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-rw-r--r--target-arm/kvm.c14
-rw-r--r--target-arm/kvm_arm.h7
2 files changed, 18 insertions, 3 deletions
diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index 969ab0bab5..36710320f0 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 07f0c72199..345233c18b 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