On hotplug, we execute the hardware extension enable sequence.
On unplug, we decache any vcpus that last ran on the exiting cpu, and
execute the hardware extension disable sequence.
Signed-off-by: Avi Kivity <[email protected]>
Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -34,6 +34,7 @@
#include <linux/highmem.h>
#include <linux/file.h>
#include <asm/desc.h>
+#include <linux/cpu.h>
#include "x86_emulate.h"
#include "segment_descriptor.h"
@@ -2038,6 +2039,64 @@ static struct notifier_block kvm_reboot_
.priority = 0,
};
+/*
+ * Make sure that a cpu that is being hot-unplugged does not have any vcpus
+ * cached on it.
+ */
+static void decache_vcpus_on_cpu(int cpu)
+{
+ struct kvm *vm;
+ struct kvm_vcpu *vcpu;
+ int i;
+
+ spin_lock(&kvm_lock);
+ list_for_each_entry(vm, &vm_list, vm_list)
+ for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+ vcpu = &vm->vcpus[i];
+ /*
+ * If the vcpu is locked, then it is running on some
+ * other cpu and therefore it is not cached on the
+ * cpu in question.
+ *
+ * If it's not locked, check the last cpu it executed
+ * on.
+ */
+ if (mutex_trylock(&vcpu->mutex)) {
+ if (vcpu->cpu == cpu) {
+ kvm_arch_ops->vcpu_decache(vcpu);
+ vcpu->cpu = -1;
+ }
+ mutex_unlock(&vcpu->mutex);
+ }
+ }
+ spin_unlock(&kvm_lock);
+}
+
+static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
+ void *v)
+{
+ int cpu = (long)v;
+
+ switch (val) {
+ case CPU_DEAD:
+ case CPU_UP_CANCELED:
+ decache_vcpus_on_cpu(cpu);
+ smp_call_function_single(cpu, kvm_arch_ops->hardware_disable,
+ NULL, 0, 1);
+ break;
+ case CPU_UP_PREPARE:
+ smp_call_function_single(cpu, kvm_arch_ops->hardware_enable,
+ NULL, 0, 1);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block kvm_cpu_notifier = {
+ .notifier_call = kvm_cpu_hotplug,
+ .priority = 20, /* must be > scheduler priority */
+};
+
static __init void kvm_init_debug(void)
{
struct kvm_stats_debugfs_item *p;
@@ -2084,6 +2143,9 @@ int kvm_init_arch(struct kvm_arch_ops *o
return r;
on_each_cpu(kvm_arch_ops->hardware_enable, 0, 0, 1);
+ r = register_cpu_notifier(&kvm_cpu_notifier);
+ if (r)
+ goto out_free_1;
register_reboot_notifier(&kvm_reboot_notifier);
kvm_chardev_ops.owner = module;
@@ -2098,6 +2160,8 @@ int kvm_init_arch(struct kvm_arch_ops *o
out_free:
unregister_reboot_notifier(&kvm_reboot_notifier);
+ unregister_cpu_notifier(&kvm_cpu_notifier);
+out_free_1:
on_each_cpu(kvm_arch_ops->hardware_disable, 0, 0, 1);
kvm_arch_ops->hardware_unsetup();
return r;
Index: linux-2.6/drivers/kvm/kvm.h
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm.h
+++ linux-2.6/drivers/kvm/kvm.h
@@ -341,6 +341,7 @@ struct kvm_arch_ops {
struct kvm_vcpu *(*vcpu_load)(struct kvm_vcpu *vcpu);
void (*vcpu_put)(struct kvm_vcpu *vcpu);
+ void (*vcpu_decache)(struct kvm_vcpu *vcpu);
int (*set_guest_debug)(struct kvm_vcpu *vcpu,
struct kvm_debug_guest *dbg);
Index: linux-2.6/drivers/kvm/svm.c
===================================================================
--- linux-2.6.orig/drivers/kvm/svm.c
+++ linux-2.6/drivers/kvm/svm.c
@@ -609,6 +609,10 @@ static void svm_vcpu_put(struct kvm_vcpu
put_cpu();
}
+static void svm_vcpu_decache(struct kvm_vcpu *vcpu)
+{
+}
+
static void svm_cache_regs(struct kvm_vcpu *vcpu)
{
vcpu->regs[VCPU_REGS_RAX] = vcpu->svm->vmcb->save.rax;
@@ -1677,6 +1681,7 @@ static struct kvm_arch_ops svm_arch_ops
.vcpu_load = svm_vcpu_load,
.vcpu_put = svm_vcpu_put,
+ .vcpu_decache = svm_vcpu_decache,
.set_guest_debug = svm_guest_debug,
.get_msr = svm_get_msr,
Index: linux-2.6/drivers/kvm/vmx.c
===================================================================
--- linux-2.6.orig/drivers/kvm/vmx.c
+++ linux-2.6/drivers/kvm/vmx.c
@@ -250,6 +250,11 @@ static void vmx_vcpu_put(struct kvm_vcpu
put_cpu();
}
+static void vmx_vcpu_decache(struct kvm_vcpu *vcpu)
+{
+ vcpu_clear(vcpu);
+}
+
static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu)
{
return vmcs_readl(GUEST_RFLAGS);
@@ -509,7 +514,7 @@ static __init int vmx_disabled_by_bios(v
return (msr & 5) == 1; /* locked but not enabled */
}
-static __init void hardware_enable(void *garbage)
+static void hardware_enable(void *garbage)
{
int cpu = raw_smp_processor_id();
u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
@@ -2021,6 +2026,7 @@ static struct kvm_arch_ops vmx_arch_ops
.vcpu_load = vmx_vcpu_load,
.vcpu_put = vmx_vcpu_put,
+ .vcpu_decache = vmx_vcpu_decache,
.set_guest_debug = set_guest_debug,
.get_msr = vmx_get_msr,
-
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