Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754932AbYKMRs3 (ORCPT ); Thu, 13 Nov 2008 12:48:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754319AbYKMRpd (ORCPT ); Thu, 13 Nov 2008 12:45:33 -0500 Received: from mx2.redhat.com ([66.187.237.31]:37304 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753152AbYKMRpU (ORCPT ); Thu, 13 Nov 2008 12:45:20 -0500 From: Eduardo Habkost To: Avi Kivity , Ingo Molnar Cc: "Eric W. Biederman" , Simon Horman , Andrew Morton , Vivek Goyal , Haren Myneni , Andrey Borzenkov , mingo@redhat.com, "Rafael J. Wysocki" , Zachary Amsden , kexec@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Eduardo Habkost Subject: [PATCH 11/11] x86: disable VMX on all CPUs on reboot Date: Thu, 13 Nov 2008 15:43:51 -0200 Message-Id: <1226598231-18311-12-git-send-email-ehabkost@redhat.com> In-Reply-To: <1226598231-18311-1-git-send-email-ehabkost@redhat.com> References: <1226598231-18311-1-git-send-email-ehabkost@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4046 Lines: 139 On emergency_restart, we may need to use an NMI to disable virtualization on all CPUs. We do that using nmi_shootdown_cpus() if VMX is enabled. Finding a proper point to hook the nmi_shootdown_cpus() call isn't trivial, as the non-emergency machine_restart() (that doesn't need the NMI tricks) uses machine_emergency_restart() directly. The solution to make this work without adding a new function or argument to machine_ops was setting a 'reboot_emergency' flag that tells if native_machine_emergency_restart() needs to do the virt cleanup or not. Signed-off-by: Eduardo Habkost --- arch/x86/kernel/reboot.c | 63 ++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 61 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 6f05a28..a5f8c09 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -12,6 +12,7 @@ #include #include #include +#include #ifdef CONFIG_X86_32 # include @@ -39,6 +40,13 @@ int reboot_force; static int reboot_cpu = -1; #endif +/* This is set if we need to go through the 'emergency' path. + * When machine_emergency_restart() is called, we may be on + * an inconsistent state and won't be able to do a clean cleanup + */ +static int reboot_emergency; + + /* This is set by the PCI code if either type 1 or type 2 PCI is detected */ bool port_cf9_safe = false; @@ -359,6 +367,48 @@ static inline void kb_wait(void) } } +static void vmxoff_nmi(int cpu, struct die_args *args) +{ + cpu_emergency_vmxoff(); +} + +/* Use NMIs as IPIs to tell all CPUs to disable virtualization + */ +static void emergency_vmx_disable_all(void) +{ + /* Just make sure we won't change CPUs while doing this */ + local_irq_disable(); + + /* We need to disable VMX on all CPUs before rebooting, otherwise + * we risk hanging up the machine, because the CPU ignore INIT + * signals when VMX is enabled. + * + * We can't take any locks and we may be on an inconsistent + * state, so we use NMIs as IPIs to tell the other CPUs to disable + * VMX and halt. + * + * For safety, we will avoid running the nmi_shootdown_cpus() + * stuff unnecessarily, but we don't have a way to check + * if other CPUs have VMX enabled. So we will call it only if the + * CPU we are running on has VMX enabled. + * + * We will miss cases where VMX is not enabled on all CPUs. This + * shouldn't do much harm because KVM always enable VMX on all + * CPUs anyway. But we can miss it on the small window where KVM + * is still enabling VMX. + */ + if (cpu_has_vmx() && cpu_vmx_enabled()) { + /* Disable VMX on this CPU. + */ + cpu_vmxoff(); + + /* Halt and disable VMX on the other CPUs */ + nmi_shootdown_cpus(vmxoff_nmi); + + } +} + + void __attribute__((weak)) mach_reboot_fixups(void) { } @@ -367,6 +417,9 @@ static void native_machine_emergency_restart(void) { int i; + if (reboot_emergency) + emergency_vmx_disable_all(); + /* Tell the BIOS if we want cold or warm reboot */ *((unsigned short *)__va(0x472)) = reboot_mode; @@ -473,13 +526,19 @@ void native_machine_shutdown(void) #endif } +static void __machine_emergency_restart(int emergency) +{ + reboot_emergency = emergency; + machine_ops.emergency_restart(); +} + static void native_machine_restart(char *__unused) { printk("machine restart\n"); if (!reboot_force) machine_shutdown(); - machine_emergency_restart(); + __machine_emergency_restart(0); } static void native_machine_halt(void) @@ -523,7 +582,7 @@ void machine_shutdown(void) void machine_emergency_restart(void) { - machine_ops.emergency_restart(); + __machine_emergency_restart(1); } void machine_restart(char *cmd) -- 1.5.5.GIT -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/