This is an example on how to use the new CPU options. This catters to distributions who want machines to be migratable (forward and backward) accross different host kernel versions in case KVM registers exposed to qemu vary accross kernels. This patch is not meant to be upstreamed as it is really kernel dependent. The goal is to illustrate how this would be used.
In this example, For 10_1 machines types and older we apply the following host kernel related compats: 1) Make sure the KVM_REG_ARM_VENDOR_HYP_BMAP_2 exposed from v6.15 onwards is ignored/hidden. 2) Make sure TCR_EL1, PIRE0_EL1, PIR_EL1 are always seen by qemu although not exposed by KVM. They were unconditionnally exposed before v6.13 while from v6.13 they are only exposed if supported by the guest. This will allow 10_1 machines types and older machines to migrate forward and backward from old downstream kernels that do not feature those changes to newer kernels (>= v6.15). Signed-off-by: Eric Auger <[email protected]> --- hw/arm/virt.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/hw/arm/virt.c b/hw/arm/virt.c index 6c57e436053..860bc8a787a 100644 --- a/hw/arm/virt.c +++ b/hw/arm/virt.c @@ -3623,9 +3623,16 @@ DEFINE_VIRT_MACHINE(10, 2) static void virt_machine_10_1_options(MachineClass *mc) { + VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc)); + virt_machine_10_2_options(mc); mc->smbios_memory_device_size = 2047 * TiB; compat_props_add(mc->compat_props, hw_compat_10_1, hw_compat_10_1_len); + /* KVM_REG_ARM_VENDOR_HYP_BMAP_2 */ + arm_virt_compat_register_hidden_reg(vmc, 0x6030000000160003); + arm_virt_compat_register_safe_missing_reg(vmc, 0x603000000013c103 /* TCR_EL1 */); + arm_virt_compat_register_safe_missing_reg(vmc, 0x603000000013c512 /* PIRE0_EL1 */); + arm_virt_compat_register_safe_missing_reg(vmc, 0x603000000013c513 /* PIR_EL1 */); } DEFINE_VIRT_MACHINE(10, 1) -- 2.52.0
