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AJvYcCVwpNVVbCOzZdNqRVDYCxGk94pv8RrKzZ9QadBW++bBKzG8vc7lAoK2VyAx4z6f7o/ADEjnph10QOWWsyzPVj5WbWTjlJb1Z4Jicg== X-Gm-Message-State: AOJu0Yz1o2Wi5vbDBZdnihiveRcdx7/O5ycBtjABosbTeYxwOGQiGRQd VC4vgSfn4wqJ8rnjfLPyXygzK0hk7JRsmg3lzBSLA1ibidm7DjIHCWAFns0QCc4= X-Google-Smtp-Source: AGHT+IFaeuLsqXvHIvwNkMOmXQ/kk95KnaHAVzfZZFY2rJSwrdZANzuSfUeE19U50MBeGB1J/TbUHg== X-Received: by 2002:a17:907:a0d5:b0:a7a:b070:92c6 with SMTP id a640c23a62f3a-a7d40116a4bmr801926666b.50.1722443015967; Wed, 31 Jul 2024 09:23:35 -0700 (PDT) Received: from draig.lan ([85.9.250.243]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a7acad416basm784769266b.104.2024.07.31.09.23.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Jul 2024 09:23:35 -0700 (PDT) Received: from draig (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id 614DC5F8CB; Wed, 31 Jul 2024 17:23:34 +0100 (BST) From: =?utf-8?Q?Alex_Benn=C3=A9e?= To: Sean Christopherson 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 Subject: Re: [PATCH v12 01/84] KVM: arm64: Release pfn, i.e. put page, if copying MTE tags hits ZONE_DEVICE In-Reply-To: <20240726235234.228822-2-seanjc@google.com> (Sean Christopherson's message of "Fri, 26 Jul 2024 16:51:10 -0700") References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-2-seanjc@google.com> Date: Wed, 31 Jul 2024 17:23:34 +0100 Message-ID: <87a5hxfs3d.fsf@draig.linaro.org> Precedence: bulk X-Mailing-List: linux-mips@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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 gues= t") > 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); I guess this gets renamed later in the series. However my main comment is does lack of page always mean a ZONE_DEVICE? 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? > ret =3D -EFAULT; > goto out; > } --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro