping non-coherent DMA. Suggested-by: Sean Christopherson Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu.h | 7 +++++++ arch/x86/kvm/mmu/mmu.c | 15 +++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 92d5a1924fc1..38bd449226f6 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -235,6 +235,13 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, return -(u32)fault & errcode; } +bool __kvm_mmu_honors_guest_mtrrs(struct kvm *kvm, bool vm_has_noncoherent_dma); + +static inline bool kvm_mmu_honors_guest_mtrrs(struct kvm *kvm) +{ + return __kvm_mmu_honors_guest_mtrrs(kvm, kvm_arch_has_noncoherent_dma(kvm)); +} + void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end); int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 1e5db621241f..b4f89f015c37 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4516,6 +4516,21 @@ static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, } #endif +bool __kvm_mmu_honors_guest_mtrrs(struct kvm *kvm, bool vm_has_noncoherent_dma) +{ + /* + * If the TDP is enabled, the host MTRRs are ignored by TDP + * (shadow_memtype_mask is non-zero), and the VM has non-coherent DMA + * (DMA doesn't snoop CPU caches), KVM's ABI is to honor the memtype + * from the guest's MTRRs so that guest accesses to memory that is + * DMA'd aren't cached against the guest's wishes. + * + * Note, KVM may still ultimately ignore guest MTRRs for certain PFNs, + * e.g. KVM will force UC memtype for host MMIO. + */ + return vm_has_noncoherent_dma && tdp_enabled && shadow_memtype_mask; +} + int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { /*