Before this change, the default KVM type, which is used for non-virt machine models, was 0. The kernel documentation says: > On arm64, the physical address size for a VM (IPA Size limit) is > limited to 40bits by default. The limit can be configured if the host > supports the extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use > KVM_VM_TYPE_ARM_IPA_SIZE(IPA_Bits) to set the size in the machine type > identifier, where IPA_Bits is the maximum width of any physical > address used by the VM. The IPA_Bits is encoded in bits[7-0] of the > machine type identifier. > > e.g, to configure a guest to use 48bit physical address size:: > > vm_fd = ioctl(dev_fd, KVM_CREATE_VM, KVM_VM_TYPE_ARM_IPA_SIZE(48)); > > The requested size (IPA_Bits) must be: > > == ========================================================= > 0 Implies default size, 40bits (for backward compatibility) > N Implies N bits, where N is a positive integer such that, > 32 <= N <= Host_IPA_Limit > == ========================================================= > Host_IPA_Limit is the maximum possible value for IPA_Bits on the host > and is dependent on the CPU capability and the kernel configuration. > The limit can be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the > KVM_CHECK_EXTENSION ioctl() at run-time. > > Creation of the VM will fail if the requested IPA size (whether it is > implicit or explicit) is unsupported on the host. https://docs.kernel.org/virt/kvm/api.html#kvm-create-vm So if Host_IPA_Limit < 40, specifying 0 as the type will fail. This actually confused libvirt, which uses "none" machine model to probe the KVM availability, on M2 MacBook Air. Fix this by using Host_IPA_Limit as the default type when KVM_CAP_ARM_VM_IPA_SIZE is available. Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> --- target/arm/kvm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/target/arm/kvm.c b/target/arm/kvm.c index 40f577bfd5..23aeb09949 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -249,7 +249,9 @@ int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa) int kvm_arch_get_default_type(MachineState *ms) { - return 0; + bool fixed_ipa; + int size = kvm_arm_get_max_vm_ipa_size(ms, &fixed_ipa); + return fixed_ipa ? 0 : size; } int kvm_arch_init(MachineState *ms, KVMState *s) -- 2.41.0
