x86, intel_txt: Intel TXT reboot/halt shutdown support

Support for graceful handling of kernel reboots after an Intel(R) TXT launch.

Without this patch, attempting to reboot or halt the system will cause the
TXT hardware to lock memory upon system restart because the secrets-in-memory
flag that was set on launch was never cleared.  This will in turn cause BIOS
to execute a TXT Authenticated Code Module (ACM) that will scrub all of memory
and then unlock it.  Depending on the amount of memory in the system and its type,
this may take some time.

This patch creates a 1:1 address mapping to the tboot module and then calls back
into tboot so that it may properly and securely clean up system state and clear
the secrets-in-memory flag.  When it has completed these steps, the tboot module
will reboot or halt the system.

 arch/x86/kernel/reboot.c |    8 ++++++++
 init/main.c              |    3 +++
 2 files changed, 11 insertions(+)

Signed-off-by: Joseph Cihula <joseph.cihula@intel.com>
Signed-off-by: Shane Wang <shane.wang@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index d2d1ce8170f06c8573ac022f4e49dfc59a371c9b..9de01c5d979409243cefb0ae8164023f05d5a00c 100644 (file)
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -24,6 +24,8 @@
 # include <asm/iommu.h>
 #endif
 
+#include <asm/tboot.h>
+
 /*
  * Power off function, if any
  */
@@ -460,6 +462,8 @@ static void native_machine_emergency_restart(void)
        if (reboot_emergency)
                emergency_vmx_disable_all();
 
+       tboot_shutdown(TB_SHUTDOWN_REBOOT);
+
        /* Tell the BIOS if we want cold or warm reboot */
        *((unsigned short *)__va(0x472)) = reboot_mode;
 
@@ -586,6 +590,8 @@ static void native_machine_halt(void)
        /* stop other cpus and apics */
        machine_shutdown();
 
+       tboot_shutdown(TB_SHUTDOWN_HALT);
+
        /* stop this cpu */
        stop_this_cpu(NULL);
 }
@@ -597,6 +603,8 @@ static void native_machine_power_off(void)
                        machine_shutdown();
                pm_power_off();
        }
+       /* a fallback in case there is no PM info available */
+       tboot_shutdown(TB_SHUTDOWN_HALT);
 }
 
 struct machine_ops machine_ops = {

diff --git a/init/main.c b/init/main.c
index 2c5ade79eb81718702dd1fdf44e8b129e69f88a9..56ada27c4f478f51a8dc302128608362b0011fdb 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -73,6 +73,7 @@
 #include <asm/io.h>
 #include <asm/bugs.h>
 #include <asm/setup.h>
+#include <asm/tboot.h>
 #include <asm/sections.h>
 #include <asm/cacheflush.h>
 
@@ -715,6 +716,8 @@ asmlinkage void __init start_kernel(void)
 
        ftrace_init();
 
+       tboot_create_trampoline();
+
        /* Do the rest non-__init'ed, we're now alive */
        rest_init();
 }