On Thu, 2013-01-03 at 11:41 -0200, Marcelo Tosatti wrote:
> Andy, Mike, can you confirm whether this fixes the percpu allocation
> failures when loading kvm.ko? TIA
monteverdi:~/:[1]# dmesg|grep PERCPU
[ 0.000000] PERCPU: Embedded 27 pages/cpu @ffff88047f800000 s80704 r8192
d21696 u262144
monteverdi:~/:[0]# lsmod|grep kvm
kvm_intel 132688 0
kvm 423692 1 kvm_intel
monteverdi:~/:[0]# uname -r
3.6.0-bisect
Yup, kvm loaded itself, no gripeage.
> ----
>
> Use dynamic percpu allocations for the shared msrs structure,
> to avoid using the limited reserved percpu space.
>
> Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1c9c834..5229a67 100644
> --- 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)
--
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