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Tsirkin" , Manos Pitsidianakis , Junjie Mao , =?UTF-8?Q?Alex_Benn=C3=A9e?= , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Peter Maydell Cc: qemu-devel@nongnu.org, qemu-rust@nongnu.org References: <20241205060714.256270-1-zhao1.liu@intel.com> <20241205060714.256270-4-zhao1.liu@intel.com> From: Paolo Bonzini Content-Language: en-US Autocrypt: addr=pbonzini@redhat.com; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0j UGFvbG8gQm9uemluaSA8cGJvbnppbmlAcmVkaGF0LmNvbT7CwU0EEwECACMFAlRCcBICGwMH CwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAAKCRB+FRAMzTZpsbceDp9IIN6BIA0Ol7MoB15E 11kRz/ewzryFY54tQlMnd4xxfH8MTQ/mm9I482YoSwPMdcWFAKnUX6Yo30tbLiNB8hzaHeRj jx12K+ptqYbg+cevgOtbLAlL9kNgLLcsGqC2829jBCUTVeMSZDrzS97ole/YEez2qFpPnTV0 VrRWClWVfYh+JfzpXmgyhbkuwUxNFk421s4Ajp3d8nPPFUGgBG5HOxzkAm7xb1cjAuJ+oi/K CHfkuN+fLZl/u3E/fw7vvOESApLU5o0icVXeakfSz0LsygEnekDbxPnE5af/9FEkXJD5EoYG SEahaEtgNrR4qsyxyAGYgZlS70vkSSYJ+iT2rrwEiDlo31MzRo6Ba2FfHBSJ7lcYdPT7bbk9 AO3hlNMhNdUhoQv7M5HsnqZ6unvSHOKmReNaS9egAGdRN0/GPDWr9wroyJ65ZNQsHl9nXBqE AukZNr5oJO5vxrYiAuuTSd6UI/xFkjtkzltG3mw5ao2bBpk/V/YuePrJsnPFHG7NhizrxttB nTuOSCMo45pfHQ+XYd5K1+Cv/NzZFNWscm5htJ0HznY+oOsZvHTyGz3v91pn51dkRYN0otqr bQ4tlFFuVjArBZcapSIe6NV8C4cEiSTOwE0EVEJx7gEIAMeHcVzuv2bp9HlWDp6+RkZe+vtl KwAHplb/WH59j2wyG8V6i33+6MlSSJMOFnYUCCL77bucx9uImI5nX24PIlqT+zasVEEVGSRF m8dgkcJDB7Tps0IkNrUi4yof3B3shR+vMY3i3Ip0e41zKx0CvlAhMOo6otaHmcxr35sWq1Jk tLkbn3wG+fPQCVudJJECvVQ//UAthSSEklA50QtD2sBkmQ14ZryEyTHQ+E42K3j2IUmOLriF dNr9NvE1QGmGyIcbw2NIVEBOK/GWxkS5+dmxM2iD4Jdaf2nSn3jlHjEXoPwpMs0KZsgdU0pP JQzMUMwmB1wM8JxovFlPYrhNT9MAEQEAAcLBMwQYAQIACQUCVEJx7gIbDAAKCRB+FRAMzTZp sadRDqCctLmYICZu4GSnie4lKXl+HqlLanpVMOoFNnWs9oRP47MbE2wv8OaYh5pNR9VVgyhD OG0AU7oidG36OeUlrFDTfnPYYSF/mPCxHttosyt8O5kabxnIPv2URuAxDByz+iVbL+RjKaGM GDph56ZTswlx75nZVtIukqzLAQ5fa8OALSGum0cFi4ptZUOhDNz1onz61klD6z3MODi0sBZN Aj6guB2L/+2ZwElZEeRBERRd/uommlYuToAXfNRdUwrwl9gRMiA0WSyTb190zneRRDfpSK5d usXnM/O+kr3Dm+Ui+UioPf6wgbn3T0o6I5BhVhs4h4hWmIW7iNhPjX1iybXfmb1gAFfjtHfL xRUr64svXpyfJMScIQtBAm0ihWPltXkyITA92ngCmPdHa6M1hMh4RDX+Jf1fiWubzp1voAg0 JBrdmNZSQDz0iKmSrx8xkoXYfA3bgtFN8WJH2xgFL28XnqY4M6dLhJwV3z08tPSRqYFm4NMP dRsn0/7oymhneL8RthIvjDDQ5ktUjMe8LtHr70OZE/TT88qvEdhiIVUogHdo4qBrk41+gGQh b906Dudw5YhTJFU3nC6bbF2nrLlB4C/XSiH76ZvqzV0Z/cAMBo5NF/w= In-Reply-To: <20241205060714.256270-4-zhao1.liu@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 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=-0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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 12/5/24 07:07, Zhao Liu wrote: > The get_mut() is useful when doing compound assignment operations, e.g., > *c.get_mut() += 1. > > Implement get_mut() for BqlCell by referring to Cell. I think you can't do this because the BQL might be released while the owner has a &mut. Like: let mtx = Mutex>::new(); let guard = mtx.lock(); let cell = &mut *guard; let inner = cell.get_mut(cell); // anything that releases bql_lock *inner += 1; On the other hand I don't think you need it. You have just two uses. First, this one: + if set && self.is_int_level_triggered() { + // If Timer N Interrupt Enable bit is 0, "the timer will + // still operate and generate appropriate status bits, but + // will not cause an interrupt" + *self.get_state_mut().int_status.get_mut() |= mask; + } else { + *self.get_state_mut().int_status.get_mut() &= !mask; + } Where you can just write self.get_state_ref().update_int_status(self.index, set && self.is_int_level_triggered()) and the HPETState can do something like fn update_int_status(&self, index: u32, level: bool) { self.int_status.set(deposit64(self.int_status.get(), bit, 1, level as u64)); } For hpet_fw_cfg you have unsafe in the device and it's better if you do: - self.hpet_id.set(unsafe { hpet_fw_cfg.assign_hpet_id() }); + self.hpet_id.set(fw_cfg_config::assign_hpet_id()); with methods like this that do the unsafe access: impl fw_cfg_config { pub(crate) fn assign_hpet_id() -> usize { assert!(bql_locked()); // SAFETY: all accesses go through these methods, which guarantee // that the accesses are protected by the BQL. let fw_cfg = unsafe { &mut *hpet_fw_cfg }; if self.count == u8::MAX { // first instance fw_cfg.count = 0; } if fw_cfg.count == 8 { // TODO: Add error binding: error_setg() panic!("Only 8 instances of HPET is allowed"); } let id: usize = fw_cfg.count.into(); fw_cfg.count += 1; id } } and you can assert bql_locked by hand instead of using the BqlCell. Paolo > Signed-off-by: Zhao Liu > --- > rust/qemu-api/src/cell.rs | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/rust/qemu-api/src/cell.rs b/rust/qemu-api/src/cell.rs > index 07b636f26266..95f1cc0b3eb5 100644 > --- a/rust/qemu-api/src/cell.rs > +++ b/rust/qemu-api/src/cell.rs > @@ -324,6 +324,31 @@ impl BqlCell { > pub const fn as_ptr(&self) -> *mut T { > self.value.get() > } > + > + /// Returns a mutable reference to the underlying data. > + /// > + /// This call borrows `BqlCell` mutably (at compile-time) which guarantees > + /// that we possess the only reference. > + /// > + /// However be cautious: this method expects `self` to be mutable, which is > + /// generally not the case when using a `BqlCell`. If you require interior > + /// mutability by reference, consider using `BqlRefCell` which provides > + /// run-time checked mutable borrows through its [`borrow_mut`] method. > + /// > + /// [`borrow_mut`]: BqlRefCell::borrow_mut() > + /// > + /// # Examples > + /// > + /// ``` > + /// use qemu_api::cell::BqlCell;; > + /// > + /// let mut c = BqlCell::new(5); > + /// *c.get_mut() += 1; > + /// > + /// assert_eq!(c.get(), 6); > + pub fn get_mut(&mut self) -> &mut T { > + self.value.get_mut() > + } > } > > impl BqlCell {