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Mon, 11 Aug 2025 07:49:14 -0700 (PDT) Received: from draig.lan ([185.126.160.19]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-459e0cd2c90sm306189205e9.17.2025.08.11.07.49.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Aug 2025 07:49:13 -0700 (PDT) Received: from draig (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id B9AF75F834; Mon, 11 Aug 2025 15:49:12 +0100 (BST) From: =?utf-8?Q?Alex_Benn=C3=A9e?= To: Paolo Bonzini Cc: qemu-devel@nongnu.org, imammedo@redhat.com, richard.henderson@linaro.org, peterx@redhat.com Subject: Re: [PATCH 3/8] accel: use atomic accesses for exit_request In-Reply-To: <20250808185905.62776-4-pbonzini@redhat.com> (Paolo Bonzini's message of "Fri, 8 Aug 2025 20:59:00 +0200") References: <20250808185905.62776-1-pbonzini@redhat.com> <20250808185905.62776-4-pbonzini@redhat.com> User-Agent: mu4e 1.12.12; emacs 30.1 Date: Mon, 11 Aug 2025 15:49:12 +0100 Message-ID: <87zfc5c3rr.fsf@draig.linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::32e; envelope-from=alex.bennee@linaro.org; helo=mail-wm1-x32e.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 Paolo Bonzini writes: > CPU threads write exit_request as a "note to self" that they need to > go out to a slow path. This write happens out of the BQL and can be > a data race with another threads' cpu_exit(); use atomic accesses > consistently. > > Signed-off-by: Paolo Bonzini > --- > accel/tcg/tcg-accel-ops-mttcg.c | 2 +- > accel/tcg/tcg-accel-ops-rr.c | 4 ++-- > hw/ppc/spapr_hcall.c | 6 +++--- > target/i386/kvm/kvm.c | 2 +- > target/i386/nvmm/nvmm-accel-ops.c | 2 +- > target/i386/nvmm/nvmm-all.c | 2 +- > target/i386/whpx/whpx-all.c | 6 +++--- > 7 files changed, 12 insertions(+), 12 deletions(-) Could you please update include/hw/core/cpu.h with a doc patch to describe exit_request and note it should be read/written with qatomic primitives please. --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro