From: Sasha Levin Subject: [PATCH AUTOSEL for 4.9 052/190] x86/reboot: Turn off KVM when halting a CPU Date: Thu, 8 Mar 2018 04:59:14 +0000 Message-ID: <20180308045810.8041-52-alexander.levin@microsoft.com> References: <20180308045810.8041-1-alexander.levin@microsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: Tiantian Feng , Xishi Qiu , Paolo Bonzini , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , "kvm@vger.kernel.org" , Ingo Molnar , Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Return-path: In-Reply-To: <20180308045810.8041-1-alexander.levin@microsoft.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org From: Tiantian Feng [ Upstream commit fba4f472b33aa81ca1836f57d005455261e9126f ] A CPU in VMX root mode will ignore INIT signals and will fail to bring up the APs after reboot. Therefore, on a panic we disable VMX on all CPUs before rebooting or triggering kdump. Do this when halting the machine as well, in case a firmware-level reboot does not perform a cold reset for all processors. Without doing this, rebooting the host may hang. Signed-off-by: Tiantian Feng Signed-off-by: Xishi Qiu [ Rewritten commit message. ] Signed-off-by: Paolo Bonzini Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: kvm@vger.kernel.org Link: http://lkml.kernel.org/r/20170419161839.30550-1-pbonzini@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- arch/x86/kernel/smp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index ca699677e288..ea217caa731c 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -33,6 +33,7 @@ #include #include #include +#include =20 /* * Some notes on x86 processor bugs affecting SMP operation: @@ -162,6 +163,7 @@ static int smp_stop_nmi_callback(unsigned int val, stru= ct pt_regs *regs) if (raw_smp_processor_id() =3D=3D atomic_read(&stopping_cpu)) return NMI_HANDLED; =20 + cpu_emergency_vmxoff(); stop_this_cpu(NULL); =20 return NMI_HANDLED; @@ -174,6 +176,7 @@ static int smp_stop_nmi_callback(unsigned int val, stru= ct pt_regs *regs) asmlinkage __visible void smp_reboot_interrupt(void) { ipi_entering_ack_irq(); + cpu_emergency_vmxoff(); stop_this_cpu(NULL); irq_exit(); } --=20 2.14.1