x86, intel_txt: Intel TXT Sx shutdown support

Support for graceful handling of sleep states (S3/S4/S5) after an Intel(R) TXT launch.

Without this patch, attempting to place the system in one of the ACPI sleep
states (S3/S4/S5) will cause the TXT hardware to treat this as an attack and
will cause a system reset, with memory locked.  Not only may the subsequent
memory scrub take some time, but the platform will be unable to enter the
requested power state.

This patch calls back into the tboot so that it may properly and securely clean
up system state and clear the secrets-in-memory flag, after which it will place
the system into the requested sleep state using ACPI information passed by the kernel.

 arch/x86/kernel/smpboot.c     |    2 ++
 drivers/acpi/acpica/hwsleep.c |    3 +++
 kernel/cpu.c                  |    7 ++++++-
 3 files changed, 11 insertions(+), 1 deletion(-)

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>

1 files changed, 6 insertions, 1 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 8ce10043e4ac..ff071e022a85 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -14,6 +14,7 @@
 #include <linux/kthread.h>
 #include <linux/stop_machine.h>
 #include <linux/mutex.h>
+#include <asm/tboot.h>
 
 #ifdef CONFIG_SMP
 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
@@ -376,7 +377,7 @@ static cpumask_var_t frozen_cpus;
 
 int disable_nonboot_cpus(void)
 {
-        int cpu, first_cpu, error;
+        int cpu, first_cpu, error, num_cpus = 0;
 
         error = stop_machine_create();
         if (error)
@@ -391,6 +392,7 @@ int disable_nonboot_cpus(void)
         for_each_online_cpu(cpu) {
                 if (cpu == first_cpu)
                         continue;
+                num_cpus++;
                 error = _cpu_down(cpu, 1);
                 if (!error) {
                         cpumask_set_cpu(cpu, frozen_cpus);
@@ -401,6 +403,9 @@ int disable_nonboot_cpus(void)
                         break;
                 }
         }
+        /* ensure all CPUs have gone into wait-for-SIPI */
+        error |= tboot_wait_for_aps(num_cpus);
+
         if (!error) {
                 BUG_ON(num_online_cpus() > 1);
                 /* Make sure the CPUs won't be enabled by someone else */