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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1B155D2FED1 for ; Wed, 28 Jan 2026 00:29:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2BCFD6B0005; Tue, 27 Jan 2026 19:29:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 26AA86B0089; Tue, 27 Jan 2026 19:29:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0F7EF6B008A; Tue, 27 Jan 2026 19:29:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id F3C3A6B0005 for ; Tue, 27 Jan 2026 19:29:09 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 9CC178B7ED for ; Wed, 28 Jan 2026 00:29:09 +0000 (UTC) X-FDA: 84379488018.18.FD7A2FF Received: from mail-vs1-f43.google.com (mail-vs1-f43.google.com [209.85.217.43]) by imf26.hostedemail.com (Postfix) with ESMTP id 90422140003 for ; Wed, 28 Jan 2026 00:29:07 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=2XxIxhKH; spf=pass (imf26.hostedemail.com: domain of ackerleytng@google.com designates 209.85.217.43 as permitted sender) smtp.mailfrom=ackerleytng@google.com; dmarc=pass (policy=reject) header.from=google.com; arc=pass ("google.com:s=arc-20240605:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1769560147; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=afdfdT2YOMsD0iZJQSrtAQ+axiAIWjxn1C3TT/YCmDM=; b=3RZo+AYxS52luaMsK3FFXwHQaPiATG7+JAV2RkYL7oH1EPf+JO9wbLBS3DQvPAHT2DtQjt ljHSFuypCXcMqA18IRkee6x9dWvTHlfGxAM68YUSLRWiEDWbH0FQdiXd24DDKSNgA62sJN XyMzUvyHEBRfmzhYekmYbqRek6hWZ0c= ARC-Authentication-Results: i=2; imf26.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=2XxIxhKH; spf=pass (imf26.hostedemail.com: domain of ackerleytng@google.com designates 209.85.217.43 as permitted sender) smtp.mailfrom=ackerleytng@google.com; dmarc=pass (policy=reject) header.from=google.com; arc=pass ("google.com:s=arc-20240605:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1769560147; a=rsa-sha256; cv=pass; b=SSj7/zo3fF7SLk+r2rshNgNMzfkgHgYHzulmx7fV80gKUg/3vrEykpa0VKvmw/7cNhYwyf mf9Yk6SGq0MWBXXK/dMYMf0BFkk4I86N7Y/TXo+dyfbfo5dWJIvjo/ZhS1/wmLJqrDrQrk 50GSHBgLw4L3KWrkj8dynO1kmTckOz0= Received: by mail-vs1-f43.google.com with SMTP id ada2fe7eead31-5f53021703aso2151863137.3 for ; Tue, 27 Jan 2026 16:29:07 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1769560146; cv=none; d=google.com; s=arc-20240605; b=eVsB6KNW+x+Lmi4HRWu/vA9reedkarDb7UTrdcuSpYL5o9gVWb3ZB34xYwD/BXMoJ2 Qfczw3HHiYX99NOp7Jrg8ARLakS+oQ+WfTRjM+UcAW3gfTBcaRglXbU940Gn6cjEkZrj mft2gGzCrygI5L/4auDJ1FBbrhe7XvUZL8E/H2QqTu5U3LKrp8djmUftXiCAyayaIkwV zY2xYe7CCYy10VkgYgUCrEjuqSzF7H5uX2zRHL/ZJrj5F74bLnwVIgNf5Y6jhC9eCSMW 8LZCuUQEvytHFSNDfu6ToF6wfzMT++C1dIHTeASrTKidKonKuZipcGVFI08YhC5lcRan s63A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605; h=content-transfer-encoding:cc:to:subject:message-id:date :mime-version:references:in-reply-to:from:dkim-signature; bh=afdfdT2YOMsD0iZJQSrtAQ+axiAIWjxn1C3TT/YCmDM=; fh=K5DAYv9x12g7fuZwfE8xTRldWbw45HZNpBOLBG5ar+A=; b=cAkmwcoSE7redXz0Chhbc110DddoJGfHgnNDIC7VF1NgL0Ms6TT0dFApUSK6vSLKLO zr1r5yO3BAv9Wweob1OYZKwPDnClnTD+0429sTlX/xeefAd5TP5X9WESrgHBuc6g1wCq yDSVpSnMYb9gqVq+tMbIJXOI/stbTF/8AQeAI02l7D+hPwgsEOyk6Cgwm476/1triIAG ZfBL8Sc6U+7VkUWeW0qp0s5Lx5p2xBfqHBwWu7iJcsFpCXROzEeNTKagcgemKhfoNnpx 4yrYfYypIgjohsfLGu8kwOmzGRlhnzz+TPxkm9gdCw0MwcAqDUJcj1ue0EpPEIO8ui7R 1qoA==; darn=kvack.org ARC-Authentication-Results: i=1; mx.google.