linux-kernel - [PATCH v3 12/14] reboot: Secure Launch SEXIT support on reboot paths

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Message-Id: <1628527136-2478-13-git-send-email-ross.philipson@oracle.com>
Date:   Mon,  9 Aug 2021 12:38:54 -0400
From:   Ross Philipson <ross.philipson@...cle.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org,
        iommu@...ts.linux-foundation.org, linux-integrity@...r.kernel.org,
        linux-doc@...r.kernel.org
Cc:     ross.philipson@...cle.com, dpsmith@...rtussolutions.com,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        luto@...capital.net, kanth.ghatraju@...cle.com,
        trenchboot-devel@...glegroups.com
Subject: [PATCH v3 12/14] reboot: Secure Launch SEXIT support on reboot paths

If the MLE kernel is being powered off, rebooted or halted,
then SEXIT must be called. Note that the SEXIT GETSEC leaf
can only be called after a machine_shutdown() has been done on
these paths. The machine_shutdown() is not called on a few paths
like when poweroff action does not have a poweroff callback (into
ACPI code) or when an emergency reset is done. In these cases,
just the TXT registers are finalized but SEXIT is skipped.

Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
---
 arch/x86/kernel/reboot.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index ebfb911..fe9d8cc 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -12,6 +12,7 @@
 #include <linux/delay.h>
 #include <linux/objtool.h>
 #include <linux/pgtable.h>
+#include <linux/slaunch.h>
 #include <acpi/reboot.h>
 #include <asm/io.h>
 #include <asm/apic.h>
@@ -731,6 +732,7 @@ static void native_machine_restart(char *__unused)
 
 	if (!reboot_force)
 		machine_shutdown();
+	slaunch_finalize(!reboot_force);
 	__machine_emergency_restart(0);
 }
 
@@ -741,6 +743,9 @@ static void native_machine_halt(void)
 
 	tboot_shutdown(TB_SHUTDOWN_HALT);
 
+	/* SEXIT done after machine_shutdown() to meet TXT requirements */
+	slaunch_finalize(1);
+
 	stop_this_cpu(NULL);
 }
 
@@ -749,8 +754,12 @@ static void native_machine_power_off(void)
 	if (pm_power_off) {
 		if (!reboot_force)
 			machine_shutdown();
+		slaunch_finalize(!reboot_force);
 		pm_power_off();
+	} else {
+		slaunch_finalize(0);
 	}
+
 	/* A fallback in case there is no PM info available */
 	tboot_shutdown(TB_SHUTDOWN_HALT);
 }
@@ -778,6 +787,7 @@ void machine_shutdown(void)
 
 void machine_emergency_restart(void)
 {
+	slaunch_finalize(0);
 	__machine_emergency_restart(1);
 }
 
-- 
1.8.3.1