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 8780EECAAA3 for ; Fri, 26 Aug 2022 04:48:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244648AbiHZEs2 (ORCPT ); Fri, 26 Aug 2022 00:48:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58208 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244728AbiHZEsW (ORCPT ); Fri, 26 Aug 2022 00:48:22 -0400 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52C3BCE44E; Thu, 25 Aug 2022 21:48:21 -0700 (PDT) Received: by mail-pj1-x1034.google.com with SMTP id r14-20020a17090a4dce00b001faa76931beso7003237pjl.1; Thu, 25 Aug 2022 21:48:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc; bh=gWomNih8e6LKSH0jfDGvuNkG1/sn2irHoorr1tZHc14=; b=MoYj1/VkxWWCh7Do2ZejjP0fPvkVMB/8vXDLu5GOXFX2tMX2zxxpj2E8E+epVmhHv6 Ne64mxPnMk4HfJUGxm/nVw+iiQ2l9QVXja5AMZV9PzwTmvv17V3T5Nobk38UkY1N369C kx1/en9fwEANVmG6pBrGEMsrtcXbsCiriEF2FjIYJTzQudioO7Gm+aogGI0fTkaq2nK5 0quyVyP/X8FozZEZWGGdlzDO3C4NY2S7FsUcy2TNONs6QkgBNeV/CIYOsVQ5cOaYFiTx F8HJrgbw8TsLXZwsnPzTsOtZbH1pZ52eoghWvt2NsLNtfJDBctP8XE+BzXl3hhOrdiEe hx6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc; bh=gWomNih8e6LKSH0jfDGvuNkG1/sn2irHoorr1tZHc14=; b=iZbO5L6cy/DWASCji0hCv9sQcEUi3rWJWdqi8JK85RfCUCpS058pIrj+BD1zqWkjDT laGJV/h8Zljy1wlSpTI2sT9OiVe2l8Xoswzat1cibU8dk1/53FvEQwv0Amf+0B1kk75J MiJLBzX8eXfnuDt4j+XD01nUYVk9RH2QDi34dSnm7hCbnuxY5B/T2Uqg0rBtPaju0pF5 GibcbUDhD0uc9qIFS4HJZdG/IJIv6hcTP4s1PWEXxBOPGGuNljeC17ZpsZ77WBiCQb8B OuuxcAlrohdN12yxdcBAAzsJDk7v3GDC8WDG6iQWOBertZ9MKxop2QcMxmBF90TKfojK dLzw== X-Gm-Message-State: ACgBeo3PVk3NFWx68fMXaHQbi3YwPBvm/v5Ob+PGswDDCLE52RjaOjBm mbuAprdGhM3AfKcrVbCr2SM= X-Google-Smtp-Source: AA6agR4vHZzYPFX0fkT5JVvgc46od6kvuDrV9tXaZmu8YVbWw0sLXbqt9Es3DU9YXHfWwTVVmgv14A== X-Received: by 2002:a17:90a:7f89:b0:1fa:ad33:7289 with SMTP id m9-20020a17090a7f8900b001faad337289mr2432002pjl.173.1661489299947; Thu, 25 Aug 2022 21:48:19 -0700 (PDT) Received: from localhost ([192.55.55.51]) by smtp.gmail.com with ESMTPSA id x15-20020a62860f000000b0053640880313sm549570pfd.46.2022.08.25.21.48.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Aug 2022 21:48:19 -0700 (PDT) Date: Thu, 25 Aug 2022 21:48:17 -0700 From: Isaku Yamahata To: Sean Christopherson Cc: Binbin Wu , isaku.yamahata@intel.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com, Paolo Bonzini , erdemaktas@google.com, Sagi Shahar Subject: Re: [PATCH v8 018/103] KVM: TDX: Stub in tdx.h with structs, accessors, and VMCS helpers Message-ID: <20220826044817.GE2538772@ls.amr.corp.intel.com> References: <651c33a5-4b9b-927f-cb04-ec20b8c3d730@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 23, 2022 at 03:40:40PM +0000, Sean Christopherson wrote: > On Tue, Aug 23, 2022, Binbin Wu wrote: > > > > On 2022/8/8 6:01, isaku.yamahata@intel.com wrote: > > > +static __always_inline