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[122.150.204.179]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3276fce1160sm9213646a91.22.2025.08.29.14.56.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Aug 2025 14:56:54 -0700 (PDT) Message-ID: <743782b5-1e3b-4b63-afe2-4ad1da333bde@linaro.org> Date: Sat, 30 Aug 2025 07:56:50 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 14/18] cpus: properly kick CPUs out of inner execution loop To: Paolo Bonzini , qemu-devel@nongnu.org Cc: peterx@redhat.com, imammedo@redhat.com References: <20250829152909.1589668-1-pbonzini@redhat.com> <20250829153115.1590048-10-pbonzini@redhat.com> From: Richard Henderson Content-Language: en-US In-Reply-To: <20250829153115.1590048-10-pbonzini@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::102f; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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 8/30/25 01:31, Paolo Bonzini wrote: > @@ -624,8 +624,7 @@ static target_ulong h_confer(PowerPCCPU *cpu, SpaprMachineState *spapr, > } > > cs->exception_index = EXCP_YIELD; > - qatomic_set(&cs->exit_request, true); > - cpu_loop_exit(cs); > + cpu_exit(cs); > > return H_SUCCESS; > } cpu_loop_exit does a longjmp; cpu_exit does not. This may be a bug fix, but it's hard to tell. If it is a bug fix, it should be separated. I'm also having a hard time with e.g. > +++ b/system/cpu-timers.c > @@ -246,14 +246,14 @@ void qemu_timer_notify_cb(void *opaque, QEMUClockType type) > > if (qemu_in_vcpu_thread()) { > /* > - * A CPU is currently running; kick it back out to the > + * A CPU is currently running; kick it back out of the > * tcg_cpu_exec() loop so it will recalculate its > * icount deadline immediately. > */ > - qemu_cpu_kick(current_cpu); > + cpu_exit(current_cpu); where the comment still says kick and we're replacing kick with exit. I guess the root of this problem is that "kick" isn't a precise term, we ought to name it something else, and we should paint the bike shed green. r~