KVM paravirt: Add async PF initialization to PV guest.

Enable async PF in a guest if async PF capability is discovered.

Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2 files changed, 98 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 8662ae0a035c..2315398230d1 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -65,6 +65,12 @@ struct kvm_mmu_op_release_pt {
         __u64 pt_phys;
 };
 
+struct kvm_vcpu_pv_apf_data {
+        __u32 reason;
+        __u8 pad[60];
+        __u32 enabled;
+};
+
 #ifdef __KERNEL__
 #include <asm/processor.h>
 
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index e6db17976b82..032d03b6b54a 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -27,16 +27,30 @@
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/hardirq.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
 #include <asm/timer.h>
+#include <asm/cpu.h>
 
 #define MMU_QUEUE_SIZE 1024
 
+static int kvmapf = 1;
+
+static int parse_no_kvmapf(char *arg)
+{
+        kvmapf = 0;
+        return 0;
+}
+
+early_param("no-kvmapf", parse_no_kvmapf);
+
 struct kvm_para_state {
         u8 mmu_queue[MMU_QUEUE_SIZE];
         int mmu_queue_len;
 };
 
 static DEFINE_PER_CPU(struct kvm_para_state, para_state);
+static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
 
 static struct kvm_para_state *kvm_para_state(void)
 {
@@ -231,12 +245,86 @@ static void __init paravirt_ops_setup(void)
 #endif
 }
 
+void __cpuinit kvm_guest_cpu_init(void)
+{
+        if (!kvm_para_available())
+                return;
+
+        if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
+                u64 pa = __pa(&__get_cpu_var(apf_reason));
+
+                wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
+                __get_cpu_var(apf_reason).enabled = 1;
+                printk(KERN_INFO"KVM setup async PF for cpu %d\n",
+                       smp_processor_id());
+        }
+}
+
+static void kvm_pv_disable_apf(void *unused)
+{
+        if (!__get_cpu_var(apf_reason).enabled)
+                return;
+
+        wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
+        __get_cpu_var(apf_reason).enabled = 0;
+
+        printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
+               smp_processor_id());
+}
+
+static int kvm_pv_reboot_notify(struct notifier_block *nb,
+                                unsigned long code, void *unused)
+{
+        if (code == SYS_RESTART)
+                on_each_cpu(kvm_pv_disable_apf, NULL, 1);
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_pv_reboot_nb = {
+        .notifier_call = kvm_pv_reboot_notify,
+};
+
 #ifdef CONFIG_SMP
 static void __init kvm_smp_prepare_boot_cpu(void)
 {
         WARN_ON(kvm_register_clock("primary cpu clock"));
+        kvm_guest_cpu_init();
         native_smp_prepare_boot_cpu();
 }
+
+static void kvm_guest_cpu_online(void *dummy)
+{
+        kvm_guest_cpu_init();
+}
+
+static void kvm_guest_cpu_offline(void *dummy)
+{
+        kvm_pv_disable_apf(NULL);
+}
+
+static int __cpuinit kvm_cpu_notify(struct notifier_block *self,
+                                    unsigned long action, void *hcpu)
+{
+        int cpu = (unsigned long)hcpu;
+        switch (action) {
+        case CPU_ONLINE:
+        case CPU_DOWN_FAILED:
+        case CPU_ONLINE_FROZEN:
+                smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
+                break;
+        case CPU_DOWN_PREPARE:
+        case CPU_DOWN_PREPARE_FROZEN:
+                smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
+                break;
+        default:
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata kvm_cpu_notifier = {
+        .notifier_call  = kvm_cpu_notify,
+};
 #endif
 
 void __init kvm_guest_init(void)
@@ -245,7 +333,11 @@ void __init kvm_guest_init(void)
                 return;
 
         paravirt_ops_setup();
+        register_reboot_notifier(&kvm_pv_reboot_nb);
 #ifdef CONFIG_SMP
         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
+        register_cpu_notifier(&kvm_cpu_notifier);
+#else
+        kvm_guest_cpu_init();
 #endif
 }