x86/vvmx: Use hvm_cr4_guest_valid_bits() to calculate MSR_IA32_VMX_CR4_FIXED1

x86/vvmx: Use hvm_cr4_guest_valid_bits() to calculate MSR_IA32_VMX_CR4_FIXED1

Reuse the logic in hvm_cr4_guest_valid_bits() instead of duplicating it.

This fixes a bug to do with the handling of X86_CR4_PCE.  The RDPMC
instruction predate the architectural performance feature, and has been around
since the P6.  X86_CR4_PCE is like X86_CR4_TSD and only controls whether RDPMC
is available at cpl!=0, not whether RDPMC is generally unavailable.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>