From: Sean Christopherson seanjc@google.com
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: fba4f472b33a ("x86/reboot: Turn off KVM when halting a CPU") Cc: stable@vger.kernel.org Reviewed-by: Thomas Gleixner tglx@linutronix.de Link: https://lore.kernel.org/r/20221130233650.1404148-5-seanjc@google.com Signed-off-by: Sean Christopherson seanjc@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/smp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -32,7 +32,7 @@ #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: @@ -122,7 +122,7 @@ static int smp_stop_nmi_callback(unsigne 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(unsigne DEFINE_IDTENTRY_SYSVEC(sysvec_reboot) { ack_APIC_irq(); - cpu_emergency_vmxoff(); + cpu_emergency_disable_virtualization(); stop_this_cpu(NULL); }