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 17AB5D46BED for ; Thu, 29 Jan 2026 00:37:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BF8876B0088; Wed, 28 Jan 2026 19:37:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B7C296B0089; Wed, 28 Jan 2026 19:37:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A5D756B008A; Wed, 28 Jan 2026 19:37:58 -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 94BCE6B0088 for ; Wed, 28 Jan 2026 19:37:58 -0500 (EST) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id E0FBED459E for ; Thu, 29 Jan 2026 00:37:57 +0000 (UTC) X-FDA: 84383138994.28.60C0362 Received: from mail-qk1-f173.google.com (mail-qk1-f173.google.com [209.85.222.173]) by imf01.hostedemail.com (Postfix) with ESMTP id EF26A40008 for ; Thu, 29 Jan 2026 00:37:55 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=fCDu3GXh; dmarc=none; spf=pass (imf01.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.222.173 as permitted sender) smtp.mailfrom=jgg@ziepe.ca ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1769647076; a=rsa-sha256; cv=none; b=DSENkHiYFWUY/H6EXOptS8qe2fva4nfGol1mBSw5lOONf8NprzeQWXAb9cF3ijTNO8aZEJ vIL9x6zD2l9S6C8qmU2hyyaUXRzPrwmNNa5qP+NdasGGisvWOWdCvLAxzrgcFmReh2X+a4 36O8TkR5WdNUskI0HQRLiR6ZA3HVa80= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=fCDu3GXh; dmarc=none; spf=pass (imf01.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.222.173 as permitted sender) smtp.mailfrom=jgg@ziepe.ca ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1769647076; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=1OWzBPKnyrz01i64zQ4S/hZaAIPcGy0JKcdMQLZXMgA=; b=lnCKn13SI9RW13jef5vT2dNzrkrhWJJhZfsCRzfigHBPeUnKfnAG4T2Nb9p/Ddfq4Wcg9r I3dq2pT92itaUUky6WL86jJT37kVzgmAiA7qGdwoXL7tSPte/ySycpl1NO++rZyTERxBQf fUwpMsl4xLIaW1qIWSRrrZgobKU+rOs= Received: by mail-qk1-f173.google.com with SMTP id af79cd13be357-8c7146b0854so51156785a.2 for ; Wed, 28 Jan 2026 16:37:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1769647075; x=1770251875; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=1OWzBPKnyrz01i64zQ4S/hZaAIPcGy0JKcdMQLZXMgA=; b=fCDu3GXhaotvvxwKQp/BIHYH9WoLTm7lWFzLtakLNpg+amK07Dds9vQ8yEvYw43kiu EkTFDY6kXTVavDWH1Gx+9LdlhMhtUWyuOH5cTLg9VHU3IyGBoH6mhZm/Lbs6ZinL7BzA whMxSHX+tX4iOerFPdukZZ0cTiPvrxO+1Z90LDasfWFeJaIse/aLJOuvJtiU5Kthv5N9 nRGEXXv/+ANpntNyZUBySeHmghvL264hGiMzmXbPhDP2IqA/up6uNGRVvT3Sac8kptym e4XBDrnuwQm/tV17KGY0DJ46/JoYd5qjO3GmmvJnS9gzw93JPs9reNovsGj2zPmSNVQ1 phlw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769647075; x=1770251875; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=1OWzBPKnyrz01i64zQ4S/hZaAIPcGy0JKcdMQLZXMgA=; b=ivBdeG6GUq5j2ndSJsmGKu4CRNHrfOYhr9g2ElVlKUYSsFZ/rxwH7At32OcF1gu7Xs MvmTcuJn5tSRaJw0M2HeJ+MHLfXGY7xPIum8elSeal3lZRyr9KxMlPOaPU+2cLn4ba8B c+g3XGpVQXfe7EDjx68smJV5as3FLcr5RS4BdoqOH6Ri2oaOxfgvrGaqkGfCC5FrhgiD ZkvryiTsDNlUeQkv0BsFLBnSi6H/QTQFqkioY+6Y7kmXsiTW74ETSlLAKoCdFex8Ixql kRWwJTfBNCkkErHuPazEC6FkqMBWbVAzkv0WFTt1W08PmsGuePmcZzzkG4rUScg9ti6w BVAw== X-Forwarded-Encrypted: i=1; AJvYcCWHAchHheS75Ljex70bMyOVBICN68Y+hPXwJiiSGjio1CfuJdOaKY+L0fnpmHexKW7WOXMWQ+DByA==@kvack.org X-Gm-Message-State: AOJu0Yyr0SdA5xq7aE66llEz7L+j4lkoSulpIIZ1npBd5feJPUuXI07x gXFAUWwTAXYAqQ+nCvPhIt0mUreAJUMaqgSKKoZlAUr2tAFvlZgO7nqGhHSbzIE3GvI= X-Gm-Gg: AZuq6aKcd7o+aVpqkQeLQck8xVsZnvDiCex+lsGTN+1QV5odILg0DcYRfnsRhAW4BMI 0jVrweiWhe6hh3vZtxGfr1zpDJTEtTZ+FHrnha+Ul4qPyA1c3OxgyowvhI8GZAQd08I4jaGO2W2 Luuo1xbao50I11mVtAjymhPZPdgbyYtBFwUjsAaJIFtgTxNeirZtFnm32gMUodF3xbA6XlSGwob xU5iW8O3J3fOQOE9p8TV/f9P2G1KIAaxwLBNw96STzRhR9abTaIdhtT6dQ1iWDvo2CJFulhd1As lIypREejYLuK2N4CmwjQVeFcDcKpaPRkNOkFf9W+WNiTQuEnP+0Zt2bF91bzc2entVfzhdDe7yt ndo7R2UvcWqBQ8WDIXLgt74f4HzsnbYL0OBz4XYtjpsfJGPplQ+kr4jsPAgXb40dZ1BNaSwLYl/ 8jZm4XjBaLcJfx39+JDGxjEEpjNX6nobhXDzb0wV62XJEJfwp2hFYFyplEfESciY7YlT0= X-Received: by 2002:ae9:c202:0:b0:8c7:126e:e901 with SMTP id af79cd13be357-8c7126eeb1amr465687985a.22.1769647074488; Wed, 28 Jan 2026 16:37:54 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-112-119.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.112.119]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c711d29aa2sm294243485a.35.2026.01.28.16.37.