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authorTom Lendacky <thomas.lendacky@amd.com>2017-07-18 00:10:25 +0300
committerIngo Molnar <mingo@kernel.org>2017-07-18 12:38:04 +0300
commit46d010e04a637ca5bbdd0ff72554d9c06f2961c9 (patch)
treefc271074abda4140738afe0c95c37a2e8991ae1a /arch/x86/realmode
parent2543a786aa25258451f3418b87a038c7ddaa2e85 (diff)
downloadlinux-46d010e04a637ca5bbdd0ff72554d9c06f2961c9.tar.xz
x86/boot/realmode: Check for memory encryption on the APs
Add support to check if memory encryption is active in the kernel and that it has been enabled on the AP. If memory encryption is active in the kernel but has not been enabled on the AP, then set the memory encryption bit (bit 23) of MSR_K8_SYSCFG to enable memory encryption on that AP and allow the AP to continue start up. 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/37e29b99c395910f56ca9f8ecf7b0439b28827c8.1500319216.git.thomas.lendacky@amd.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/realmode')
-rw-r--r--arch/x86/realmode/init.c4
-rw-r--r--arch/x86/realmode/rm/trampoline_64.S24
2 files changed, 28 insertions, 0 deletions
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index d6ddc7e60884..1f71980fc5e0 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -108,6 +108,10 @@ static void __init setup_real_mode(void)
trampoline_cr4_features = &trampoline_header->cr4;
*trampoline_cr4_features = mmu_cr4_features;
+ trampoline_header->flags = 0;
+ if (sme_active())
+ trampoline_header->flags |= TH_FLAGS_SME_ACTIVE;
+
trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
trampoline_pgd[0] = trampoline_pgd_entry.pgd;
trampoline_pgd[511] = init_top_pgt[511].pgd;
diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
index dac7b20d2f9d..614fd7064d0a 100644
--- a/arch/x86/realmode/rm/trampoline_64.S
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -30,6 +30,7 @@
#include <asm/msr.h>
#include <asm/segment.h>
#include <asm/processor-flags.h>
+#include <asm/realmode.h>
#include "realmode.h"
.text
@@ -92,6 +93,28 @@ ENTRY(startup_32)
movl %edx, %fs
movl %edx, %gs
+ /*
+ * Check for memory encryption support. This is a safety net in
+ * case BIOS hasn't done the necessary step of setting the bit in
+ * the MSR for this AP. If SME is active and we've gotten this far
+ * then it is safe for us to set the MSR bit and continue. If we
+ * don't we'll eventually crash trying to execute encrypted
+ * instructions.
+ */
+ bt $TH_FLAGS_SME_ACTIVE_BIT, pa_tr_flags
+ jnc .Ldone
+ movl $MSR_K8_SYSCFG, %ecx
+ rdmsr
+ bts $MSR_K8_SYSCFG_MEM_ENCRYPT_BIT, %eax
+ jc .Ldone
+
+ /*
+ * Memory encryption is enabled but the SME enable bit for this
+ * CPU has has not been set. It is safe to set it, so do so.
+ */
+ wrmsr
+.Ldone:
+
movl pa_tr_cr4, %eax
movl %eax, %cr4 # Enable PAE mode
@@ -147,6 +170,7 @@ GLOBAL(trampoline_header)
tr_start: .space 8
GLOBAL(tr_efer) .space 8
GLOBAL(tr_cr4) .space 4
+ GLOBAL(tr_flags) .space 4
END(trampoline_header)
#include "trampoline_common.S"