Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753613AbbHEQgi (ORCPT ); Wed, 5 Aug 2015 12:36:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57504 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753199AbbHEQgh (ORCPT ); Wed, 5 Aug 2015 12:36:37 -0400 Subject: Re: [PATCH v2 4/5] KVM: add KVM_USER_EXIT vcpu ioctl for userspace exit To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org References: <1438792381-19453-1-git-send-email-rkrcmar@redhat.com> <1438792381-19453-5-git-send-email-rkrcmar@redhat.com> Cc: kvm@vger.kernel.org From: Paolo Bonzini Message-ID: <55C23B91.4010900@redhat.com> Date: Wed, 5 Aug 2015 18:36:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <1438792381-19453-5-git-send-email-rkrcmar@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5734 Lines: 175 On 05/08/2015 18:33, Radim Krčmář wrote: > The guest can use KVM_USER_EXIT instead of a signal-based exiting to > userspace. Availability depends on KVM_CAP_USER_EXIT. > Only x86 is implemented so far. > > Signed-off-by: Radim Krčmář > --- > v2: > * use vcpu ioctl instead of vm one [4/5] > * shrink kvm_user_exit from 64 to 32 bytes [4/5] > > Documentation/virtual/kvm/api.txt | 30 ++++++++++++++++++++++++++++++ > arch/x86/kvm/x86.c | 24 ++++++++++++++++++++++++ > include/uapi/linux/kvm.h | 7 +++++++ > virt/kvm/kvm_main.c | 5 +++-- > 4 files changed, 64 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt > index 3c714d43a717..c5844f0b8e7c 100644 > --- a/Documentation/virtual/kvm/api.txt > +++ b/Documentation/virtual/kvm/api.txt > @@ -3020,6 +3020,36 @@ Returns: 0 on success, -1 on error > > Queues an SMI on the thread's vcpu. > > + > +4.97 KVM_USER_EXIT > + > +Capability: KVM_CAP_USER_EXIT > +Architectures: x86 > +Type: vcpu ioctl > +Parameters: struct kvm_user_exit (in) > +Returns: 0 on success, > + -EFAULT if the parameter couldn't be read, > + -EINVAL if 'reserved' is not zeroed, > + > +struct kvm_user_exit { > + __u8 reserved[32]; > +}; > + > +The ioctl is asynchronous to VCPU execution and can be issued from all threads. > + > +Make vcpu_id exit to userspace as soon as possible. If the VCPU is not running > +in kernel at the time, it will exit early on the next call to KVM_RUN. > +If the VCPU was going to exit because of other reasons when KVM_USER_EXIT was > +issued, it will keep the original exit reason and not exit early on next > +KVM_RUN. > +If VCPU exited because of KVM_USER_EXIT, the exit reason is KVM_EXIT_REQUEST. > + > +This ioctl has very similar effect (same sans some races on userspace exit) as > +sending a signal (that is blocked in userspace and set in KVM_SET_SIGNAL_MASK) > +to the VCPU thread. Can we just return EINVAL if the parameter is not NULL? Paolo > + > + > + > 5. The kvm_run structure > ------------------------ > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 3493457ad0a1..27d777eb34e4 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2466,6 +2466,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_ASSIGN_DEV_IRQ: > case KVM_CAP_PCI_2_3: > #endif > + case KVM_CAP_USER_EXIT: > r = 1; > break; > case KVM_CAP_X86_SMM: > @@ -3077,6 +3078,20 @@ static int kvm_set_guest_paused(struct kvm_vcpu *vcpu) > return 0; > } > > +int kvm_vcpu_ioctl_user_exit(struct kvm_vcpu *vcpu, struct kvm_user_exit *info) > +{ > + struct kvm_user_exit valid = {}; > + BUILD_BUG_ON(sizeof(valid) != 32); > + > + if (memcmp(info, &valid, sizeof(valid))) > + return -EINVAL; > + > + kvm_make_request(KVM_REQ_EXIT, vcpu); > + kvm_vcpu_kick(vcpu); > + > + return 0; > +} > + > long kvm_arch_vcpu_ioctl(struct file *filp, > unsigned int ioctl, unsigned long arg) > { > @@ -3341,6 +3356,15 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > r = kvm_set_guest_paused(vcpu); > goto out; > } > + case KVM_USER_EXIT: { > + struct kvm_user_exit info; > + > + r = -EFAULT; > + if (copy_from_user(&info, argp, sizeof(info))) > + goto out; > + r = kvm_vcpu_ioctl_user_exit(vcpu, &info); > + break; > + } > default: > r = -EINVAL; > } > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index d996a7cdb4d2..bc5a1abe9626 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -826,6 +826,7 @@ struct kvm_ppc_smmu_info { > #define KVM_CAP_X86_SMM 117 > #define KVM_CAP_MULTI_ADDRESS_SPACE 118 > #define KVM_CAP_SPLIT_IRQCHIP 119 > +#define KVM_CAP_USER_EXIT 120 > > #ifdef KVM_CAP_IRQ_ROUTING > > @@ -1008,6 +1009,10 @@ struct kvm_device_attr { > __u64 addr; /* userspace address of attr data */ > }; > > +struct kvm_user_exit { > + __u8 reserved[32]; > +}; > + > #define KVM_DEV_VFIO_GROUP 1 > #define KVM_DEV_VFIO_GROUP_ADD 1 > #define KVM_DEV_VFIO_GROUP_DEL 2 > @@ -1119,6 +1124,8 @@ struct kvm_s390_ucas_mapping { > #define KVM_ARM_SET_DEVICE_ADDR _IOW(KVMIO, 0xab, struct kvm_arm_device_addr) > /* Available with KVM_CAP_PPC_RTAS */ > #define KVM_PPC_RTAS_DEFINE_TOKEN _IOW(KVMIO, 0xac, struct kvm_rtas_token_args) > +/* Available with KVM_CAP_USER_EXIT */ > +#define KVM_USER_EXIT _IOW(KVMIO, 0xad, struct kvm_user_exit) > > /* ioctl for vm fd */ > #define KVM_CREATE_DEVICE _IOWR(KVMIO, 0xe0, struct kvm_create_device) > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index b34a328fdac1..d7ffe6090520 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2248,15 +2248,16 @@ static long kvm_vcpu_ioctl(struct file *filp, > if (unlikely(_IOC_TYPE(ioctl) != KVMIO)) > return -EINVAL; > > -#if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS) > /* > * Special cases: vcpu ioctls that are asynchronous to vcpu execution, > * so vcpu_load() would break it. > */ > +#if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS) > if (ioctl == KVM_S390_INTERRUPT || ioctl == KVM_S390_IRQ || ioctl == KVM_INTERRUPT) > return kvm_arch_vcpu_ioctl(filp, ioctl, arg); > #endif > - > + if (ioctl == KVM_USER_EXIT) > + return kvm_arch_vcpu_ioctl(filp, ioctl, arg); > > r = vcpu_load(vcpu); > if (r) > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/