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 18420C27C41 for ; Wed, 16 Aug 2023 22:02:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346718AbjHPWCO (ORCPT ); Wed, 16 Aug 2023 18:02:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346700AbjHPWBy (ORCPT ); Wed, 16 Aug 2023 18:01:54 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BAD6F2 for ; Wed, 16 Aug 2023 15:01:53 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id d2e1a72fcca58-68874e3d89dso354548b3a.1 for ; Wed, 16 Aug 2023 15:01:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1692223313; x=1692828113; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=VBWbG2QXVJxk1xBNtiZNPqeLW4yQOwcqBAAuTBoWz9U=; b=7yK6nlaM2bwfZv5iDk55eg/lYYmEMSRwr5atiJ9WsovSYfY6fGKBta1lCVV5aYmckx 8yiK7t4Mnw7iEtfTm+A/AS/UWyV04DZ6eCMFcUlVCTukikXQ2nQReiDspIg0QLMfdeNh Vo+mRcwX4BB4+cwTZFtze9vU0E+AIPXkdiAa6jK0c+CSjkqfh5EhgZJqArNlxkT67s1N FOX1ciMZYoN69DRgFDrhaIo7CdclnhjU1gKdTZxxtN5RVk3JXGBAEo4f+yAy1mlhKWT/ dk28REorXDFlkSUKQVLek5hAhV4UWkkuGsfDVY9gXz0+ZnZpwmJFLzSnZpP0RWB2NaPS 1rDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692223313; x=1692828113; 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=VBWbG2QXVJxk1xBNtiZNPqeLW4yQOwcqBAAuTBoWz9U=; b=DCXfkzWQueSXAnJPWkC3OK2dfJNNyyviG77jISNB6wrwGEdnxkHfmfeT3fTFSl6PJp Xf5KvQ4cileuYjw2gMTEJWwi7QE/gJynzqHCQ36cM/RfTGeDHH/0ude3wUuCNiPyuAqb lGayqTRNJNyjJ+rwEZvnvqNSkBu1FuDGLOQdBXY7r8utE7rEy2Q91omDUelriJbyKjj+ /dmaFI88SyPTFbf1Dp7xlFQSuoaE0k+J85kpvAzYqYuAu4tmdlI4Q4w5lm4BGuOBFKRL HzCG6Ar1orlPBsQgRB32h+JWEWYgZkjObbo5bF9rcMVkK90/H2FguuY2fX5ygSlDgB4n L5aQ== X-Gm-Message-State: AOJu0YybZ1Nfd/5xn/CFvKdwRDPaGNcDdxFCEox2xADqbLslXkFgiAOV 1FEUM57zuzGHov58g4877xkdhE0GlYg= X-Google-Smtp-Source: AGHT+IECGuILJhGG7M10tme6mh4YKaUBjEHoQvuTjBLw+EFSHmvpxYXkTjIEzuG1aw08h29gjmonNn4jiJY= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:9a0:b0:687:5274:da17 with SMTP id u32-20020a056a0009a000b006875274da17mr414480pfg.2.1692223312805; Wed, 16 Aug 2023 15:01:52 -0700 (PDT) Date: Wed, 16 Aug 2023 15:01:51 -0700 In-Reply-To: <20230719144131.29052-8-binbin.wu@linux.intel.com> Mime-Version: 1.0 References: <20230719144131.29052-1-binbin.wu@linux.intel.com> <20230719144131.29052-8-binbin.wu@linux.intel.com> Message-ID: Subject: Re: [PATCH v10 7/9] KVM: VMX: Implement and wire get_untagged_addr() for LAM From: Sean Christopherson To: Binbin Wu Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, chao.gao@intel.com, kai.huang@intel.com, David.Laight@aculab.com, robert.hu@linux.intel.com, guang.zeng@intel.com Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Jul 19, 2023, Binbin Wu wrote: > + return (sign_extend64(gva, lam_bit) & ~BIT_ULL(63)) | (gva & BIT_ULL(63)); Almost forgot. Please add a comment explaning how LAM untags the address, specifically the whole bit 63 preservation. The logic is actually straightforward, but the above looks way more complex than it actually is. This? /* * Untag the address by sign-extending the LAM bit, but NOT to bit 63. * Bit 63 is retained from the raw virtual address so that untagging * doesn't change a user access to a supervisor access, and vice versa. */