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jan 2026 16:37:53 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vlG2j-00000009g5p-04Lm; Wed, 28 Jan 2026 20:37:53 -0400 Date: Wed, 28 Jan 2026 20:37:53 -0400 From: Jason Gunthorpe To: Ackerley Tng Cc: Alexey Kardashevskiy , cgroups@vger.kernel.org, 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, linux-trace-kernel@vger.kernel.org, x86@kernel.org, akpm@linux-foundation.org, binbin.wu@linux.intel.com, bp@alien8.de, brauner@kernel.org, chao.p.peng@intel.com, chenhuacai@kernel.org, corbet@lwn.net, dave.hansen@intel.com, dave.hansen@linux.intel.com, david@redhat.com, dmatlack@google.com, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, haibo1.xu@intel.com, hannes@cmpxchg.org, hch@infradead.org, hpa@zytor.com, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maobibo@loongson.cn, mathieu.desnoyers@efficios.com, maz@kernel.org, mhiramat@kernel.org, mhocko@kernel.org, mic@digikod.net, michael.roth@amd.com, mingo@redhat.com, mlevitsk@redhat.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, peterx@redhat.com, pgonda@google.com, prsampat@amd.com, pvorel@suse.cz, qperret@google.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, rostedt@goodmis.org, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shakeel.butt@linux.dev, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, tabba@google.com, tglx@linutronix.de, thomas.lendacky@amd.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, wyihan@google.com, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Subject: Re: [RFC PATCH v1 05/37] KVM: guest_memfd: Wire up kvm_get_memory_attributes() to per-gmem attributes Message-ID: <20260129003753.GZ1641016@ziepe.ca> References: <071a3c6603809186e914fe5fed939edee4e11988.1760731772.git.ackerleytng@google.com> <07836b1d-d0d8-40f2-8f7b-7805beca31d0@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: EF26A40008 X-Stat-Signature: nq8yy7aydifqe6ewfjjgfgaoa7u9sq8g X-HE-Tag: 1769647075-122237 X-HE-Meta: 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 ruafkqPx 5s1/0HYQYs1k1ZfQdJiFxlAjQ3qGcbwrdAm0J0u0wnHjimT9wMCzAn0bR/AoQVSeZ0+PdRZl6tWdfQOb+Fvmu2Lfjcpe/dNNt2g+Ry3aNt524n8IIrZz6ueIO8BQPZT7aUYS4uXY6k9A8D/t+kWc0e3z/AT9ICkAAEra0W9SbYgBxsA3CvgYxATXYQ1ET3GKyiUCZtQ0FWpP5wB35T0wF9Z1lEQBLq0R9pVJDLc8ojPNg/ekgpE7Tw7b+Li6oM3fwRfk9hNatY9hC72htujZdvCN7TTGDU4RuhvH08KdG/CG/ia+SZz0rG+JIxhzniqRotT5kqxjBNL3ekDL3AbY7nrZ8N/4YXQJylT/IOyT8FRKHScWpYKD19C3wmh2S5uyj2EBXyXJwx/hOu4/0Qitja5Z/cGwMOXFbUeX0McrJ88S1B+o= 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: On Wed, Jan 28, 2026 at 01:47:50PM -0800, Ackerley Tng wrote: > Alexey Kardashevskiy writes: > > > > > [...snip...] > > > > > > Thanks for bringing this up! > > > I am trying to make it work with TEE-IO where fd of VFIO MMIO is a dmabuf fd while the rest (guest RAM) is gmemfd. The above suggests that if there is gmemfd - then the memory attributes are handled by gmemfd which is... expected? > > > > I think this is not expected. > > IIUC MMIO guest physical addresses don't have an associated memslot, but > if you managed to get to that line in kvm_gmem_get_memory_attributes(), > then there is an associated memslot (slot != NULL)? I think they should have a memslot, shouldn't they? I imagine creating a memslot from a FD and the FD can be memfd, guestmemfd, dmabuf, etc, etc ? > Either way, guest_memfd shouldn't store attributes for guest physical > addresses that don't belong to some guest_memfd memslot. > > I think we need a broader discussion for this on where to store memory > attributes for MMIO addresses. > > I think we should at least have line of sight to storing memory > attributes for MMIO addresses, in case we want to design something else, > since we're putting vm_memory_attributes on a deprecation path with this > series. I don't know where you want to store them in KVM long term, but they need to come from the dmabuf itself (probably via a struct p2pdma_provider) and currently it is OK to assume all DMABUFs are uncachable MMIO that is safe for the VM to convert into "write combining" (eg Normal-NC on ARM) Jason