target/arm/kvm: Drop support for kernels without KVM_ARM_PREFERRED_TARGET

Our KVM code includes backwards compatibility support for ancient
kernels which don't support the KVM_ARM_PREFERRED_TARGET ioctl.  This
ioctl was introduced in kernel commit 42c4e0c77ac91 in September
2013 and is in v3.12, so it's reasonable to assume it's present.

(We already dropped support for kernels without KVM_CAP_DEVICE_CTRL,
a feature added to the kernel in April 2013, in our commit
84f298ea3e; so there are only about six months' worth of kernels,
from v3.9 to v3.11, that we don't already fail to run on and that
this commit is dropping handling for.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250318114222.1018200-1-peter.maydell@linaro.org

target/arm/kvm_arm.h

@@ -97,10 +97,6 @@ void kvm_arm_reset_vcpu(ARMCPU *cpu);
 #ifdef CONFIG_KVM
 /**
  * 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. 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. If NULL is provided, will not init the vCPU (though the cpufd
@@ -113,8 +109,7 @@ void kvm_arm_reset_vcpu(ARMCPU *cpu);
  * Returns: true on success (and fdarray and init are filled in),
  * false on failure (and fdarray and init are not valid).
  */
-bool kvm_arm_create_scratch_host_vcpu(const uint32_t *cpus_to_try,
-                                      int *fdarray,
+bool kvm_arm_create_scratch_host_vcpu(int *fdarray,
                                       struct kvm_vcpu_init *init);
 
 /**