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[109.43.177.165]) by smtp.gmail.com with ESMTPSA id m12-20020adff38c000000b003145559a691sm12402548wro.41.2023.07.24.02.53.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Jul 2023 02:53:41 -0700 (PDT) Message-ID: <81dd6b4c-200f-bb35-69fa-ed623eb7e6d1@redhat.com> Date: Mon, 24 Jul 2023 11:53:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH] kvm: Remove KVM_CREATE_IRQCHIP support assumption Content-Language: en-US To: Andrew Jones , qemu-devel@nongnu.org Cc: pbonzini@redhat.com, mtosatti@redhat.com, peter.maydell@linaro.org, pasic@linux.ibm.com, borntraeger@linux.ibm.com, dbarboza@ventanamicro.com, kvm@vger.kernel.org, qemu-arm@nongnu.org, qemu-s390x@nongnu.org References: <20230722062115.11950-2-ajones@ventanamicro.com> From: Thomas Huth In-Reply-To: <20230722062115.11950-2-ajones@ventanamicro.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=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.093, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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 22/07/2023 08.21, Andrew Jones wrote: > Since Linux commit 00f918f61c56 ("RISC-V: KVM: Skeletal in-kernel AIA > irqchip support") checking KVM_CAP_IRQCHIP returns non-zero when the > RISC-V platform has AIA. The cap indicates KVM supports at least one > of the following ioctls: > > KVM_CREATE_IRQCHIP > KVM_IRQ_LINE > KVM_GET_IRQCHIP > KVM_SET_IRQCHIP > KVM_GET_LAPIC > KVM_SET_LAPIC > > but the cap doesn't imply that KVM must support any of those ioctls > in particular. However, QEMU was assuming the KVM_CREATE_IRQCHIP > ioctl was supported. Stop making that assumption by introducing a > KVM parameter that each architecture which supports KVM_CREATE_IRQCHIP > sets. Adding parameters isn't awesome, but given how the > KVM_CAP_IRQCHIP isn't very helpful on its own, we don't have a lot of > options. > > Signed-off-by: Andrew Jones > --- > > While this fixes booting guests on riscv KVM with AIA it's unlikely > to get merged before the QEMU support for KVM AIA[1] lands, which > would also fix the issue. I think this patch is still worth considering > though since QEMU's assumption is wrong. > > [1] https://lore.kernel.org/all/20230714084429.22349-1-yongxuan.wang@sifive.com/ > > > accel/kvm/kvm-all.c | 5 ++++- > include/sysemu/kvm.h | 1 + > target/arm/kvm.c | 3 +++ > target/i386/kvm/kvm.c | 2 ++ > target/s390x/kvm/kvm.c | 3 +++ > 5 files changed, 13 insertions(+), 1 deletion(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index 373d876c0580..0f5ff8630502 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -86,6 +86,7 @@ struct KVMParkedVcpu { > }; > > KVMState *kvm_state; > +bool kvm_has_create_irqchip; > bool kvm_kernel_irqchip; > bool kvm_split_irqchip; > bool kvm_async_interrupts_allowed; > @@ -2377,8 +2378,10 @@ static void kvm_irqchip_create(KVMState *s) > if (s->kernel_irqchip_split == ON_OFF_AUTO_ON) { > error_report("Split IRQ chip mode not supported."); > exit(1); > - } else { > + } else if (kvm_has_create_irqchip) { > ret = kvm_vm_ioctl(s, KVM_CREATE_IRQCHIP); > + } else { > + return; > } > } > if (ret < 0) { I think I'd do this differntly... at the beginning of the function, there is a check for kvm_check_extension(s, KVM_CAP_IRQCHIP) etc. ... I think you could now replace that check with a simple if (!kvm_has_create_irqchip) { return; } The "kvm_vm_enable_cap(s, KVM_CAP_S390_IRQCHIP, 0)" of course has to be moved to the target/s390x/kvm/kvm.c file, too. Thomas > diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h > index 115f0cca79d1..84b1bb3dc91e 100644 > --- a/include/sysemu/kvm.h > +++ b/include/sysemu/kvm.h > @@ -32,6 +32,7 @@ > #ifdef CONFIG_KVM_IS_POSSIBLE > > extern bool kvm_allowed; > +extern bool kvm_has_create_irqchip; > extern bool kvm_kernel_irqchip; > extern bool kvm_split_irqchip; > extern bool kvm_async_interrupts_allowed; > diff --git a/target/arm/kvm.c b/target/arm/kvm.c > index b4c7654f4980..2fa87b495d68 100644 > --- a/target/arm/kvm.c > +++ b/target/arm/kvm.c > @@ -250,6 +250,9 @@ int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa) > int kvm_arch_init(MachineState *ms, KVMState *s) > { > int ret = 0; > + > + kvm_has_create_irqchip = kvm_check_extension(s, KVM_CAP_IRQCHIP); > + > /* For ARM interrupt delivery is always asynchronous, > * whether we are using an in-kernel VGIC or not. > */ > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index ebfaf3d24c79..6363e67f092d 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -2771,6 +2771,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > } > } > > + kvm_has_create_irqchip = kvm_check_extension(s, KVM_CAP_IRQCHIP); > + > return 0; > } > > diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c > index a9e5880349d9..c053304adf94 100644 > --- a/target/s390x/kvm/kvm.c > +++ b/target/s390x/kvm/kvm.c > @@ -391,6 +391,9 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > } > > kvm_set_max_memslot_size(KVM_SLOT_MAX_BYTES); > + > + kvm_has_create_irqchip = kvm_check_extension(s, KVM_CAP_S390_IRQCHIP); > + > return 0; > } >