[SRU][F/aws][PATCH v2 6/6] x86/kvm: Unify kvm_pv_guest_cpu_reboot() with kvm_guest_cpu_offline()

[Andrea Righi]

From: Vitaly Kuznetsov <vkuznets at redhat.com>

BugLink: https://bugs.launchpad.net/bugs/1920944

Simplify the code by making PV features shutdown happen in one place.

Signed-off-by: Vitaly Kuznetsov <vkuznets at redhat.com>
(backported from http://next.patchew.org/Linux/20210414123544.1060604-1-vkuznets@redhat.com/)
Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
---
 arch/x86/kernel/kvm.c | 42 +++++++++++++++++-------------------------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index af04f51810d1..cdd24da7da21 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -361,31 +361,6 @@ static void kvm_disable_steal_time(void)
 	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 }
 
-static void kvm_pv_guest_cpu_reboot(void *unused)
-{
-	/*
-	 * We disable PV EOI before we load a new kernel by kexec,
-	 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
-	 * New kernel can re-enable when it boots.
-	 */
-	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
-		wrmsrl(MSR_KVM_PV_EOI_EN, 0);
-	kvm_pv_disable_apf();
-	kvm_disable_steal_time();
-}
-
-static int kvm_pv_reboot_notify(struct notifier_block *nb,
-				unsigned long code, void *unused)
-{
-	if (code == SYS_RESTART)
-		on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
-	return NOTIFY_DONE;
-}
-
-static struct notifier_block kvm_pv_reboot_nb = {
-	.notifier_call = kvm_pv_reboot_notify,
-};
-
 static u64 kvm_steal_clock(int cpu)
 {
 	u64 steal;
@@ -631,6 +606,23 @@ static struct syscore_ops kvm_syscore_ops = {
 	.resume		= kvm_resume,
 };
 
+static void kvm_pv_guest_cpu_reboot(void *unused)
+{
+	kvm_guest_cpu_offline(true);
+}
+
+static int kvm_pv_reboot_notify(struct notifier_block *nb,
+				unsigned long code, void *unused)
+{
+	if (code == SYS_RESTART)
+		on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_pv_reboot_nb = {
+	.notifier_call = kvm_pv_reboot_notify,
+};
+
 /*
  * After a PV feature is registered, the host will keep writing to the
  * registered memory location. If the guest happens to shutdown, this memory
-- 
2.30.2