From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.128.44 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792776231; b=21zxgk5cJfVhrTPitN7OU+x1EFObiK//ppxH6RY9vrl2Poc97uEmMx3cw18GzEZHRcKq dLrLK6nfgHwhiV7S5cSF9AMsL0GfTe/Djqq5Wnzr1nk7aTBQjyZoVE5f0GGjOWDHvbjrP BdknSkMjtHfyA6WOpCubFdAJmI2sTy0oLY99jBkT+I0M98qtjkEDFpE0wYeGhX0R3AR/T FvCkNP6uXbVJWL5TxHK4E+QfoAKkESog8Ei7Og9n5bwlZN3JrgLyFpMvQzhRtl+5FW4Rh GradzRYF9zWftjXIcca72eKp0Ty9/YqQ29mYoP7NZ37Lr7jEpteZMNEq2lA06VzCNxg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792776231; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: From:To:Cc:Subject:Date:Message-ID:X-Mailer:In-Reply-To:References: MIME-Version:Content-Transfer-Encoding; bh=b9U8BJjnSyQLu8vlmMN8CV+h3S1yPSnSBNwOLGcNxzs=; b=jDVeJvTLNXWgePRVMPitV3WcGz0KN1/MDDn3Wwsd8AlXerMcKq5KL/H0kVUbjtOAYX5r DMx4gOnXkK3H4BldF+v+pKOgQPN6vDJMlffDnQZ4Zv90qkYsdY3Okchkx/dtrDAGVbbhW 43ekSyFo8/DOgUEFBi6FBoWUQyJQRwIErF7BcAsbgcSTG0/nsiDhWjpl+OWQlSfREfJtL o4XGPorBYZAA1YqKHiJ8VvnefJB9U233z8d8tOAMIQofw0qbB9lHLNUa2rymhEkmpCS5I OTba6LbDx3r6FKEt1gVWX237R+yU8gtdVji0YSQfNoHCMTXSrxvxW3i8S32+mBwfcMw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b="m/lj/Off"; arc=none smtp.remote-ip=209.85.128.44 Received: from mail-wm1-f44.google.com (mail-wm1-f44.google.com [209.85.128.44]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F72E606A320 for ; Fri, 23 Oct 2026 17:23:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3F72E606A320 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=m/lj/Off Received: by mail-wm1-f44.google.com with SMTP id 5b1f17b1804b1-4a1e477fe16so8907965e9.1 for ; Fri, 23 Oct 2026 10:23:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1792776230; x=1793381030; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=b9U8BJjnSyQLu8vlmMN8CV+h3S1yPSnSBNwOLGcNxzs=; b=m/lj/OffyrqASJ7/+k2ndy3ARnMmZ4ngzDDHOfoxfIyRpwQk+KAsWUQg3rrdg+qaNN 3TFoyZ+aewF8WQz7pGfyEVXk5pHwaqut5XJ5xuFHCeBh7vAoOzdEgwybgifqnIAZykIF avAi8vIkMrmNGJPtKRcrpQfo9ODQv0n4tbspV4EXY1DvEzOb+OeH8TwDdedQ8F/jexXy rs4p9x1faefX53U5CkJj3x29eWfVs5Ga8NTm2vD010Jv9UP2rh6zuzJFkWQHRz18S/te y0hZ3bPqJeoOiYzcQCyxNZqytGu/jC/a9iGP3pmR3VmnMEoNj2iCNmhJDNd8HzM1Ilsh GG1Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792776230; x=1793381030; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=b9U8BJjnSyQLu8vlmMN8CV+h3S1yPSnSBNwOLGcNxzs=; b=EbII8b7W83vESTAz9eaBbI5f0cF/hzMakKUluJBxHbOu8fVUQAxBqzUAtA4pxEvj+5 /FPnKHV7qW79GWtO+xWvA65rhg+HJd2qSUqnmZ6cxKHglBAC6qlB6eJKSYVXbOHJ6Hrq T+e9lFxE+JdHlWrrdcWIs2mE2RHz4y0m25Ck4EIQaeUXM6J7iyRxNLDeBZRaGoavrUgY dDi8f9IH/UJdbti5f8JkbQVkrc+ItaEoiXcdmpO/EnwlVTWR5qn0TENx5FOaXmkC4rhN s6lz6JtIxNCzbSVpo1K5FIO6Cf+7e1DbaU83AKY8TLjoW4jLlIVoWTEQMRI/W9GkQnCS lqTQ== X-Forwarded-Encrypted: i=1; AKwUvBwCvmb5/M+orV3I9IoEdiCvCEJTlo5v14yUQeIHykmswfjbaIkPH7oS6NIlMB7B9HlDGbM=@vger.kernel.org X-Gm-Message-State: AFq9FYLDGE0B0cR5X2scU3s95xtGZUgVytQCmzg/kOTVQwMXnc1RCVsK ZP/RDIEMVW0NRpcyZY+C1RWQiLbFneRkC/8VZ7AA1K9FMaGIUIlXSgp1 X-Gm-Gg: AYBFou1XRdd0oWe1IUxfq62pINvjX580mwoCfmF4vIjsyWgjIJzZDk28X+MgKqX3zWG 42CS7xFcG8idLPNQyWr0FLgN/gJn7ZHYwmFwZoC/Da9I6b/fz65C5bdIyOjLnr4RK59rQ84lWqe 8py803mbHzAOSzoO2qdWNSxrxIPa9GIeMLccjwJGoh3FOjUBXrXJGUmvzL1ZxwaZfAPGZvDfgSB TaJLWFdz+3YScgrqZ4vd/Rw6201HRwhk+Q29mCb35jk62pdeHEo/rnMic80CZSwuHJbRKI97iRN mvG4WMeWLaeJYDgHogkNckAVrwK9KiCFf+0Hz89XcW96Fe2bC33WiZ2GP0IG7sG194ufV/y7x7f