KVM: Allow dynamic allocation of the mmu shadow cache size

The user is now able to set how many mmu pages will be allocated to the guest.

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index cac328b8421c..2bb1f2f66efa 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -743,6 +743,24 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
         if (mem->slot >= kvm->nmemslots)
                 kvm->nmemslots = mem->slot + 1;
 
+        if (!kvm->n_requested_mmu_pages) {
+                unsigned int n_pages;
+
+                if (npages) {
+                        n_pages = npages * KVM_PERMILLE_MMU_PAGES / 1000;
+                        kvm_mmu_change_mmu_pages(kvm, kvm->n_alloc_mmu_pages +
+                                                 n_pages);
+                } else {
+                        unsigned int nr_mmu_pages;
+
+                        n_pages = old.npages * KVM_PERMILLE_MMU_PAGES / 1000;
+                        nr_mmu_pages = kvm->n_alloc_mmu_pages - n_pages;
+                        nr_mmu_pages = max(nr_mmu_pages,
+                                        (unsigned int) KVM_MIN_ALLOC_MMU_PAGES);
+                        kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
+                }
+        }
+
         *memslot = new;
 
         kvm_mmu_slot_remove_write_access(kvm, mem->slot);
@@ -760,6 +778,26 @@ out:
         return r;
 }
 
+static int kvm_vm_ioctl_set_nr_mmu_pages(struct kvm *kvm,
+                                          u32 kvm_nr_mmu_pages)
+{
+        if (kvm_nr_mmu_pages < KVM_MIN_ALLOC_MMU_PAGES)
+                return -EINVAL;
+
+        mutex_lock(&kvm->lock);
+
+        kvm_mmu_change_mmu_pages(kvm, kvm_nr_mmu_pages);
+        kvm->n_requested_mmu_pages = kvm_nr_mmu_pages;
+
+        mutex_unlock(&kvm->lock);
+        return 0;
+}
+
+static int kvm_vm_ioctl_get_nr_mmu_pages(struct kvm *kvm)
+{
+        return kvm->n_alloc_mmu_pages;
+}
+
 /*
  * Get (and clear) the dirty memory log for a memory slot.
  */
@@ -3071,6 +3109,14 @@ static long kvm_vm_ioctl(struct file *filp,
                         goto out;
                 break;
         }
+        case KVM_SET_NR_MMU_PAGES:
+                r = kvm_vm_ioctl_set_nr_mmu_pages(kvm, arg);
+                if (r)
+                        goto out;
+                break;
+        case KVM_GET_NR_MMU_PAGES:
+                r = kvm_vm_ioctl_get_nr_mmu_pages(kvm);
+                break;
         case KVM_GET_DIRTY_LOG: {
                 struct kvm_dirty_log log;
 
@@ -3278,6 +3324,7 @@ static long kvm_dev_ioctl(struct file *filp,
                 switch (ext) {
                 case KVM_CAP_IRQCHIP:
                 case KVM_CAP_HLT:
+                case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
                         r = 1;
                         break;
                 default: