diff --git a/target-arm/kvm.c b/target-arm/kvm.c index 969ab0bab51760ddf29f7c7916ed36e5e935d4c2..36710320f082ec2aeb5f63ea9a29a4acd9b0c5d2 100644 --- a/target-arm/kvm.c +++ b/target-arm/kvm.c @@ -62,13 +62,18 @@ bool kvm_arm_create_scratch_host_vcpu(const uint32_t *cpus_to_try, goto err; } + if (!init) { + /* Caller doesn't want the VCPU to be initialized, so skip it */ + goto finish; + } + ret = ioctl(vmfd, KVM_ARM_PREFERRED_TARGET, init); if (ret >= 0) { ret = ioctl(cpufd, KVM_ARM_VCPU_INIT, init); if (ret < 0) { goto err; } - } else { + } else if (cpus_to_try) { /* Old kernel which doesn't know about the * PREFERRED_TARGET ioctl: we know it will only support * creating one kind of guest CPU which is its preferred @@ -85,8 +90,15 @@ bool kvm_arm_create_scratch_host_vcpu(const uint32_t *cpus_to_try, if (ret < 0) { goto err; } + } else { + /* Treat a NULL cpus_to_try argument the same as an empty + * list, which means we will fail the call since this must + * be an old kernel which doesn't support PREFERRED_TARGET. + */ + goto err; } +finish: fdarray[0] = kvmfd; fdarray[1] = vmfd; fdarray[2] = cpufd; diff --git a/target-arm/kvm_arm.h b/target-arm/kvm_arm.h index 07f0c72199ee788764838cc007def0d4dc0bcdf2..345233c18bed98f8aaf0eef283119e10f6bd55c4 100644 --- a/target-arm/kvm_arm.h +++ b/target-arm/kvm_arm.h @@ -124,9 +124,12 @@ void kvm_arm_reset_vcpu(ARMCPU *cpu); * kvm_arm_create_scratch_host_vcpu: * @cpus_to_try: array of QEMU_KVM_ARM_TARGET_* values (terminated with * QEMU_KVM_ARM_TARGET_NONE) to try as fallback if the kernel does not - * know the PREFERRED_TARGET ioctl + * know the PREFERRED_TARGET ioctl. Passing NULL is the same as passing + * an empty array. * @fdarray: filled in with kvmfd, vmfd, cpufd file descriptors in that order - * @init: filled in with the necessary values for creating a host vcpu + * @init: filled in with the necessary values for creating a host + * vcpu. If NULL is provided, will not init the vCPU (though the cpufd + * will still be set up). * * Create a scratch vcpu in its own VM of the type preferred by the host * kernel (as would be used for '-cpu host'), for purposes of probing it