s390/mm: extended gmap pte notifier

The current gmap pte notifier forces a pte into to a read-write state.
If the pte is invalidated the gmap notifier is called to inform KVM
that the mapping will go away.

Extend this approach to allow read-write, read-only and no-access
as possible target states and call the pte notifier for any change
to the pte.

This mechanism is used to temporarily set specific access rights for
a pte without doing the heavy work of a true mprotect call.

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

1 files changed, 7 insertions, 6 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 67f1b6b4c060..b6e7f66f0f01 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -21,6 +21,7 @@
 #include <linux/init.h>
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
+#include <linux/mman.h>
 #include <linux/module.h>
 #include <linux/random.h>
 #include <linux/slab.h>
@@ -185,7 +186,7 @@ static struct notifier_block kvm_clock_notifier = {
 int kvm_arch_hardware_setup(void)
 {
         gmap_notifier.notifier_call = kvm_gmap_notifier;
-        gmap_register_ipte_notifier(&gmap_notifier);
+        gmap_register_pte_notifier(&gmap_notifier);
         atomic_notifier_chain_register(&s390_epoch_delta_notifier,
                                        &kvm_clock_notifier);
         return 0;
@@ -193,7 +194,7 @@ int kvm_arch_hardware_setup(void)
 
 void kvm_arch_hardware_unsetup(void)
 {
-        gmap_unregister_ipte_notifier(&gmap_notifier);
+        gmap_unregister_pte_notifier(&gmap_notifier);
         atomic_notifier_chain_unregister(&s390_epoch_delta_notifier,
                                          &kvm_clock_notifier);
 }
@@ -2272,16 +2273,16 @@ retry:
                 return 0;
         /*
          * We use MMU_RELOAD just to re-arm the ipte notifier for the
-         * guest prefix page. gmap_ipte_notify will wait on the ptl lock.
+         * guest prefix page. gmap_mprotect_notify will wait on the ptl lock.
          * This ensures that the ipte instruction for this request has
          * already finished. We might race against a second unmapper that
          * wants to set the blocking bit. Lets just retry the request loop.
          */
         if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu)) {
                 int rc;
-                rc = gmap_ipte_notify(vcpu->arch.gmap,
-                                      kvm_s390_get_prefix(vcpu),
-                                      PAGE_SIZE * 2);
+                rc = gmap_mprotect_notify(vcpu->arch.gmap,
+                                          kvm_s390_get_prefix(vcpu),
+                                          PAGE_SIZE * 2, PROT_WRITE);
                 if (rc)
                         return rc;
                 goto retry;