From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Date: Wed, 31 Jul 2024 13:36:25 -0700 Subject: [PATCH v12 01/84] KVM: arm64: Release pfn, i.e. put page, if copying MTE tags hits ZONE_DEVICE In-Reply-To: <87a5hxfs3d.fsf@draig.linaro.org> References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-2-seanjc@google.com> <87a5hxfs3d.fsf@draig.linaro.org> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Wed, Jul 31, 2024, Alex Benn?e wrote: > Sean Christopherson writes: > > > Put the page reference acquired by gfn_to_pfn_prot() if > > kvm_vm_ioctl_mte_copy_tags() runs into ZONE_DEVICE memory. KVM's less- > > than-stellar heuristics for dealing with pfn-mapped memory means that KVM > > can get a page reference to ZONE_DEVICE memory. > > > > Fixes: f0376edb1ddc ("KVM: arm64: Add ioctl to fetch/store tags in a guest") > > Signed-off-by: Sean Christopherson > > --- > > arch/arm64/kvm/guest.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > > index 11098eb7eb44..e1f0ff08836a 100644 > > --- a/arch/arm64/kvm/guest.c > > +++ b/arch/arm64/kvm/guest.c > > @@ -1059,6 +1059,7 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, > > page = pfn_to_online_page(pfn); > > if (!page) { > > /* Reject ZONE_DEVICE memory */ > > + kvm_release_pfn_clean(pfn); > > I guess this gets renamed later in the series. > > However my main comment is does lack of page always mean a ZONE_DEVICE? Nope. > Looking at pfn_to_online_page() I see a bunch of other checks first. Why > isn't it that functions responsibility to clean up after itself if its > returning NULLs? pfn_to_online_page() is more strict than gfn_to_pfn_prot(). At least in theory, gfn_to_pfn_prot() could return a pfn that has an associated "struct page", with a reference held to said page. But for that same pfn, pfn_to_online_page() could return NULL, in which case KVM needs to put the reference it acquired via gfn_to_pfn_prot(). From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (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 A97E8156F30 for ; Wed, 31 Jul 2024 20:36:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722458189; cv=none; b=XUJ0Uv5u8puAvLLVJ5p6bdU4mNqGnXZwH3QSSiWiQsUiilVWrsHNPsiZ5F9YIZQ2D2ZNxYd8eTYUgES9Z7cqir5SpYhheUhSt2CAsH96w6ea8JXc1JMjHmKFBHRQJZXsf5JJoz9vp0JHoF/ae7Op35HzOLLWxjr4gEy0XnzP6BM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722458189; c=relaxed/simple; bh=z1aLVeNoBym3Qjn/r9ThqGkDG4AOjTwKh0lTuQS/B+0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=gkj/4Res8kV9+mxm2wSw1qV4uMG41ANRZXNErHgkrIo/kyGqyeUkSYOGCYbfYF3XNs3NiF8T08lRWcDFsvazg7c+PDuf7Fv+R11dj0RdzTWgfezx7t4DeBBes1NbdHQAhZvVruaHDbc02PNpENN5jZuLthIergDvj9r2NC1YS/4= 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=JvNGKR2N; arc=none smtp.client-ip=209.85.128.201 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="JvNGKR2N" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-664aa55c690so124095597b3.2 