Sf1nIpqMsOY4kDdaYqnVHx9S0f+TgF0Kc5JAx5oscE+z1Z6pOXM4qvaVpHV1i9RvnfjjcqX4N7X rf55x8/w9pwKsstwBkUeMdAdjQCJSYAaizcPjLoEPU9I9KCUQHo+C3BZ9z/c2uJBK7gZYLL0dY3 PzzYI3l26oHMMI5SEt6RRtcUMNAYV1mZC19mjiIKIW2yWyGEegka2WIB1Tol98omFbC82+mw+pE hqwBTxrYFAhI7txaQuY9mPXSatldEN/J62NDj6XUYp+J561OdZtCW2o/aD0DPJa0NnGp16Mcqxt ARTJVJHq+ZxlfGX32 X-Received: by 2002:a05:600c:354c:b0:4a2:1197:1de0 with SMTP id 5b1f17b1804b1-4a211cb23f3mr50233895e9.19.1792776229374; Fri, 23 Oct 2026 10:23:49 -0700 (PDT) Received: from dev-dsk-fgriffo-1c-93421965.eu-west-1.amazon.com (54-240-197-234.amazon.com. [54.240.197.234]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a30764e9e7sm17932475e9.2.2026.10.23.10.23.47 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Oct 2026 10:23:48 -0700 (PDT) From: Fred Griffoul To: Ackerley Tng Cc: Alex Williamson , Alexander Graf , Alexander Viro , Alexey Kardashevskiy , Andrew Morton , "Aneesh Kumar K.V" , Ashish Kalra , Baolin Wang , Baolu Lu , Bill Wendling , Borislav Petkov , Catalin Marinas , Christian Brauner , =?utf-8?q?Christian_K=C3=B6nig?= , Connor Williamson , Dave Hansen , Dave Jiang , David Hildenbrand , David Rientjes , David Woodhouse , Erdem Aktas , Frank van der Linden , Gregory Price , "H. Peter Anvin" , Hugh Dickins , Ingo Molnar , Jacob Pan , James Houghton , Jan Kara , Jason Gunthorpe , Jianxiong Gao , Joerg Roedel , Joey Gouly , John Starks , Jonathan Corbet , Justin Stitt , Kevin Tian , Lorenzo Stoakes , Marc Zyngier , Michael Roth , Mike Rapoport , Nathan Chancellor , Nick Desaulniers , Nicolin Chen , Oliver Upton , Paolo Bonzini , Pratyush Yadav , Randy Dunlap , Robin Murphy , Samiullah Khawaja , Sean Christopherson , Shuah Khan , Steffen Eiden , Steven Price , Suzuki K Poulose , Tarun Sahu , Thomas Gleixner , Tom Lendacky , Tycho Andersen , Vishal Annapurve , Vlastimil Babka , Will Deacon , Xu Yilun , Yan Zhao , Zenghui Yu , x86@kernel.org, Shuah Khan , Fuad Tabba , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev Subject: Re: [PATCH RFC v2 31/50] KVM: guest_memfd: Support getting PFNs for stage 2 from providers Date: Fri, 23 Oct 2026 17:23:47 +0000 Message-ID: <20261023172347.88443-1-griffoul@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261022-gmem-alternative-providers-v2-31-5dd1dc6c660a@google.com> References: <20261022-gmem-alternative-providers-v2-0-5dd1dc6c660a@google.com> <20261022-gmem-alternative-providers-v2-31-5dd1dc6c660a@google.com> X-Mailing-List: kvm@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > + int (*get_pfn)(void *provider, pgoff_t index, unsigned long *pfn, > + int *max_order); Should get_pfn() also return attributes of the frame? Only the provider knows them, and every mapping of the frame has to follow them. Two examples: - Read only. A provider may lend a page that the guest can read but not write. I know you dropped this from the sample to keep things simple, but without it guest_memfd maps every frame writable, and there is no other way to make a guest_memfd page read only. - Aliased. The frame is also reachable somewhere else, e.g. a ring shared with a device. Such a frame must not become private; see my reply to 34/50. A u32 of flags, with 0 for today's behaviour, would cover both and leave room for more later. Fred