KVM: x86: use dynamic percpu allocations for shared msrs area

Use dynamic percpu allocations for the shared msrs structure,
to avoid using the limited reserved percpu space.

Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 76f5446..c243b81 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -120,7 +120,7 @@ struct kvm_shared_msrs {
 };
 
 static struct kvm_shared_msrs_global __read_mostly shared_msrs_global;
-static DEFINE_PER_CPU(struct kvm_shared_msrs, shared_msrs);
+static struct kvm_shared_msrs __percpu *shared_msrs;
 
 struct kvm_stats_debugfs_item debugfs_entries[] = {
        { "pf_fixed", VCPU_STAT(pf_fixed) },
@@ -191,10 +191,10 @@ static void kvm_on_user_return(struct user_return_notifier *urn)
 
 static void shared_msr_update(unsigned slot, u32 msr)
 {
-       struct kvm_shared_msrs *smsr;
        u64 value;
+       unsigned int cpu = smp_processor_id();
+       struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
 
-       smsr = &__get_cpu_var(shared_msrs);
        /* only read, and nobody should modify it at this time,
         * so don't need lock */
        if (slot >= shared_msrs_global.nr) {
@@ -226,7 +226,8 @@ static void kvm_shared_msr_cpu_online(void)
 
 void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask)
 {
-       struct kvm_shared_msrs *smsr = &__get_cpu_var(shared_msrs);
+       unsigned int cpu = smp_processor_id();
+       struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
 
        if (((value ^ smsr->values[slot].curr) & mask) == 0)
                return;
@@ -242,7 +243,8 @@ EXPORT_SYMBOL_GPL(kvm_set_shared_msr);
 
 static void drop_user_return_notifiers(void *ignore)
 {
-       struct kvm_shared_msrs *smsr = &__get_cpu_var(shared_msrs);
+       unsigned int cpu = smp_processor_id();
+       struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu);
 
        if (smsr->registered)
                kvm_on_user_return(&smsr->urn);
@@ -5233,9 +5235,16 @@ int kvm_arch_init(void *opaque)
                goto out;
        }
 
+       r = -ENOMEM;
+       shared_msrs = alloc_percpu(struct kvm_shared_msrs);
+       if (!shared_msrs) {
+               printk(KERN_ERR "kvm: failed to allocate percpu kvm_shared_msrs\n");
+               goto out;
+       }
+
        r = kvm_mmu_module_init();
        if (r)
-               goto out;
+               goto out_free_percpu;
 
        kvm_set_mmio_spte_mask();
        kvm_init_msr_list();
@@ -5258,6 +5267,8 @@ int kvm_arch_init(void *opaque)
 
        return 0;
 
+out_free_percpu:
+       free_percpu(shared_msrs);
 out:
        return r;
 }
@@ -5275,6 +5286,7 @@ void kvm_arch_exit(void)
 #endif
        kvm_x86_ops = NULL;
        kvm_mmu_module_exit();
+       free_percpu(shared_msrs);
 }
 
 int kvm_emulate_halt(struct kvm_vcpu *vcpu)