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Subject[tip:x86/mm] x86/cpu/AMD: Handle SME reduction in physical address size
Commit-ID:  9af9b94068fb1ea3206a700fc222075966fbef14
Gitweb: http://git.kernel.org/tip/9af9b94068fb1ea3206a700fc222075966fbef14
Author: Tom Lendacky <thomas.lendacky@amd.com>
AuthorDate: Mon, 17 Jul 2017 16:10:02 -0500
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 18 Jul 2017 11:37:59 +0200

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.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/cpu/amd.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 5ccc7b2..4d87950 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -613,21 +613,23 @@ 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;
+ u64 msr;

- /* Check if SME is enabled */
- rdmsrl(MSR_K8_SYSCFG, msr);
- if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
+ /* Check if SME is enabled */
+ rdmsrl(MSR_K8_SYSCFG, msr);
+ 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);
}
}
}
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