for ; Wed, 31 Jul 2024 13:36:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1722458186; x=1723062986; darn=lists.linux.dev; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=Kd/mYHbPzOSIwsUM5m5UMPqJkKyWoklOLcVSOqbILGs=; b=JvNGKR2NUA8x0vJnM8G6j2bHRRiqpfozh6wYAfncdDQ4QTSDVvGLNfz46piz+hA9y6 MBAqiucOeN+laHZiQLoDIlY7y3d46Lb46GCY7fMcAen35Mdj+KB3r6OaJHeaIggHPPn7 ElIFr9Q6BxWN2Dj1A4yUUogPjqvUAmhdmJbG/U+Nchdta/rUrdk1fG3SRkRR48Fc8gRi s0l7Z/bsVWumh2cZocEHISx8fvpqtdDjCrntoQEmhnR86dWaruufEhf6Unq+lVK5IUhV q1Y6aXPtMg+RNVj8bZ/wSBcw2nK9xjyRQPcJvwNY+/h5NFaN3W6fPzf2Jw916jdZFRgj WSvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722458186; x=1723062986; h=content-transfer-encoding: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=Kd/mYHbPzOSIwsUM5m5UMPqJkKyWoklOLcVSOqbILGs=; b=bC5SarqrPrZjtIO6MVQk3flPRL3Wpnuy1uBFawwTCKHeQuGnPCVxgrKTt+uihYwA4a 0SWmY+b/IpTXxFYaIxxarMiQID12uEd0jGva5wM3huZCep29tCAo/OLMlj66gVjPYTeg frw9bmMInHm+QBTo+k05yzard9Stjl+1SLYR2VRIg3+Cshr5bHu3RI4NupcAoMV7cIgU 4S3Hpo5ToItAMdKxD8PSqNU2eQWQu7cKDtbUmJrxU4G7DTE/LOUUZ05Cfz0PBSGZLj3z Kvbpu+UoIouEDZqjr4fEpp8UHNQqjtjAfGeSvyAKU92FjJqqP3mMf2SkhOsZAMgIEN70 /xzA== X-Forwarded-Encrypted: i=1; AJvYcCUP61z3Z0WN+wvHFj38zEbT3IVW1ij1kOwCfZXWTDpXjaEcyDwJcEBjqQcbp5K6L2jgi43tsn9N1Qmi5HPxgLm82gL1O64I X-Gm-Message-State: AOJu0YzLTl0bK0qTXe6NO/jUaGmn6XZMUxW8+IyLjD9f5almEEvuqaRJ d2xDFPYK19OkZ4kRz9PdxQ7XLbx6GYLCWRC0eA1IPRSGLqg89KrvY/37q7SbDxLsa82TdPPpiTm yNA== X-Google-Smtp-Source: AGHT+IH0DRpeCdEjd5+EVXte2iiNPB7q7dTvECq86U0Z8nMo4fguKYduL9RXt42ZsXAM2SH8mq6gA4JZJ0k= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:18d2:b0:e0b:bf20:4ff8 with SMTP id 3f1490d57ef6-e0bccf7b434mr932276.0.1722458186501; Wed, 31 Jul 2024 13:36:26 -0700 (PDT) Date: Wed, 31 Jul 2024 13:36:25 -0700 In-Reply-To: <87a5hxfs3d.fsf@draig.linaro.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-2-seanjc@google.com> <87a5hxfs3d.fsf@draig.linaro.org> Message-ID: Subject: Re: [PATCH v12 01/84] KVM: arm64: Release pfn, i.e. put page, if copying MTE tags hits ZONE_DEVICE From: Sean Christopherson To: "Alex =?utf-8?Q?Benn=C3=A9e?=" Cc: Paolo Bonzini , Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Wed, Jul 31, 2024, Alex Benn=C3=A9e wrote: > Sean Christopherson writes: >=20 > > Put the page reference acquired by gfn_to_pfn_prot() if > > kvm_vm_ioctl_mte_copy_tags() runs into ZONE_DEVICE memory. KVM's less- > > than-stellar heuristics for dealing with pfn-mapped memory means that K= VM > > can get a page reference to ZONE_DEVICE memory. > > > > Fixes: f0376edb1ddc ("KVM: arm64: Add ioctl to fetch/store tags in a gu= est") > > Signed-off-by: Sean Christopherson > > --- > > arch/arm64/kvm/guest.