x86/vmx: Fix vmentry failure because of invalid LER on Broadwell

x86/vmx: Fix vmentry failure because of invalid LER on Broadwell

Occasionally, on certain Broadwell CPUs MSR_IA32_LASTINTTOIP has been
observed to have the top three bits corrupted as though the MSR is using
the LBR_FORMAT_EIP_FLAGS_TSX format. This is incorrect and causes a
vmentry failure -- the MSR should contain an offset into the current
code segment. This is assumed to be erratum BDF14. Workaround the issue
by sign-extending into bits 48:63 for MSR_IA32_LASTINT{FROM,TO}IP.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>