Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e4ce333c authored by Sean Christopherson's avatar Sean Christopherson Committed by Greg Kroah-Hartman
Browse files

x86/reboot: Disable SVM, not just VMX, when stopping CPUs 



commit a2b07fa7b93321c059af0c6d492cc9a4f1e390aa upstream.

Disable SVM and more importantly force GIF=1 when halting a CPU or
rebooting the machine.  Similar to VMX, SVM allows software to block
INITs via CLGI, and thus can be problematic for a crash/reboot.  The
window for failure is smaller with SVM as INIT is only blocked while
GIF=0, i.e. between CLGI and STGI, but the window does exist.

Fixes: fba4f472 ("x86/reboot: Turn off KVM when halting a CPU")
Cc: stable@vger.kernel.org
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20221130233650.1404148-5-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 37459195

arch/x86/kernel/smp.c

+3 −3
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ 
#include <asm/mce.h>

#include <asm/trace/irq_vectors.h>

#include <asm/kexec.h>

#include <asm/virtext.h>

#include <asm/reboot.h>



/*

 *	Some notes on x86 processor bugs affecting SMP operation:
@@ -121,7 +121,7 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs) 
	if (raw_smp_processor_id() == atomic_read(&stopping_cpu))

		return NMI_HANDLED;



	cpu_emergency_vmxoff();

	cpu_emergency_disable_virtualization();

	stop_this_cpu(NULL);



	return NMI_HANDLED;
@@ -134,7 +134,7 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs) 
asmlinkage __visible void smp_reboot_interrupt(void)

{

	ipi_entering_ack_irq();

	cpu_emergency_vmxoff();

	cpu_emergency_disable_virtualization();

	stop_this_cpu(NULL);

	irq_exit();

}