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > > index 11098eb7eb44..e1f0ff08836a 100644 > > --- a/arch/arm64/kvm/guest.c > > +++ b/arch/arm64/kvm/guest.c > > @@ -1059,6 +1059,7 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, > > page =3D pfn_to_online_page(pfn); > > if (!page) { > > /* Reject ZONE_DEVICE memory */ > > + kvm_release_pfn_clean(pfn); >=20 > I guess this gets renamed later in the series. >=20 > However my main comment is does lack of page always mean a ZONE_DEVICE? Nope. > Looking at pfn_to_online_page() I see a bunch of other checks first. Why > isn't it that functions responsibility to clean up after itself if its > returning NULLs? pfn_to_online_page() is more strict than gfn_to_pfn_prot(). At least in th= eory, gfn_to_pfn_prot() could return a pfn that has an associated "struct page", = with a reference held to said page. But for that same pfn, pfn_to_online_page()= could return NULL, in which case KVM needs to put the reference it acquired via gfn_to_pfn_prot(). 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CA052C3DA64 for ; Wed, 31 Jul 2024 20:36:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID: References:Mime-Version:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=YtSGqVfbRQcxAeGRNeLFo2gfReFJ1wYQjk8bw7TDmYg=; b=f95ocdBpDJShCCRAhhHUizQ89v cOZ9TKW35h9tyTHBjsw7c8alJYJj3sRYqPSfLAcqUEjJ01DymUFVPhaMJYPBSMMHAapmYIpdDkJcy MDOxH/UvZF2feg77kmG3LYAHn8+ujn7cqomOeVBwEQDnmgZrnTvcWLjeFytKTBzsrhhUcIjUsb6G+ Mr4D0zvkXCLzm4FGvKtwnyg21zx1knT7Guud9BZbjrdHGAJGxcVy0/GVwDxAWuWmq7qwtKl/XxhZ+ JsGj5xy5WFm1BZtu+k0nKz31GLEdjHWqAzbjBoPiJ+D3YvokwpBr8g+vt+4Ud3pvUpg7GkiS9LO10 qlnq9oFA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sZG3k-00000002TF9-0tsY; Wed, 31 Jul 2024 20:36:32 +0000 Received: from mail-yb1-xb4a.google.com ([2607:f8b0:4864:20::b4a]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sZG3g-00000002TDn-2Mb5 for linux-riscv@lists.infradead.org; Wed, 31 Jul 2024 20:36:30 +0000 Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-e0bcd04741fso172439276.2 for ; Wed, 31 Jul 2024 13:36:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1722458186; x=1723062986; darn=lists.infradead.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=Kd/mYHbPzOSIwsUM5m5UMPqJkKyWoklOLcVSOqbILGs=; b=gLFhZvKzhuC7jLD0Nm8gx1QWe7heoXLaGvRTR/j/wCY8+QtpqyYOjR8USq1pkjM626 Bgmhl3mAOvA2HFv1M5W+9lp59AKj1h8Q1VvAomgzaHXYA30pwo8TAQ5ewzcH3ge24dRm TJCPMaR1ck9siWrTjzZdREsoBq1WR50sh8V/TsfVp6gA8n3mOO3XALiUa4cW5L7S3ic3 UNg5jfYS2C4PbxqEYzD8d5uCWK5Hh7KKQ1DGFrUMwI5WlxzJ6SthjrcWnUzaa6+q1bvp OMg5S+/cAjuNTYUuDnmbnA0AcP7JPcb6ka9Shqb7oXVukTArK/08AkWKVEj+b+gPNi/C wJ+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722458186; x=1723062986; h=content-transfer-encoding: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=Kd/mYHbPzOSIwsUM5m5UMPqJkKyWoklOLcVSOqbILGs=; b=heP9ElRNWY8pm8Hy5qmKp0hCKyzheY21K7aQddhBkg+v0lEUMRuhqVod9WPPrrJ0ru Dc2z1qRyFxS07LkCDyoKqWc/8O+deYbmFx+bSpmQRrt/qxM3JZ7Ad01yz7Xrt0eFx1Zz FGYqFpoo/uXJ2hjBi34nh+yaGG4uDXyV1QvSsBYZWlbtH/2NDYQrYFsIot81Fpg2MP/v