x86/mm: Update comment in detect_tme() regarding x86_phys_bits

As Kai pointed out, the primary reason for adjusting x86_phys_bits is to
reflect that the the address space is reduced and not the ability to
communicate the available physical address space to virtual machines.

Suggested-by: Kai Huang <kai.huang@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: linux-mm@kvack.org
Link: https://lkml.kernel.org/r/20180315134907.9311-2-kirill.shutemov@linux.intel.com

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 3f8d7a3b644743ef03045acaa089ca83abddef94..6106d11ceb6bbba5961d3e27b62c16056261b652 100644 (file)
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -587,11 +587,8 @@ detect_keyid_bits:
        }
 
        /*
-        * Exclude KeyID bits from physical address bits.
-        *
-        * We have to do this even if we are not going to use KeyID bits
-        * ourself. VM guests still have to know that these bits are not usable
-        * for physical address.
+        * KeyID bits effectively lower the number of physical address
+        * bits.  Update cpuinfo_x86::x86_phys_bits accordingly.
         */
        c->x86_phys_bits -= keyid_bits;
 }