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 9DDBAC77B7A for ; Thu, 18 May 2023 09:32:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230095AbjERJcn (ORCPT ); Thu, 18 May 2023 05:32:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230027AbjERJcj (ORCPT ); Thu, 18 May 2023 05:32:39 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7AF741990; Thu, 18 May 2023 02:32:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1684402356; x=1715938356; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=ufC3GRA8nPg5qrCMUy5LcfZUCIfhhLVoJdgjOUeXBI0=; b=aedFIOrwH6fDk4Y6PpJj4Y2A4UxzBemDge7EQ+3QT5lsjx8HxPeacNVx t4mAJdPwXlitE/oz2NPL8CXQm83y6m6XA06e1kV7etZRHwJTIwQ9zV8/F Og3ueWtNNGaIWTWi31Hl1aryQ+wF3rhzBa0LFod7mxUtwfERMAaZWwJp/ d+RmLCIZOsTHgUVLG16PqUIA4skmdhUk1OGHBQeR3vlT34wHKOfKhUrj6 AVlrw/3ZTxf0CG0K/05dFbveAanSvmAZN90n8FKSRNnVF2CioyhQ/4QOs 3rYassVzV3hgI7nBY0tt1riwehiKMRwSLPf4crj8RbGXF7RT36eTh+Lyx w==; X-IronPort-AV: E=McAfee;i="6600,9927,10713"; a="350854788" X-IronPort-AV: E=Sophos;i="5.99,284,1677571200"; d="scan'208";a="350854788" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2023 02:32:36 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10713"; a="771809523" X-IronPort-AV: E=Sophos;i="5.99,284,1677571200"; d="scan'208";a="771809523" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.254.211.142]) ([10.254.211.142]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 May 2023 02:32:33 -0700 Message-ID: Date: Thu, 18 May 2023 17:32:31 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.10.1 Subject: Re: [PATCH] KVM: x86: Track supported ARCH_CAPABILITIES in kvm_caps Content-Language: en-US To: Chao Gao , kvm@vger.kernel.org Cc: Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org References: <20230506030435.80262-1-chao.gao@intel.com> From: Xiaoyao Li In-Reply-To: <20230506030435.80262-1-chao.gao@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/6/2023 11:04 AM, Chao Gao wrote: > to avoid computing the supported value at runtime every time. > > No functional change intended. the value of kvm_get_arch_capabilities() can be changed due to if (l1tf_vmx_mitigation != VMENTER_L1D_FLUSH_NEVER) data |= ARCH_CAP_SKIP_VMENTRY_L1DFLUSH; and l1tf_vmx_mitigation can be runtime changed by vmentry_l1d_flush module param. We need a detailed analysis that in no real case can ARCH_CAP_SKIP_VMENTRY_L1DFLUSH bit change runtime. > Signed-off-by: Chao Gao > --- > > A new call site of kvm_get_arch_capabilities() is added by [1]. It should be > replaced with the cached value in kvm_caps. > > [1] https://lore.kernel.org/all/20230504181827.130532-1-mizhang@google.com/ > > > arch/x86/kvm/x86.c | 5 +++-- > arch/x86/kvm/x86.h | 1 + > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 523c39a03c00..94aa70ec169c 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1670,7 +1670,7 @@ static int kvm_get_msr_feature(struct kvm_msr_entry *msr) > { > switch (msr->index) { > case MSR_IA32_ARCH_CAPABILITIES: > - msr->data = kvm_get_arch_capabilities(); > + msr->data = kvm_caps.supported_arch_cap; > break; > case MSR_IA32_PERF_CAPABILITIES: > msr->data = kvm_caps.supported_perf_cap; > @@ -9523,6 +9523,7 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops) > kvm_caps.max_guest_tsc_khz = max; > } > kvm_caps.default_tsc_scaling_ratio = 1ULL << kvm_caps.tsc_scaling_ratio_frac_bits; > + kvm_caps.supported_arch_cap = kvm_get_arch_capabilities(); > kvm_init_msr_lists(); > return 0; > > @@ -11879,7 +11880,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) > if (r) > goto free_guest_fpu; > > - vcpu->arch.arch_capabilities = kvm_get_arch_capabilities(); > + vcpu->arch.arch_capabilities = kvm_caps.supported_arch_cap; > vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT; > kvm_xen_init_vcpu(vcpu); > kvm_vcpu_mtrr_init(vcpu); > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h > index c544602d07a3..d3e524bcc169 100644 > --- a/arch/x86/kvm/x86.h > +++ b/arch/x86/kvm/x86.h > @@ -29,6 +29,7 @@ struct kvm_caps { > u64 supported_xcr0; > u64 supported_xss; > u64 supported_perf_cap; > + u64 supported_arch_cap; > }; > > void kvm_spurious_fault(void); > > base-commit: b3c98052d46948a8d65d2778c7f306ff38366aac