GMFMFCwzPELWiZSe0nKQpSaPGkx0n7HtsARFi9f2E+aPDPU/7u2rFILXtihFEIz7J/RZ q/WtQ9BGK6CjNoO4jJh4HheewzMEatGXVKTqtvYwRhrssiIB26sfUXq1sfNivCRznBcZ yTqw== X-Forwarded-Encrypted: i=1; AJvYcCXnav9gjEk50OcZBBQGX/+u5QyYsSsBZRwhUppNqZQr4srmpS+YbdihBT7jN9nKjYI4XpKRVZ2sZcyzDXOuj/tIvQHudJKv8at1zVMk4Fna X-Gm-Message-State: AOJu0Yy5bYUfNXfkPai/h0dku+6bubgHwWzqy0yQkldQ32YjL3fXW+e7 NAVBJ12lcBAAZeJU31HApUuh6A0qUjba9R1Zou2oQFB2Ep6TkZ7Tf5A2colC1wpQALHUZH3OeyY D0Q== X-Google-Smtp-Source: AGHT+IH0DRpeCdEjd5+EVXte2iiNPB7q7dTvECq86U0Z8nMo4fguKYduL9RXt42ZsXAM2SH8mq6gA4JZJ0k= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:18d2:b0:e0b:bf20:4ff8 with SMTP id 3f1490d57ef6-e0bccf7b434mr932276.0.1722458186501; Wed, 31 Jul 2024 13:36:26 -0700 (PDT) Date: Wed, 31 Jul 2024 13:36:25 -0700 In-Reply-To: <87a5hxfs3d.fsf@draig.linaro.org> Mime-Version: 1.0 References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-2-seanjc@google.com> <87a5hxfs3d.fsf@draig.linaro.org> Message-ID: Subject: Re: [PATCH v12 01/84] KVM: arm64: Release pfn, i.e. put page, if copying MTE tags hits ZONE_DEVICE From: Sean Christopherson To: "Alex =?utf-8?Q?Benn=C3=A9e?=" Cc: Paolo Bonzini , Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240731_133628_629598_65415DD2 X-CRM114-Status: GOOD ( 17.32 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org T24gV2VkLCBKdWwgMzEsIDIwMjQsIEFsZXggQmVubsOpZSB3cm90ZToKPiBTZWFuIENocmlzdG9w aGVyc29uIDxzZWFuamNAZ29vZ2xlLmNvbT4gd3JpdGVzOgo+IAo+ID4gUHV0IHRoZSBwYWdlIHJl ZmVyZW5jZSBhY3F1aXJlZCBieSBnZm5fdG9fcGZuX3Byb3QoKSBpZgo+ID4ga3ZtX3ZtX2lvY3Rs X210ZV9jb3B5X3RhZ3MoKSBydW5zIGludG8gWk9ORV9ERVZJQ0UgbWVtb3J5LiAgS1ZNJ3MgbGVz cy0KPiA+IHRoYW4tc3RlbGxhciBoZXVyaXN0aWNzIGZvciBkZWFsaW5nIHdpdGggcGZuLW1hcHBl ZCBtZW1vcnkgbWVhbnMgdGhhdCBLVk0KPiA+IGNhbiBnZXQgYSBwYWdlIHJlZmVyZW5jZSB0byBa T05FX0RFVklDRSBtZW1vcnkuCj4gPgo+ID4gRml4ZXM6IGYwMzc2ZWRiMWRkYyAoIktWTTogYXJt NjQ6IEFkZCBpb2N0bCB0byBmZXRjaC9zdG9yZSB0YWdzIGluIGEgZ3Vlc3QiKQo+ID4gU2lnbmVk LW9mZi1ieTogU2VhbiBDaHJpc3RvcGhlcnNvbiA8c2VhbmpjQGdvb2dsZS5jb20+Cj4gPiAtLS0K PiA+ICBhcmNoL2FybTY0L2t2bS9ndWVzdC5jIHwgMSArCj4gPiAgMSBmaWxlIGNoYW5nZWQsIDEg aW5zZXJ0aW9uKCspCj4gPgo+ID4gZGlmZiAtLWdpdCBhL2FyY2gvYXJtNjQva3ZtL2d1ZXN0LmMg Yi9hcmNoL2FybTY0L2t2bS9ndWVzdC5jCj4gPiBpbmRleCAxMTA5OGViN2ViNDQuLmUxZjBmZjA4 ODM2YSAxMDA2NDQKPiA+IC0tLSBhL2FyY2gvYXJtNjQva3ZtL2d1ZXN0LmMKPiA+ICsrKyBiL2Fy Y2gvYXJtNjQva3ZtL2d1ZXN0LmMKPiA+IEBAIC0xMDU5LDYgKzEwNTksNyBAQCBpbnQga3ZtX3Zt X2lvY3RsX210ZV9jb3B5X3RhZ3Moc3RydWN0IGt2bSAqa3ZtLAo+ID4gIAkJcGFnZSA9IHBmbl90 b19vbmxpbmVfcGFnZShwZm4pOwo+ID4gIAkJaWYgKCFwYWdlKSB7Cj4gPiAgCQkJLyogUmVqZWN0 IFpPTkVfREVWSUNFIG1lbW9yeSAqLwo+ID4gKwkJCWt2bV9yZWxlYXNlX3Bmbl9jbGVhbihwZm4p Owo+IAo+IEkgZ3Vlc3MgdGhpcyBnZXRzIHJlbmFtZWQgbGF0ZXIgaW4gdGhlIHNlcmllcy4KPiAK PiBIb3dldmVyIG15IG1haW4gY29tbWVudCBpcyBkb2VzIGxhY2sgb2YgcGFnZSBhbHdheXMgbWVh biBhIFpPTkVfREVWSUNFPwoKTm9wZS4KCj4gTG9va2luZyBhdCBwZm5fdG9fb25saW5lX3BhZ2Uo