x86/cpu/AMD: Handle SME reduction in physical address size

When System Memory Encryption (SME) is enabled, the physical address
space is reduced. Adjust the x86_phys_bits value to reflect this
reduction.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/593c037a3cad85ba92f3d061ffa7462e9ce3531d.1500319216.git.thomas.lendacky@amd.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/amd.c

@@ -613,20 +613,22 @@ static void early_init_amd(struct cpuinfo_x86 *c)
 		set_cpu_bug(c, X86_BUG_AMD_E400);
 
 	/*
-	 * BIOS support is required for SME. If BIOS has not enabled SME
-	 * then don't advertise the feature (set in scattered.c). Also,
-	 * since the SME support requires long mode, don't advertise the
-	 * feature under CONFIG_X86_32.
+	 * BIOS support is required for SME. If BIOS has enabled SME then
+	 * adjust x86_phys_bits by the SME physical address space reduction
+	 * value. If BIOS has not enabled SME then don't advertise the
+	 * feature (set in scattered.c). Also, since the SME support requires
+	 * long mode, don't advertise the feature under CONFIG_X86_32.
 	 */
 	if (cpu_has(c, X86_FEATURE_SME)) {
-		if (IS_ENABLED(CONFIG_X86_32)) {
-			clear_cpu_cap(c, X86_FEATURE_SME);
-		} else {
 		u64 msr;
 
 		/* Check if SME is enabled */
 		rdmsrl(MSR_K8_SYSCFG, msr);
-			if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
+		if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT) {
+			c->x86_phys_bits -= (cpuid_ebx(0x8000001f) >> 6) & 0x3f;
+			if (IS_ENABLED(CONFIG_X86_32))
+				clear_cpu_cap(c, X86_FEATURE_SME);
+		} else {
 			clear_cpu_cap(c, X86_FEATURE_SME);
 		}
 	}