From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 049053C0634 for ; Thu, 4 Jun 2026 20:20:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780604432; cv=none; b=QjbNOciJMmj1uL+48lY4P2OfRfLNb9cNBylThm+/oK/6B6oymps/BqWlxn1Cd7c2gXRR7E1KwT9CRUaYDxIYxJQVc5jyZGtA7sqKFuzuNgnSffb4ZfOs4cFnPXrxHHf8DIXJWZd/syeMl0ghPbYwx0VFiqVyGOBqbdNUOvvY5qo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780604432; c=relaxed/simple; bh=uDuzNTF1ZSyLMYiOoa+3kMLHWZaw1Jm0DeWS6NCT25U=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=tui3OdB3EGsqXsnMzRhEx2E7JG4jcfBSpYK8NWCg+TY1+zCpME39NlfDRGg29srTc3QMb8GtWeEBjIK7Yu3d6KQqkb84uJm8WuA1qG4gTYB7adRTeYByGoBZ/H62NQCYQYTv9MqDmI4fXCa9BRim7cAl8YQ/aoONKugjY2Fy8ig= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=M5EG541W; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="M5EG541W" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-36d8719bae6so985936a91.3 for ; Thu, 04 Jun 2026 13:20:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780604430; x=1781209230; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=tgeZ0o5WGa6wb92jyP428hFVqKsbxK2JJNVhO+w+THo=; b=M5EG541WGAZi+iSKgBWjFUKlkQ7LBBMr7Gqr6jkCl8hsdjJxiJA5TPF1X2K3EWcJFx gATM4W/1yZD13GGPP7iH6TIPXi17opZyan4J5oqn9lN9hCG8TGvRtRx9nr7asadzr0o/ lsniiJ1QVdycY/kNNIAr8C34YuBDVDFKcEvhiYY31ifUbFIPMaEO4YdeWqLvx3626SNc 2MwKMqmr+FBU1YR2N6HL4AJL4HGh29k2zZJkCmHiMM8g9PeH6ypdB0g/48hKQyfmKyAY 82ec/FHt8LbuhDxGUvTtaWKYf2Tz1LKKEa0kXsu33oBrcPgb6oS2RtS+lyn3WyEjObhN 1ByA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780604430; x=1781209230; 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=tgeZ0o5WGa6wb92jyP428hFVqKsbxK2JJNVhO+w+THo=; b=Mt0iVvjZSehLjloiyF55K1ZxfcvpFpifG+mdqVzZW/Cc06o7zqqi8VJMaWIrZ/5B/p A3yeHG7EnpyidnQXT2uV7W8B3Q5PcQ1k3eQLAqoWuvTUsyU6DaYQVcpm60PEsxn53u2m GqIj8bzrBkzQX/xCYo71ar6QQR5sLL3OdCgHNMTYjmphEXsc9zVT75p1kvVPpa2T1EDt 5GBOXLnMF9Uvn8BxuJGRfxcOruvFIKruZ0KellUpb+cvbz33eU5GkTCiNWVQmN7WGy39 OIgmixbEt8lBYuhtExVzhI5sQpYH3BqrBrRMqGZVAMsnpw6D5PdbYhD30djejoOvB2Rz a35g== X-Forwarded-Encrypted: i=1; AFNElJ9D+fSY6GQQie3e5rM74IMeSZdE3zFBIHDWVVApJ3DWFbIeyWhlooZinwwn2z8MPp+erFbor8GMyAw=@vger.kernel.org X-Gm-Message-State: AOJu0YzgdyB6o00skVkN5YS3tbctnVs7U7zYQsRJIx4e7YeRduJFmv3z wznkmRQ8GJZ9rQYgCpQ8HDTxvWdlX7m8AJQqS0KSRNWruoJY32CsetnjKON3JVBbLjZN6IJSgIc xmf3XKA== X-Received: from pjao2.prod.google.com ([2002:a17:90a:1682:b0:365:d2b3:f703]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4b04:b0:36a:5d1f:7b6 with SMTP id 98e67ed59e1d1-370ee5444e7mr546764a91.2.1780604429941; Thu, 04 Jun 2026 13:20:29 -0700 (PDT) Date: Thu, 4 Jun 2026 13:20:29 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260522-gmem-inplace-conversion-v7-0-2f0fae496530@google.com> Message-ID: Subject: Re: [PATCH v7 00/42] guest_memfd: In-place conversion support From: Sean Christopherson To: Ackerley Tng Cc: Ackerley Tng via B4 Relay , aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, david@kernel.org, ira.weiny@intel.com, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, tabba@google.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Jason Gunthorpe , Vlastimil Babka , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev Content-Type: text/plain; charset="us-ascii" On Wed, Jun 03, 2026, Ackerley Tng wrote: > Ackerley Tng via B4 Relay > writes: > > > This is v7 of guest_memfd in-place conversion support. > > > > Here's the outstanding items after going over everyone's comments > including Sashiko's: > > + KVM: TDX: Make source page optional for KVM_TDX_INIT_MEM_REGION > + Need to move page clearing into __kvm_gmem_get_pfn to resolve > leak where populate can put initialized kernel memory into TDX > guest > + See suggested fix at [1] That fix works for me. The initial guest image will typically be a tiny subset of guest memory, so unnecessarily zeroing a few pages isn't a performance concern. > + KVM: guest_memfd: Only prepare folios for private pages, > + s/non-CoCo/CoCo in commit message "INIT_SHARED is about to be > supported for non-CoCo VMs in a later patch in this series > + Use Suggested-by: Michael Roth > + KVM: selftests: Test that shared/private status is consistent across > processes > + Improve test reliability using pthread_mutex > + I have a fixup patch offline. > > I would like feedback on these: > > + KVM: selftests: Test conversion with elevated page refcount > + Askar pointed out that soon vmsplice may not pin pages. Should I > pin pages through CONFIG_GUP_TEST like in [2]? I prefer not to > take a dependency on CONFIG_GUP_TEST. I'm not exactly excited about taking a dependency on CONFIG_GUP_TEST either, but it probably is the least awful choice. E.g. KVM also pins pages is certain flows, but we're _also_ actively working to remove the need to pin. Hmm, maybe IORING_REGISTER_PBUF_RING? AFAICT, it's almost literally a "pin user memory" syscall. > + KVM: selftests: Add script to exercise private_mem_conversions_test > + Would like to know what people think of a wrapper script before > I address Sashiko's comments. NAK to a wrapper script. This sounds like a perfect fit for Vipin's selftest runner (which I'm like 4 months overdue for reviewing, testing, and merging). If the runner _can't_ do what you want, then I'd rather improve the runner. [*] https://lore.kernel.org/all/20260331194202.1722082-1-vipinsh@google.com > > [1] https://lore.kernel.org/all/CAEvNRgEVC=fFuKVgZYvWyZD7t_zvUZihFG8hrACjvtkD5cwugw@mail.gmail.com/ > [2] https://lore.kernel.org/all/baa8838f623102931e755cf34c86314b305af49c.1747264138.git.ackerleytng@google.com/ > > > > > [...snip...] > >