KSBJIHNlZSBhIGJ1bmNoIG9mIG90aGVyIGNoZWNrcyBmaXJzdC4gV2h5Cj4gaXNuJ3QgaXQgdGhh dCBmdW5jdGlvbnMgcmVzcG9uc2liaWxpdHkgdG8gY2xlYW4gdXAgYWZ0ZXIgaXRzZWxmIGlmIGl0 cwo+IHJldHVybmluZyBOVUxMcz8KCnBmbl90b19vbmxpbmVfcGFnZSgpIGlzIG1vcmUgc3RyaWN0 IHRoYW4gZ2ZuX3RvX3Bmbl9wcm90KCkuICBBdCBsZWFzdCBpbiB0aGVvcnksCmdmbl90b19wZm5f cHJvdCgpIGNvdWxkIHJldHVybiBhIHBmbiB0aGF0IGhhcyBhbiBhc3NvY2lhdGVkICJzdHJ1Y3Qg cGFnZSIsIHdpdGgKYSByZWZlcmVuY2UgaGVsZCB0byBzYWlkIHBhZ2UuICBCdXQgZm9yIHRoYXQg c2FtZSBwZm4sIHBmbl90b19vbmxpbmVfcGFnZSgpIGNvdWxkCnJldHVybiBOVUxMLCBpbiB3aGlj aCBjYXNlIEtWTSBuZWVkcyB0byBwdXQgdGhlIHJlZmVyZW5jZSBpdCBhY3F1aXJlZCB2aWEKZ2Zu X3RvX3Bmbl9wcm90KCkuCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fXwpsaW51eC1yaXNjdiBtYWlsaW5nIGxpc3QKbGludXgtcmlzY3ZAbGlzdHMuaW5mcmFk ZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4 LXJpc2N2Cg== 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1553CC3DA7F for ; Wed, 31 Jul 2024 20:37:16 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=4jLn21E+; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WZ3mp5D64z3dJ5 for ; Thu, 1 Aug 2024 06:37:14 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=4jLn21E+; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=flex--seanjc.bounces.google.com (client-ip=2607:f8b0:4864:20::b49; helo=mail-yb1-xb49.google.com; envelope-from=3sqcqzgykdhehtpcyrvddvat.rdbaxcjmeer-stkaxhih.doapqh.dgv@flex--seanjc.bounces.google.com; receiver=lists.ozlabs.org) Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4WZ3lz6qQCz2y8l for ; Thu, 1 Aug 2024 06:36:30 +1000 (AEST) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-e0bcd04741fso172454276.2 for ; Wed, 31 Jul 2024 13:36:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1722458187; x=1723062987; darn=lists.ozlabs.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=Kd/mYHbPzOSIwsUM5m5UMPqJkKyWoklOLcVSOqbILGs=; b=4jLn21E+uAcuSpX9OSfvwTSvSthWx1dA74H2cHqmX4nceketzG7VIGKc2u8vgEBSxX zkCnVIsJceWLqLUbjdu8MCO8tg8iPvsHVNiD0gnf/JLv24QP/RL9179ym2Mf+6C1/YJO ifUdXsOSNodsTHGY1MHJxSqgiP8A7yrh1tRIRgUZ3KBj56PAua/87gwi0/tYA9WF8G0X q8aLR1ojZVZkQFj7eGmoA5qEkjWVRFW3cxARJM9Xh0yUAff5Vin8q1J3iwQ1+Nf0QecQ hxzCdDZnMikulCBflHiCw7NF/RFuze3qhAn2LEtbw6LeQtAPOQxEy0QIqnYdUCN8RUew AOug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722458187; x=1723062987; h=content-transfer-encoding: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=Kd/mYHbPzOSIwsUM5m5UMPqJkKyWoklOLcVSOqbILGs=; b=wmzUmPl9KVw0fqPAI3rgZYesBHNhGYyNQeipUz4v54bLgc5COyri8NXbzLbZQwIc/P IgxcfwA0LkU5+nVrxCuOLpQTJTtgubMFcg4kdyJJCqfjg2wXcDB7sV8IsvxoeLxxPiit dmmWc+nORaIUVj8ZJEtOMG9WKDw+PI1EQg05m3pEI3d5BGO3qTFkZ2djLUWEIkMGR0sR 4jzyk1Qscvf5XaH0GLqWcmpNyhe7MNA1tD5XFLIZNq0dfBsMrtPDdQ7WlY8ICfeUURB5 q/iM+KliZO+Rrw/sOHuR7VK59YtaxoNAv9iJeaJIGnw1DkZn1YCBr853mYmO0rOvXEdB 3uQQ== X-Forwarded-Encrypted: i=1; AJvYcCUDZZr7IqMay8B9gIXFWlk2zq0Utv5F+OxTh76porW/quKRjlneAuxa2IouKvEARd1UCatYkycMNl+pZV/1zEDpQWCoZslHGa6YPh2rMA== X-Gm-Message-State: