The current kvm implementation keeps EL2 vector table installed even
when the system is shut down. This prevents kexec from putting the system
with kvm back into EL2 when starting a new kernel.
This patch resolves this issue by calling a cpu tear-down function via
reboot notifier, kvm_reboot_notify(), which is invoked by
kernel_restart_prepare() in kernel_kexec().
While kvm has a generic hook, kvm_reboot(), we can't use it here because
a cpu teardown function will not be invoked, under current implementation,
if no guest vm has been created by kvm_create_vm().
Please note that kvm_usage_count is zero in this case.
We'd better, in the future, implement cpu hotplug support and put the
arch-specific initialization into kvm_arch_hardware_enable/disable().
This way, we would be able to revert this patch.
Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
arch/arm/kvm/arm.c | 21 +++++++++++++++++++++
arch/arm64/kvm/Kconfig | 1 -
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 39df694..f64713e 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -25,6 +25,7 @@
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/mman.h>
+#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/kvm.h>
#include <trace/events/kvm.h>
@@ -1100,6 +1101,23 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr)
return NULL;
}
+static int kvm_reboot_notify(struct notifier_block *nb,
+ unsigned long val, void *v)
+{
+ /*
+ * Reset each CPU in EL2 to initial state.
+ */
+ on_each_cpu(kvm_cpu_reset, NULL, 1);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_reboot_nb = {
+ .notifier_call = kvm_reboot_notify,
+ .next = NULL,
+ .priority = 0, /* FIXME */
+};
+
/**
* Initialize Hyp-mode and memory mappings on all CPUs.
*/
@@ -1138,6 +1156,9 @@ int kvm_arch_init(void *opaque)
hyp_cpu_pm_init();
kvm_coproc_table_init();
+
+ register_reboot_notifier(&kvm_reboot_nb);
+
return 0;
out_err:
cpu_notifier_register_done();
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 30ae7a7..f5590c8 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -18,7 +18,6 @@ if VIRTUALIZATION
config KVM
bool "Kernel-based Virtual Machine (KVM) support"
- depends on !KEXEC
select MMU_NOTIFIER
select PREEMPT_NOTIFIERS
select ANON_INODES
--
1.7.9.5
