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Tsirkin" , linux-kernel@vger.kernel.org Cc: Jason Wang , Pankaj Gupta , virtualization@lists.linux-foundation.org, teawater References: <20200608061406.709211-1-mst@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <0930c9d0-0708-c079-29bd-b80d4e3ce446@redhat.com> Date: Mon, 8 Jun 2020 08:58:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200608061406.709211-1-mst@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.06.20 08:14, Michael S. Tsirkin wrote: > If subblock size is large (e.g. 1G) 32 bit math involving it > can overflow. Rather than try to catch all instances of that, > let's tweak block size to 64 bit. I fail to see where we could actually trigger an overflow. The reported warning looked like a false positive to me. > > It ripples through UAPI which is an ABI change, but it's not too late to > make it, and it will allow supporting >4Gbyte blocks while might > become necessary down the road. > This might break cloud-hypervisor, who's already implementing this protocol upstream (ccing Hui). https://github.com/cloud-hypervisor/cloud-hypervisor/blob/master/vm-virtio/src/mem.rs (blocks in the gigabyte range were never the original intention of virtio-mem, but I am not completely opposed to that) > Fixes: 5f1f79bbc9e26 ("virtio-mem: Paravirtualized memory hotplug") > Signed-off-by: Michael S. Tsirkin > --- > drivers/virtio/virtio_mem.c | 14 +++++++------- > include/uapi/linux/virtio_mem.h | 4 ++-- > 2 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c > index 2f357142ea5e..7b1bece8a331 100644 > --- a/drivers/virtio/virtio_mem.c > +++ b/drivers/virtio/virtio_mem.c > @@ -77,7 +77,7 @@ struct virtio_mem { > uint64_t requested_size; > > /* The device block size (for communicating with the device). */ > - uint32_t device_block_size; > + uint64_t device_block_size; > /* The translated node id. NUMA_NO_NODE in case not specified. */ > int nid; > /* Physical start address of the memory region. */ > @@ -86,7 +86,7 @@ struct virtio_mem { > uint64_t region_size; > > /* The subblock size. */ > - uint32_t subblock_size; > + uint64_t subblock_size; > /* The number of subblocks per memory block. */ > uint32_t nb_sb_per_mb; > > @@ -1698,9 +1698,9 @@ static int virtio_mem_init(struct virtio_mem *vm) > * - At least the device block size. > * In the worst case, a single subblock per memory block. > */ > - vm->subblock_size = PAGE_SIZE * 1u << max_t(uint32_t, MAX_ORDER - 1, > - pageblock_order); > - vm->subblock_size = max_t(uint32_t, vm->device_block_size, > + vm->subblock_size = PAGE_SIZE * 1ul << max_t(uint32_t, MAX_ORDER - 1, > + pageblock_order); > + vm->subblock_size = max_t(uint64_t, vm->device_block_size, > vm->subblock_size); > vm->nb_sb_per_mb = memory_block_size_bytes() / vm->subblock_size; > > @@ -1713,8 +1713,8 @@ static int virtio_mem_init(struct virtio_mem *vm) > > dev_info(&vm->vdev->dev, "start address: 0x%llx", vm->addr); > dev_info(&vm->vdev->dev, "region size: 0x%llx", vm->region_size); > - dev_info(&vm->vdev->dev, "device block size: 0x%x", > - vm->device_block_size); > + dev_info(&vm->vdev->dev, "device block size: 0x%llx", > + (unsigned long long)vm->device_block_size); > dev_info(&vm->vdev->dev, "memory block size: 0x%lx", > memory_block_size_bytes()); > dev_info(&vm->vdev->dev, "subblock size: 0x%x", > diff --git a/include/uapi/linux/virtio_mem.h b/include/uapi/linux/virtio_mem.h > index a455c488a995..a9ffe041843c 100644 > --- a/include/uapi/linux/virtio_mem.h > +++ b/include/uapi/linux/virtio_mem.h > @@ -185,10 +185,10 @@ struct virtio_mem_resp { > > struct virtio_mem_config { > /* Block size and alignment. Cannot change. */ > - __u32 block_size; > + __u64 block_size; > /* Valid with VIRTIO_MEM_F_ACPI_PXM. Cannot change. */ > __u16 node_id; > - __u16 padding; > + __u8 padding[6]; > /* Start address of the memory region. Cannot change. */ > __u64 addr; > /* Region size (maximum). Cannot change. */ > -- Thanks, David / dhildenb