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[91.12.96.198]) by smtp.gmail.com with ESMTPSA id y15sm2342827wrw.64.2021.08.23.12.14.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Aug 2021 12:15:00 -0700 (PDT) Subject: Re: [PATCH v2 0/3] virtio-mem: disallow mapping virtio-mem memory via /dev/mem To: linux-kernel@vger.kernel.org Cc: Arnd Bergmann , Greg Kroah-Hartman , "Michael S. Tsirkin" , Jason Wang , "Rafael J. Wysocki" , Andrew Morton , Dan Williams , Hanjun Guo , Andy Shevchenko , virtualization@lists.linux-foundation.org, linux-mm@kvack.org References: <20210816142505.28359-1-david@redhat.com> From: David Hildenbrand Organization: Red Hat Message-ID: Date: Mon, 23 Aug 2021 21:14:59 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210816142505.28359-1-david@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=dh5eB2zK; spf=none (imf23.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Stat-Signature: ahzmkygenk5pc19c6cf18kxkpd8e85jo X-Rspamd-Queue-Id: 01D0790000A0 X-Rspamd-Server: rspam04 X-HE-Tag: 1629746105-399555 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: On 16.08.21 16:25, David Hildenbrand wrote: > Let's add the basic infrastructure to exclude some physical memory > regions completely from /dev/mem access, on any architecture and under > any system configuration (independent of CONFIG_STRICT_DEVMEM and > independent of "iomem="). > > Use it for virtio-mem, to disallow mapping any virtio-mem memory via > /dev/mem to user space after the virtio-mem driver was loaded: there is > no sane use case to access the device-managed memory region via /dev/mem > once the driver is actively (un)plugging memory within that region and > we want to make sure that nobody will accidentially access unplugged > memory in a sane environment. > > Details can be found in patch #1. > > v1 -> v2: > - "/dev/mem: disallow access to explicitly excluded system RAM regions" > -- Introduce and use for_each_resource() and next_resource_skip_children() > -- s/iomem_range_contains_excluded/iomem_range_contains_excluded_devmem/ > - "kernel/resource: cleanup and optimize iomem_is_exclusive()" > -- Use for_each_resource() > > Cc: Arnd Bergmann > Cc: Greg Kroah-Hartman > Cc: "Michael S. Tsirkin" > Cc: Jason Wang > Cc: "Rafael J. Wysocki" > Cc: Andrew Morton > Cc: Dan Williams > Cc: Hanjun Guo > Cc: Andy Shevchenko > Cc: virtualization@lists.linux-foundation.org > Cc: linux-mm@kvack.org > > David Hildenbrand (3): > /dev/mem: disallow access to explicitly excluded system RAM regions > virtio-mem: disallow mapping virtio-mem memory via /dev/mem > kernel/resource: cleanup and optimize iomem_is_exclusive() > > drivers/char/mem.c | 22 ++++++-------- > drivers/virtio/virtio_mem.c | 4 ++- > include/linux/ioport.h | 1 + > kernel/resource.c | 60 +++++++++++++++++++++++++++++++++---- > lib/Kconfig.debug | 4 ++- > 5 files changed, 71 insertions(+), 20 deletions(-) > > > base-commit: 7c60610d476766e128cc4284bb6349732cbd6606 > More review welcome; I'd suggest this should go via the -mm tree, and not via the vhost tree. -- Thanks, David / dhildenb