linux-kernel - [PATCH v15 26/28] x86/reboot: Secure Launch SEXIT support on reboot paths

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Message-ID: <20251215233316.1076248-27-ross.philipson@oracle.com>
Date: Mon, 15 Dec 2025 15:33:14 -0800
From: Ross Philipson <ross.philipson@...cle.com>
To: linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-integrity@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-crypto@...r.kernel.org, kexec@...ts.infradead.org,
        linux-efi@...r.kernel.org, iommu@...ts.linux.dev
Cc: ross.philipson@...cle.com, dpsmith@...rtussolutions.com,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        dave.hansen@...ux.intel.com, ardb@...nel.org, mjg59@...f.ucam.org,
        James.Bottomley@...senpartnership.com, peterhuewe@....de,
        jarkko@...nel.org, jgg@...pe.ca, luto@...capital.net,
        nivedita@...m.mit.edu, herbert@...dor.apana.org.au,
        davem@...emloft.net, corbet@....net, ebiederm@...ssion.com,
        dwmw2@...radead.org, baolu.lu@...ux.intel.com,
        kanth.ghatraju@...cle.com, andrew.cooper3@...rix.com,
        trenchboot-devel@...glegroups.com
Subject: [PATCH v15 26/28] x86/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 GETSEC[SEXIT] 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>
Signed-off-by: Daniel P. Smith <dpsmith@...rtussolutions.com>
---
 arch/x86/kernel/reboot.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 964f6b0a3d68..b1e6c1972f0b 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -13,6 +13,7 @@
 #include <linux/objtool.h>
 #include <linux/pgtable.h>
 #include <linux/kexec.h>
+#include <linux/slaunch.h>
 #include <acpi/reboot.h>
 #include <asm/io.h>
 #include <asm/apic.h>
@@ -778,6 +779,12 @@ static void native_machine_restart(char *__unused)
 
 	if (!reboot_force)
 		machine_shutdown();
+	/*
+	 * The comments for slaunch_finalize() provides the explanation for the
+	 * conditions required to do the SEXIT op reflected in the conditional
+	 * parameter do_sexit.
+	 */
+	slaunch_finalize(!reboot_force);
 	__machine_emergency_restart(0);
 }
 
@@ -788,6 +795,8 @@ static void native_machine_halt(void)
 
 	tboot_shutdown(TB_SHUTDOWN_HALT);
 
+	slaunch_finalize(1);
+
 	stop_this_cpu(NULL);
 }
 
@@ -796,8 +805,12 @@ static void native_machine_power_off(void)
 	if (kernel_can_power_off()) {
 		if (!reboot_force)
 			machine_shutdown();
+		slaunch_finalize(!reboot_force);
 		do_kernel_power_off();
+	} else {
+		slaunch_finalize(0);
 	}
+
 	/* A fallback in case there is no PM info available */
 	tboot_shutdown(TB_SHUTDOWN_HALT);
 }
@@ -825,6 +838,7 @@ void machine_shutdown(void)
 
 void machine_emergency_restart(void)
 {
+	slaunch_finalize(0);
 	__machine_emergency_restart(1);
 }
 
-- 
2.43.7