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Diffstat (limited to 'arch/x86/kernel/kvm.c')
-rw-r--r--arch/x86/kernel/kvm.c64
1 files changed, 61 insertions, 3 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index e554e5ad2fe8..c1d61ee4b4f1 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -39,6 +39,9 @@
#include <asm/desc.h>
#include <asm/tlbflush.h>
#include <asm/idle.h>
+#include <asm/apic.h>
+#include <asm/apicdef.h>
+#include <asm/hypervisor.h>
static int kvmapf = 1;
@@ -283,6 +286,22 @@ static void kvm_register_steal_time(void)
cpu, __pa(st));
}
+static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
+
+static void kvm_guest_apic_eoi_write(u32 reg, u32 val)
+{
+ /**
+ * This relies on __test_and_clear_bit to modify the memory
+ * in a way that is atomic with respect to the local CPU.
+ * The hypervisor only accesses this memory from the local CPU so
+ * there's no need for lock or memory barriers.
+ * An optimization barrier is implied in apic write.
+ */
+ if (__test_and_clear_bit(KVM_PV_EOI_BIT, &__get_cpu_var(kvm_apic_eoi)))
+ return;
+ apic_write(APIC_EOI, APIC_EOI_ACK);
+}
+
void __cpuinit kvm_guest_cpu_init(void)
{
if (!kvm_para_available())
@@ -300,11 +319,20 @@ void __cpuinit kvm_guest_cpu_init(void)
smp_processor_id());
}
+ if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
+ unsigned long pa;
+ /* Size alignment is implied but just to make it explicit. */
+ BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
+ __get_cpu_var(kvm_apic_eoi) = 0;
+ pa = __pa(&__get_cpu_var(kvm_apic_eoi)) | KVM_MSR_ENABLED;
+ wrmsrl(MSR_KVM_PV_EOI_EN, pa);
+ }
+
if (has_steal_clock)
kvm_register_steal_time();
}
-static void kvm_pv_disable_apf(void *unused)
+static void kvm_pv_disable_apf(void)
{
if (!__get_cpu_var(apf_reason).enabled)
return;
@@ -316,11 +344,23 @@ static void kvm_pv_disable_apf(void *unused)
smp_processor_id());
}
+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();
+}
+
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);
+ on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
return NOTIFY_DONE;
}
@@ -371,7 +411,9 @@ static void __cpuinit kvm_guest_cpu_online(void *dummy)
static void kvm_guest_cpu_offline(void *dummy)
{
kvm_disable_steal_time();
- kvm_pv_disable_apf(NULL);
+ if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
+ wrmsrl(MSR_KVM_PV_EOI_EN, 0);
+ kvm_pv_disable_apf();
apf_task_wake_all();
}
@@ -424,6 +466,9 @@ void __init kvm_guest_init(void)
pv_time_ops.steal_clock = kvm_steal_clock;
}
+ if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
+ apic_set_eoi_write(kvm_guest_apic_eoi_write);
+
#ifdef CONFIG_SMP
smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
register_cpu_notifier(&kvm_cpu_notifier);
@@ -432,6 +477,19 @@ void __init kvm_guest_init(void)
#endif
}
+static bool __init kvm_detect(void)
+{
+ if (!kvm_para_available())
+ return false;
+ return true;
+}
+
+const struct hypervisor_x86 x86_hyper_kvm __refconst = {
+ .name = "KVM",
+ .detect = kvm_detect,
+};
+EXPORT_SYMBOL_GPL(x86_hyper_kvm);
+
static __init int activate_jump_labels(void)
{
if (has_steal_clock) {