Disable PAUSE/MWAIT/HLT exits after vCPUs have been created is useless, because PAUSE/MWAIT/HLT intercepts configuration is not changed after vCPU created. And two vCPUs may have inconsistent configuration if disable PAUSE/MWAIT/HLT exits between those two vCPUs creation. Since it's a per-VM capability, all vCPUs should keep same configuration, so disallow enable KVM_CAP_X86_DISABLE_EXITS capability after vCPUs have been created. Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx> --- Documentation/virt/kvm/api.rst | 3 ++- arch/x86/kvm/x86.c | 5 +++++ 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index a69e91088d76..95a683a27cf2 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -7179,7 +7179,8 @@ branch to guests' 0x200 interrupt vector. :Architectures: x86 :Parameters: args[0] defines which exits are disabled -:Returns: 0 on success, -EINVAL when args[0] contains invalid exits +:Returns: 0 on success, -EINVAL when args[0] contains invalid exits or + any vCPUs have been created. Valid bits in args[0] are:: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2c0ff40e5345..7e97595465fc 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6275,6 +6275,9 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, if (cap->args[0] & ~KVM_X86_DISABLE_VALID_EXITS) break; + mutex_lock(&kvm->lock); + if (kvm->created_vcpus) + goto disable_exits_unlock; if (cap->args[0] & KVM_X86_DISABLE_EXITS_PAUSE) kvm->arch.pause_in_guest = true; @@ -6296,6 +6299,8 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, } r = 0; +disable_exits_unlock: + mutex_unlock(&kvm->lock); break; case KVM_CAP_MSR_PLATFORM_INFO: kvm->arch.guest_can_read_msr_platform_info = cap->args[0]; base-commit: 27d6845d258b67f4eb3debe062b7dacc67e0c393 -- 2.31.1
