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[2003:cb:c70b:db00:724d:8b0c:110e:3713]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-438b31d99ffsm18427065e9.29.2025.01.22.02.18.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Jan 2025 02:18:30 -0800 (PST) Message-ID: Date: Wed, 22 Jan 2025 11:18:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/4] physmem: disallow direct access to RAM DEVICE in address_space_write_rom() To: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org Cc: Paolo Bonzini , Peter Xu , Peter Maydell , =?UTF-8?Q?Alex_Benn=C3=A9e?= , Alex Williamson , Eduardo Habkost , Marcel Apfelbaum , Elena Ufimtseva , Jagannathan Raman , "Dr. David Alan Gilbert" , Stefan Zabka References: <20250120111503.244994-1-david@redhat.com> <20250120111503.244994-2-david@redhat.com> <5267cc69-18ec-48b1-be60-90c972922806@linaro.org> <4df5272b-b1f6-4aec-a0ee-c3de324d8000@linaro.org> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <4df5272b-b1f6-4aec-a0ee-c3de324d8000@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -51 X-Spam_score: -5.2 X-Spam_bar: ----- X-Spam_report: (-5.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.996, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.086, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 22.01.25 11:17, Philippe Mathieu-Daudé wrote: > On 22/1/25 11:13, David Hildenbrand wrote: >> On 22.01.25 11:10, David Hildenbrand wrote: >>> On 22.01.25 11:07, Philippe Mathieu-Daudé wrote: >>>> Hi David, >>>> >>>> On 20/1/25 12:14, David Hildenbrand wrote: >>>>> As documented in commit 4a2e242bbb306 ("memory: Don't use memcpy for >>>>> ram_device regions"), we disallow direct access to RAM DEVICE regions. >>>>> >>>>> Let's factor out the "supports direct access" check from >>>>> memory_access_is_direct() so we can reuse it, and make it a bit >>>>> easier to >>>>> read. >>>>> >>>>> This change implies that address_space_write_rom() and >>>>> cpu_memory_rw_debug() won't be able to write to RAM DEVICE regions. It >>>>> will also affect cpu_flush_icache_range(), but it's only used by >>>>> hw/core/loader.c after writing to ROM, so it is expected to not apply >>>>> here with RAM DEVICE. >>>>> >>>>> This fixes direct access to these regions where we don't want direct >>>>> access. We'll extend cpu_memory_rw_debug() next to also be able to >>>>> write to >>>>> these (and IO) regions. >>>>> >>>>> This is a preparation for further changes. >>>>> >>>>> Cc: Alex Williamson >>>>> Signed-off-by: David Hildenbrand >>>>> --- >>>>>     include/exec/memory.h | 30 ++++++++++++++++++++++++------ >>>>>     system/physmem.c      |  3 +-- >>>>>     2 files changed, 25 insertions(+), 8 deletions(-) >>>>> >>>>> diff --git a/include/exec/memory.h b/include/exec/memory.h >>>>> index 3ee1901b52..bd0ddb9cdf 100644 >>>>> --- a/include/exec/memory.h >>>>> +++ b/include/exec/memory.h >>>>> @@ -2985,15 +2985,33 @@ MemTxResult >>>>> address_space_write_cached_slow(MemoryRegionCache *cache, >>>>>     int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr); >>>>>     bool prepare_mmio_access(MemoryRegion *mr); >>>>> +static inline bool >>>>> memory_region_supports_direct_access(MemoryRegion *mr) >>>>> +{ >>>>> +    /* ROM DEVICE regions only allow direct access if in ROMD mode. */ >>>>> +    if (memory_region_is_romd(mr)) { >>>>> +        return true; >>>>> +    } >>>>> +    if (!memory_region_is_ram(mr)) { >>>>> +        return false; >>>>> +    } >>>>> +    /* >>>>> +     * RAM DEVICE regions can be accessed directly using memcpy, >>>>> but it might >>>>> +     * be MMIO and access using mempy can be wrong (e.g., using >>>>> instructions not >>>>> +     * intended for MMIO access). So we treat this as IO. >>>>> +     */ >>>>> +    return !memory_region_is_ram_device(mr); >>>>> + >>>>> +} >>>>> + >>>>>     static inline bool memory_access_is_direct(MemoryRegion *mr, >>>>> bool is_write) >>>>>     { >>>>> -    if (is_write) { >>>>> -        return memory_region_is_ram(mr) && !mr->readonly && >>>>> -               !mr->rom_device && !memory_region_is_ram_device(mr); >>>>> -    } else { >>>>> -        return (memory_region_is_ram(mr) && ! >>>>> memory_region_is_ram_device(mr)) || >>>> >>>> This patch is doing multiple things at once, and I'm having hard time >>>> reviewing it. >>> >>> I appreciate the review, but ... really?! :) >>> >>> 25 insertions(+), 8 deletions(-) >> >> FWIW, I'll try to split it up ... I thought the comments added to >> memory_region_supports_direct_access() and friends are pretty clear. > > No worry, I'll give it another try. (split still welcomed, but not > blocking). I think unmangling the existing unreadable conditions in memory_access_is_direct() can be done separately; let me see what I can do. -- Cheers, David / dhildenb