On Thu, Apr 02, 2015 at 06:40:13AM +0100, AKASHI Takahiro wrote:
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.
Why can't we use kvm_arch_hardware_enable/disable() currently?
Signed-off-by: AKASHI Takahiro takahiro.akashi@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 */
It would be helpful for the comment to explain why this is wrong, and what needs fixing.
Mark.