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1769560146; x=1770164946; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date :mime-version:references:in-reply-to:from:from:to:cc:subject:date :message-id:reply-to; bh=afdfdT2YOMsD0iZJQSrtAQ+axiAIWjxn1C3TT/YCmDM=; b=2XxIxhKHnApwIlM582rzYEQeJRE4gOfJfonIlHcTe2cFj0NGPzrF4y6jJ/CS1pjZDS f4aDhDDTmsfK15hnJqMBwpveDCKYnr1rHS1egGmN2w7HJRGZ7P5N+FuGSzHDxZGJvUml UGkAWRc6LUve1SxoDuNvvi1Bj27nVLI63vVDXGGrr2NVSAI7qGBdvvD/PudoPvgDpjds KazRZboV5zy6CXwgkwDwbbmsLNALl14zVS3am98RWOgKTmh1eLS0mNZl5+7A+7XOxDUT hy57D0awmGnR94Z9ROvOc0x42IvMXVRuQJYIl67ppRPPds8Op8luxpr00yFzRcno/86r O6Pw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769560146; x=1770164946; h=content-transfer-encoding:cc:to:subject:message-id:date :mime-version:references:in-reply-to:from:x-gm-gg:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=afdfdT2YOMsD0iZJQSrtAQ+axiAIWjxn1C3TT/YCmDM=; b=fkYJUB/lOVLexKxSAihEWAF/DzmI1o8A0zxNL/fvFAcsnQl/lQ59ianGfDYxxcW7wk 0TU1hTY9voZcG44W5EQWaq4XXamSSpl2kRu2x1oJ/g/OKBmcg8pq5cSA6iifzVRAEFzB rhNiplgrFZeWzvoqcLwH8TFnZUMP5Dc6PYkwtlrTjjBVmXW3r7IIWOsXjF7LFME/5dRO lDiR92WM6de+oGv0NkQc+WbhYbqHTt0g51iM9kLklbqoejryDtg3pO8n71uJAXjfVQD8 thmm4VkpaVbcV07s7hj1CvRKXDEtTvSC0bO7mf49BVNjEM+XuGw0tZ1ookSQE0vRHv++ C63A== X-Forwarded-Encrypted: i=1; AJvYcCVBDQViFoXOhY5Sp4YCr5D25Yg7X/wIx3xgD6bWKtwOWGJv5EWsQLsf7YK3yKXxfqSsiQp1pTu7tw==@kvack.org X-Gm-Message-State: AOJu0YxEaWAbzzIb08hfj6SpcZFm0aPHHf41NoCmqjNN94QFlvtj+jBv I1ZsOyphSgN2roIboR8hm7Gj9f/GzBT/ZTyNQEj0MvmpZrfRl/dUwWqknOwMDnJAgMPvHN3fXVG 8RQUlVSkqiGTOktDYjVE3gb+j1yLzd4kri0qehXPv X-Gm-Gg: AZuq6aJKb1TL8MIQ6StqvZi8aK07dx53B7N2xG3PUWhoMuCpOF2BKQPnGYtTB1bUHj6 A0JcHU+LcLMMe+xaSVR2CUinwklhg7T38kmRpdjllN1U0gmrT/yZEOBD1YBHvs1uax95z0JqYWT a7NR+mCkXvztlhD5HixhMoSfQvBcXHnI9CZvFKCeiKt4jiHiGHVUhZiMW4QTUH92XB/Uxk9IW9X +ch3MVRzjh1NnpzjkAdUSsk2BUM8AVcPnPaIBMJDTegExpOgfMM3At1joxX47yOihNoqEYNE4im +946IxVJw6mtzdwH53WTAXS8yiDoePE58Wtu X-Received: by 2002:a05:6102:94f:b0:5db:cba0:941 with SMTP id ada2fe7eead31-5f72380ed5bmr1335024137.38.1769560145803; Tue, 27 Jan 2026 16:29:05 -0800 (PST) Received: from 176938342045 named unknown by gmailapi.google.com with HTTPREST; Tue, 27 Jan 2026 16:29:05 -0800 Received: from 176938342045 named unknown by gmailapi.google.com with HTTPREST; Tue, 27 Jan 2026 16:29:04 -0800 From: Ackerley Tng In-Reply-To: References: <20260114134510.1835-1-kalyazin@amazon.com> <20260114134510.1835-8-kalyazin@amazon.com> <8c1fb4092547e2453ddcdcfab97f06e273ad17d8.camel@intel.com> MIME-Version: 1.0 Date: Tue, 27 Jan 2026 16:29:04 -0800 X-Gm-Features: AZwV_Qi5-DP-v6wjOnL-aDMsdDCx4XY7-YGdXQ0tP6_jJk0lLjibrIAwkazF3pk Message-ID: Subject: Re: [PATCH v9 07/13] KVM: guest_memfd: Add flag to remove from direct map To: "Edgecombe, Rick P" , "Annapurve, Vishal" Cc: "david@kernel.org" , "kvm@vger.kernel.org" , "catalin.marinas@arm.com" , "svens@linux.ibm.com" , "jgross@suse.com" , "bpf@vger.kernel.org" , "surenb@google.com" , "vbabka@suse.cz" , "riel@surriel.com" , "pfalcato@suse.de" , "x86@kernel.org" , "rppt@kernel.org" , "thuth@redhat.com" , "borntraeger@linux.ibm.com" , "maz@kernel.org" , "palmer@dabbelt.com" , "ast@kernel.org" , "peterx@redhat.com" , "alex@ghiti.fr" , "pjw@kernel.org" , "dave.hansen@linux.intel.com" , "tglx@linutronix.de" , "hca@linux.ibm.com" , "willy@infradead.org" , "wyihan@google.com" , "ryan.roberts@arm.com" , "jolsa@kernel.org" , "yang@os.amperecomputing.com" , "jmattson@google.com" , "aneesh.kumar@kernel.org" , "luto@kernel.org" , "haoluo@google.com" , "patrick.roy@linux.dev" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "coxu@redhat.com" , "mhocko@suse.com" , "linux-kselftest@vger.kernel.org" , "mlevitsk@redhat.com" , "jgg@ziepe.ca" , "loongarch@lists.linux.dev" , "song@kernel.org" , "oupton@kernel.org" , "Liam.Howlett@oracle.com" , "kernel@xen0n.name" , "Jonathan.Cameron@huawei.com" , "lorenzo.stoakes@oracle.com" , "jhubbard@nvidia.com" , "jthoughton@google.com" , "martin.lau@linux.dev" , "Yu, Yu-cheng" , "peterz@infradead.org" , "kvmarm@lists.linux.dev" , "eddyz87@gmail.com" , "hpa@zytor.com" , "yonghong.song@linux.dev" , "linux-doc@vger.kernel.org" , "shuah@kernel.org" , "chenhuacai@kernel.org" , "prsampat@amd.com" , "kevin.brodsky@arm.com" , "maobibo@loongson.cn" , "shijie@os.amperecomputing.com" , "suzuki.poulose@arm.com" , "itazur@amazon.co.uk" , "pbonzini@redhat.com" , "yuzenghui@huawei.com" , "gor@linux.ibm.com" , "dev.jain@arm.com" , "daniel@iogearbox.net" , "jackabt@amazon.co.uk" , "agordeev@linux.ibm.com" , "andrii@kernel.org" , "mingo@redhat.com" , "linux-riscv@lists.infradead.org" , "aou@eecs.berkeley.edu" , "joey.gouly@arm.com" , "derekmn@amazon.com" , "xmarcalx@amazon.co.uk" , "linux-s390@vger.kernel.org" , "kpsingh@kernel.org" , "kalyazin@amazon.co.uk" , "linux-arm-kernel@lists.infradead.org" , "sdf@fomichev.me" , "jackmanb@google.com" , "bp@alien8.de" , "corbet@lwn.net" , "linux-fsdevel@vger.kernel.org" , "jannh@google.com" , "john.fastabend@gmail.com" , "kas@kernel.org" , "linux-mm@kvack.org" , "will@kernel.org" , "seanjc@google.com" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 90422140003 X-Stat-Signature: wo3zfpnk6rd6hsg6q1n3eren447pig9j X-Rspam-User: X-HE-Tag: 1769560147-461162 X-HE-Meta: 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 ZiWUXHPj 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: "Edgecombe, Rick P" writes: > On Thu, 2026-01-22 at 14:47 -0800, Ackerley Tng wrote: >> >> There's no use case I can think of for unmapping TDX private memory >> from the host direct map, but Sean's suggestion >> https://lore.kernel.org/all/aWpcDrGVLrZOqdcg@google.com/=C2=A0won't even >> let shared guest_memfd memory be unmapped from the direct map for TDX >> VMs. > > Ah! > >> >> Actually, does TDX's clflush that assumes presence in the direct map >> apply only for private pages, or all pages? >> >> If TDX's clflush only happens for private pages, then we could >> restore private pages to the direct map, and then we'd be safe even >> for TDX? > > Yes, just private pages need the special treatment. But it will be much > simpler to start with just blocking the option for TDX. A shared pages > only mode could come later. > > In general I think we should try to break things up like this when we > can. Kernel code is not set in stone, only ABI. I think it will lead to > overall faster upstreaming, because the series' can be simpler. I agree on splitting the feature up :), agree that simpler series are better. Perhaps just for my understanding, + shared pages =3D> not in direct map =3D> no TDX clflush + private pages =3D> always in direct map =3D> TDX performs clflush (I could put pages back into the direct map while doing shared to private conversions). Is everything good then? Or does TDX code not apply the special treatment, as in clflush only for private pages, as of now?