AOJu0YyazS1+CRtz9fe8sOHdclTwSCpiWF62wr7mg5rKG1S3HJSvSBBJ fAqI0M9sEWn6Iqpa33ABCry3syXFRDBVAFtZQNfQnSHPRj7wX0v/yMmS9qdJgqRf1vksM4bmKGk fgw== X-Google-Smtp-Source: AGHT+IH0DRpeCdEjd5+EVXte2iiNPB7q7dTvECq86U0Z8nMo4fguKYduL9RXt42ZsXAM2SH8mq6gA4JZJ0k= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:18d2:b0:e0b:bf20:4ff8 with SMTP id 3f1490d57ef6-e0bccf7b434mr932276.0.1722458186501; Wed, 31 Jul 2024 13:36:26 -0700 (PDT) Date: Wed, 31 Jul 2024 13:36:25 -0700 In-Reply-To: <87a5hxfs3d.fsf@draig.linaro.org> Mime-Version: 1.0 References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-2-seanjc@google.com> <87a5hxfs3d.fsf@draig.linaro.org> Message-ID: Subject: Re: [PATCH v12 01/84] KVM: arm64: Release pfn, i.e. put page, if copying MTE tags hits ZONE_DEVICE From: Sean Christopherson To: "Alex =?utf-8?Q?Benn=C3=A9e?=" Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Matlack , linux-riscv@lists.infradead.org, Claudio Imbrenda , Janosch Frank , Marc Zyngier , Huacai Chen , Christian Borntraeger , Albert Ou , Bibo Mao , loongarch@lists.linux.dev, Paul Walmsley , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, Oliver Upton , Palmer Dabbelt , David Stevens , kvm-riscv@lists.infradead.org, Anup Patel , Paolo Bonzini , Tianrui Zhao , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Jul 31, 2024, Alex Benn=C3=A9e wrote: > Sean Christopherson writes: >=20 > > Put the page reference acquired by gfn_to_pfn_prot() if > > kvm_vm_ioctl_mte_copy_tags() runs into ZONE_DEVICE memory. KVM's less- > > than-stellar heuristics for dealing with pfn-mapped memory means that K= VM > > can get a page reference to ZONE_DEVICE memory. > > > > Fixes: f0376edb1ddc ("KVM: arm64: Add ioctl to fetch/store tags in a gu= est") > > Signed-off-by: Sean Christopherson > > --- > > arch/arm64/kvm/guest.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > > index 11098eb7eb44..e1f0ff08836a 100644 > > --- a/arch/arm64/kvm/guest.c > > +++ b/arch/arm64/kvm/guest.c > > @@ -1059,6 +1059,7 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, > > page =3D pfn_to_online_page(pfn); > > if (!page) { > > /* Reject ZONE_DEVICE memory */ > > + kvm_release_pfn_clean(pfn); >=20 > I guess this gets renamed later in the series. >=20 > However my main comment is does lack of page always mean a ZONE_DEVICE? Nope. > Looking at pfn_to_online_page() I see a bunch of other checks first. Why > isn't it that functions responsibility to clean up after itself if its > returning NULLs? pfn_to_online_page() is more strict than gfn_to_pfn_prot(). At least in th= eory, gfn_to_pfn_prot() could return a pfn that has an associated "struct page", = with a reference held to said page. But for that same pfn, pfn_to_online_page()= could return NULL, in which case KVM needs to put the reference it acquired via gfn_to_pfn_prot().