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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3912bfdfe61sm17731252f8f.38.2025.03.11.01.54.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 11 Mar 2025 01:54:46 -0700 (PDT) Message-ID: <37026d8c-e892-47cc-b2b1-21d36fe856c2@linaro.org> Date: Tue, 11 Mar 2025 09:54:44 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 09/21] hw/vfio/pci: Convert CONFIG_KVM check to runtime one To: BALATON Zoltan , Eric Auger Cc: qemu-devel@nongnu.org, Yi Liu , Pierrick Bouvier , Alex Williamson , Christian Borntraeger , =?UTF-8?Q?Alex_Benn=C3=A9e?= , Tony Krowiak , Nicholas Piggin , Halil Pasic , Thomas Huth , David Hildenbrand , Igor Mammedov , Matthew Rosato , Tomita Moeko , qemu-ppc@nongnu.org, Daniel Henrique Barboza , Eric Farman , Eduardo Habkost , Peter Xu , kvm@vger.kernel.org, Zhenzhong Duan , qemu-s390x@nongnu.org, Paolo Bonzini , Harsh Prateek Bora , =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , Ilya Leoshkevich , Jason Herne , =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Richard Henderson References: <20250308230917.18907-1-philmd@linaro.org> <20250308230917.18907-10-philmd@linaro.org> <28c102c1-d157-4d22-a351-9fcc8f4260fd@redhat.com> <2d44848e-01c1-25c5-dfcb-99f5112fcbd7@eik.bme.hu> Content-Language: en-US From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: <2d44848e-01c1-25c5-dfcb-99f5112fcbd7@eik.bme.hu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::334; envelope-from=philmd@linaro.org; helo=mail-wm1-x334.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, T_SPF_TEMPERROR=0.01 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 10/3/25 13:54, BALATON Zoltan wrote: > On Mon, 10 Mar 2025, Eric Auger wrote: >> Hi Philippe, >> >> On 3/9/25 12:09 AM, Philippe Mathieu-Daudé wrote: >>> Use the runtime kvm_enabled() helper to check whether >>> KVM is available or not. >> >> Miss the "why" of this patch. >> >> By the way I fail to remember/see where kvm_allowed is set. In accel/accel-system.c: int accel_init_machine(AccelState *accel, MachineState *ms) { AccelClass *acc = ACCEL_GET_CLASS(accel); int ret; ms->accelerator = accel; *(acc->allowed) = true; ret = acc->init_machine(ms); if (ret < 0) { ms->accelerator = NULL; *(acc->allowed) = false; object_unref(OBJECT(accel)); } else { object_set_accelerator_compat_props(acc->compat_props); } return ret; } > > It's in include/system/kvm.h > >> I am also confused because we still have some code, like in >> vfio/common.c which does both checks: >> #ifdef CONFIG_KVM >>         if (kvm_enabled()) { >>             max_memslots = kvm_get_max_memslots(); >>         } >> #endif We should prefer kvm_enabled() over CONFIG_KVM, but for kvm_enabled() we need the prototypes declared, which sometimes aren't.