target/i386: add control bits support for LAM

target/i386: add control bits support for LAM

LAM uses CR3[61] and CR3[62] to configure/enable LAM on user pointers.
LAM uses CR4[28] to configure/enable LAM on supervisor pointers.

For CR3 LAM bits, no additional handling needed:
- TCG
  LAM is not supported for TCG of target-i386.  helper_write_crN() and
  helper_vmrun() check max physical address bits before calling
  cpu_x86_update_cr3(), no change needed, i.e. CR3 LAM bits are not allowed
  to be set in TCG.
- gdbstub
  x86_cpu_gdb_write_register() will call cpu_x86_update_cr3() to update cr3.
  Allow gdb to set the LAM bit(s) to CR3, if vcpu doesn't support LAM,
  KVM_SET_SREGS will fail as other reserved bits.

For CR4 LAM bit, its reservation depends on vcpu supporting LAM feature or
not.
- TCG
  LAM is not supported for TCG of target-i386.  helper_write_crN() and
  helper_vmrun() check CR4 reserved bit before calling cpu_x86_update_cr4(),
  i.e. CR4 LAM bit is not allowed to be set in TCG.
- gdbstub
  x86_cpu_gdb_write_register() will call cpu_x86_update_cr4() to update cr4.
  Mask out LAM bit on CR4 if vcpu doesn't support LAM.
- x86_cpu_reset_hold() doesn't need special handling.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Message-ID: <20240112060042.19925-3-binbin.wu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>