From patchwork Fri Jul 14 06:50:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 13313048 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 F2AA7EB64DA for ; Fri, 14 Jul 2023 07:17:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235238AbjGNHR6 (ORCPT ); Fri, 14 Jul 2023 03:17:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235221AbjGNHRu (ORCPT ); Fri, 14 Jul 2023 03:17:50 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9049126B3; Fri, 14 Jul 2023 00:17:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1689319069; x=1720855069; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=ut2e3J98JDctUs6MMT7+OPH8GV0+N2ela+vuLlRy0YU=; b=YndcM5mn3lBZKgh+LzVexAQHPVUIrMy0yPzV8Y+ZJ984DB1+ZbgWnBeK CJmgltDgKzDYgSqh7vXXh/2vur7DpnZA3rZsFV6VO4WQR2Qwg8rML8oNK xOTu9J9VDNyvXaGTbbwQzNFruaTeHhVnCJtqyjisbZOfzOeuqG9AVcNIh 3VzCy7MsIJo8aWdWbHXCymuc7Om3npoXKonmgPmkBx5jaMZl+Y2LcxAte RUJDi+Kfe0ACzHnNOOlHoK/irI/OmnJW406nvdj3eSue4dcPduv9wO4BD r5JlEVwBFDVreMms+9dPal+LmaF1BCcpd/tP7ImwTwqnvH3urOUiXbN+A Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10770"; a="396221566" X-IronPort-AV: E=Sophos;i="6.01,204,1684825200"; d="scan'208";a="396221566" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2023 00:16:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10770"; a="1052955616" X-IronPort-AV: E=Sophos;i="6.01,204,1684825200"; d="scan'208";a="1052955616" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2023 00:16:46 -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, yuan.yao@linux.intel.com, Yan Zhao Subject: [PATCH v4 01/12] KVM: x86/mmu: helpers to return if KVM honors guest MTRRs Date: Fri, 14 Jul 2023 14:50:06 +0800 Message-Id: <20230714065006.20201-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230714064656.20147-1-yan.y.zhao@intel.com> References: <20230714064656.20147-1-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) { /*