KVM: s390: randomize sca address

We allocate a page for the 2k sca, so lets use the space to improve
hit rate of some internal cpu caches. No need to change the freeing
of the page, as this will shift away the page offset bits anyway.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 7337c57..a02979f 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -215,6 +215,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
        int rc;
        char debug_name[16];
+       static unsigned long sca_offset;
 
        rc = -EINVAL;
 #ifdef CONFIG_KVM_S390_UCONTROL
@@ -236,6 +237,10 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
        kvm->arch.sca = (struct sca_block *) get_zeroed_page(GFP_KERNEL);
        if (!kvm->arch.sca)
                goto out_err;
+       spin_lock(&kvm_lock);
+       sca_offset = (sca_offset + 16) & 0x7f0;
+       kvm->arch.sca = (struct sca_block *) ((char *) kvm->arch.sca + sca_offset);
+       spin_unlock(&kvm_lock);
 
        sprintf(debug_name, "kvm-%u", current->pid);