diff options
Diffstat (limited to 'arch/x86/realmode/rm/trampoline_64.S')
| -rw-r--r-- | arch/x86/realmode/rm/trampoline_64.S | 24 |
1 files changed, 24 insertions, 0 deletions
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" |