diff options
| author | Tom Lendacky <thomas.lendacky@amd.com> | 2017-10-20 09:30:54 -0500 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-11-07 15:35:58 +0100 |
| commit | 1958b5fc401067662ec11a6fcbe0daa26c813603 (patch) | |
| tree | b1a58839156d97523caeb506a810a74eccc56d58 /arch/x86/boot/compressed/head_64.S | |
| parent | d7b417fa08d1187923c270bc33a3555c2fcff8b9 (diff) | |
x86/boot: Add early boot support when running with SEV active
Early in the boot process, add checks to determine if the kernel is
running with Secure Encrypted Virtualization (SEV) active.
Checking for SEV requires checking that the kernel is running under a
hypervisor (CPUID 0x00000001, bit 31), that the SEV feature is available
(CPUID 0x8000001f, bit 1) and then checking a non-interceptable SEV MSR
(0xc0010131, bit 0).
This check is required so that during early compressed kernel booting the
pagetables (both the boot pagetables and KASLR pagetables (if enabled) are
updated to include the encryption mask so that when the kernel is
decompressed into encrypted memory, it can boot properly.
After the kernel is decompressed and continues booting the same logic is
used to check if SEV is active and set a flag indicating so. This allows
to distinguish between SME and SEV, each of which have unique differences
in how certain things are handled: e.g. DMA (always bounce buffered with
SEV) or EFI tables (always access decrypted with SME).
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: kvm@vger.kernel.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20171020143059.3291-13-brijesh.singh@amd.com
Diffstat (limited to 'arch/x86/boot/compressed/head_64.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index beb255b66447..20919b4f3133 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -131,6 +131,19 @@ ENTRY(startup_32) /* * Build early 4G boot pagetable */ + /* + * If SEV is active then set the encryption mask in the page tables. + * This will insure that when the kernel is copied and decompressed + * it will be done so encrypted. + */ + call get_sev_encryption_bit + xorl %edx, %edx + testl %eax, %eax + jz 1f + subl $32, %eax /* Encryption bit is always above bit 31 */ + bts %eax, %edx /* Set encryption mask for page tables */ +1: + /* Initialize Page tables to 0 */ leal pgtable(%ebx), %edi xorl %eax, %eax @@ -141,12 +154,14 @@ ENTRY(startup_32) leal pgtable + 0(%ebx), %edi leal 0x1007 (%edi), %eax movl %eax, 0(%edi) + addl %edx, 4(%edi) /* Build Level 3 */ leal pgtable + 0x1000(%ebx), %edi leal 0x1007(%edi), %eax movl $4, %ecx 1: movl %eax, 0x00(%edi) + addl %edx, 0x04(%edi) addl $0x00001000, %eax addl $8, %edi decl %ecx @@ -157,6 +172,7 @@ ENTRY(startup_32) movl $0x00000183, %eax movl $2048, %ecx 1: movl %eax, 0(%edi) + addl %edx, 4(%edi) addl $0x00200000, %eax addl $8, %edi decl %ecx |