[PATCH v2 7/8] target/arm/cpu: Expose x-mig-hidden-regs and x-mig-safe-missing-regs properties

[Eric Auger <eric.auger@redhat.com>]

Allows to set both array properties along with arm cpus. Their "x-" prefix
reminds that those shall be used carefully for distro specific use cases
to garantee cross kernel migration.

This will allow to define such compat machine props like:

    static GlobalProperty arm_virt_kernel_compat_10_1[] = {
        /* KVM_REG_ARM_VENDOR_HYP_BMAP_2 */
        { TYPE_ARM_CPU, "x-mig-hidden-regs", "0x6030000000160003" },
        { TYPE_ARM_CPU, "x-mig-safe-missing-regs",
          /* TCR_EL1, PIRE0_EL1, PIR_EL1 */
          "0x603000000013c103, 0x603000000013c512, 0x603000000013c513" },
    }

The first one means KVM_REG_ARM_VENDOR_HYP_BMAP_2 shall always
been hidden for machine types older than 10.1. The second one means
that along with 10.1 machine type we may receive in the incoming
migration stream, 3 registers that are unknown on destination.

Obvioulsy, using the reg index as defined in
linux/Documentation/virt/kvm/api.rst is not user friendly. However
those options, prefixed with "x-" are supposed to be used
rarely by people who know the details.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 target/arm/cpu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 066746d76f..c41774cb4c 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -2248,6 +2248,11 @@ static const Property arm_cpu_properties[] = {
     DEFINE_PROP_BOOL("backcompat-cntfrq", ARMCPU, backcompat_cntfrq, false),
     DEFINE_PROP_BOOL("backcompat-pauth-default-use-qarma5", ARMCPU,
                       backcompat_pauth_default_use_qarma5, false),
+    DEFINE_PROP_ARRAY("x-mig-hidden-regs", ARMCPU,
+                      nr_hidden_regs, hidden_regs, qdev_prop_uint64, uint64_t),
+    DEFINE_PROP_ARRAY("x-mig-safe-missing-regs", ARMCPU,
+                      nr_mig_safe_missing_regs, mig_safe_missing_regs,
+                      qdev_prop_uint64, uint64_t),
 };
 
 static const gchar *arm_gdb_arch_name(CPUState *cs)
-- 
2.51.1