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Mon, 17 Aug 2026 15:50:36 +0000 (UTC) Received: from [100.90.56.12] (headnet05.pony-001.prod.iad2.dc.redhat.com [10.2.32.117]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 2513C1956042; Mon, 17 Aug 2026 15:50:31 +0000 (UTC) Message-ID: <0143f26e-eb64-4924-8e76-3b6ce66fe6db@redhat.com> Date: Mon, 17 Aug 2026 17:50:30 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 08/16] cpus: Slightly improve *run_on_cpu() docstrings To: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org Cc: Daniel Henrique Barboza , Pierrick Bouvier , Mohamed Mediouni , Alexander Graf , qemu-ppc@nongnu.org, qemu-riscv@nongnu.org, kvm@vger.kernel.org, Richard Henderson , qemu-arm@nongnu.org, Magnus Kulke , Peter Maydell , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Zhao Liu References: <20260813181640.6537-1-philmd@oss.qualcomm.com> <20260813181640.6537-9-philmd@oss.qualcomm.com> From: Paolo Bonzini 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: <20260813181640.6537-9-philmd@oss.qualcomm.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: Cpw740KX-kVlzkHujG1VElRXmW-2YPd2J3phR1trDJM_1786981837 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.343, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-arm@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-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org Sender: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org On 8/13/26 20:16, Philippe Mathieu-Daudé wrote: > Be a bit more precise mentioning BQL use and blocking calls. > > Signed-off-by: Philippe Mathieu-Daudé > --- > include/hw/core/cpu.h | 36 ++++++++++++++++++++---------------- > 1 file changed, 20 insertions(+), 16 deletions(-) > > diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h > index 183ef9f4ef2..d610f87abd3 100644 > --- a/include/hw/core/cpu.h > +++ b/include/hw/core/cpu.h > @@ -908,36 +908,40 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data, > QemuMutex *mutex); > > /** > - * run_on_cpu: > + * run_on_cpu - Execute a function on a vCPU and wait for completion > * @cpu: The vCPU to run on. > * @func: The function to be executed. > * @data: Data to pass to the function. > * > - * Schedules the function @func for execution on the vCPU @cpu. > + * Schedules the function @func for execution on the vCPU @cpu and > + * block until it completes. > + * > + * Note: The caller must hold the BQL. > */ > void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data); > > /** > - * async_run_on_cpu: > - * @cpu: The vCPU to run on. > - * @func: The function to be executed. > - * @data: Data to pass to the function. > - * > - * Schedules the function @func for execution on the vCPU @cpu asynchronously. > - */ > -void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data); > - > -/** > - * async_safe_run_on_cpu: > + * async_run_on_cpu - Queue a function for execution on a vCPU > * @cpu: The vCPU to run on. > * @func: The function to be executed. > * @data: Data to pass to the function. > * > * Schedules the function @func for execution on the vCPU @cpu asynchronously, > - * while all other vCPUs are sleeping. > + * then return immediately without waiting. > * > - * Unlike run_on_cpu and async_run_on_cpu, the function is run outside the > - * BQL. > + * Note: The vCPU will hold the BQL when executing @func. > + */ > +void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data); > + > +/** > + * async_safe_run_on_cpu - Queue a function to run with other vCPUs paused > + * @cpu: The vCPU to run on. > + * @func: The function to be executed. > + * @data: Data to pass to the function. > + * > + * Schedules the function @func for execution on the vCPU @cpu asynchronously. > + * Unlike async_run_on_cpu(), all other vCPUs are paused while @func executes, > + * ensuring @cpu has exclusive access to shared state. Might as well mention that @func is run without the BQL taken and in fact must not take it (see comment in process_queued_cpu_work()). Paolo > */ > void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data); >