void tdvps_vmcs_check(u32 field, u8 bits) > > > +{ > > > + BUILD_BUG_ON_MSG(__builtin_constant_p(field) && (field) & 0x1, > > > + "Read/Write to TD VMCS *_HIGH fields not supported"); > > > + > > > + BUILD_BUG_ON(bits != 16 && bits != 32 && bits != 64); > > > + > > > + BUILD_BUG_ON_MSG(bits != 64 && __builtin_constant_p(field) && > > > + (((field) & 0x6000) == 0x2000 || > > > + ((field) & 0x6000) == 0x6000), > > > + "Invalid TD VMCS access for 64-bit field"); > > > > if bits is 64 here, "bits != 64" is false, how could this check for "Invalid > > TD VMCS access for 64-bit field"? > > Bits 14:13 of the encoding, which is extracted by "(field) & 0x6000", encodes the > width of the VMCS field. Bit 0 of the encoding, "(field) & 0x1" above, is a modifier > that is only relevant when operating in 32-bit mode, and is disallowed because TDX is > 64-bit only. > > This yields four possibilities for TDX: > > (field) & 0x6000) == 0x0000 : 16-bit field > (field) & 0x6000) == 0x2000 : 64-bit field > (field) & 0x6000) == 0x4000 : 32-bit field > (field) & 0x6000) == 0x6000 : 64-bit field (technically "natural width", but > effectively 64-bit because TDX is > 64-bit only) > > The assertion is that if the encoding indicates a 64-bit field (0x2000 or 0x6000), > then the number of bits KVM is accessing must be '64'. The below assertions do > the same thing for 32-bit and 16-bit fields. Thanks for explanation. I've updated it as follows to use symbolic value. #define VMCS_ENC_ACCESS_TYPE_MASK 0x1UL #define VMCS_ENC_ACCESS_TYPE_FULL 0x0UL #define VMCS_ENC_ACCESS_TYPE_HIGH 0x1UL #define VMCS_ENC_ACCESS_TYPE(field) ((field) & VMCS_ENC_ACCESS_TYPE_MASK) /* TDX is 64bit only. HIGH field isn't supported. */ BUILD_BUG_ON_MSG(__builtin_constant_p(field) && VMCS_ENC_ACCESS_TYPE(field) == VMCS_ENC_ACCESS_TYPE_HIGH, "Read/Write to TD VMCS *_HIGH fields not supported"); BUILD_BUG_ON(bits != 16 && bits != 32 && bits != 64); #define VMCS_ENC_WIDTH_MASK GENMASK_UL(14, 13) #define VMCS_ENC_WIDTH_16BIT (0UL << 13) #define VMCS_ENC_WIDTH_64BIT (1UL << 13) #define VMCS_ENC_WIDTH_32BIT (2UL << 13) #define VMCS_ENC_WIDTH_NATURAL (3UL << 13) #define VMCS_ENC_WIDTH(field) ((field) & VMCS_ENC_WIDTH_MASK) /* TDX is 64bit only. i.e. natural width = 64bit. */ BUILD_BUG_ON_MSG(bits != 64 && __builtin_constant_p(field) && (VMCS_ENC_WIDTH(field) == VMCS_ENC_WIDTH_64BIT || VMCS_ENC_WIDTH(field) == VMCS_ENC_WIDTH_NATURAL), "Invalid TD VMCS access for 64-bit field"); BUILD_BUG_ON_MSG(bits != 32 && __builtin_constant_p(field) && VMCS_ENC_WIDTH(field) == VMCS_ENC_WIDTH_32BIT, "Invalid TD VMCS access for 32-bit field"); BUILD_BUG_ON_MSG(bits != 16 && __builtin_constant_p(field) && VMCS_ENC_WIDTH(field) == VMCS_ENC_WIDTH_16BIT, "Invalid TD VMCS access for 16-bit field"); -- Isaku Yamahata