KVM: Recalculate mmu pages needed for every memory region change

Instead of incrementally changing the mmu cache size for every memory slot
operation, recalculate it from scratch.  This is simpler and safer.

Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 729573b844e5e860d4d108f68c5889f2d849ebc6..93ecafbfb1b6bfdeb147f671ebecd3b5988e244c 100644 (file)
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -333,26 +333,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
        if (mem->slot >= kvm->nmemslots)
                kvm->nmemslots = mem->slot + 1;
 
+       *memslot = new;
+
        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);
-               }
+               unsigned int nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);
+               kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
        }
 
-       *memslot = new;
-
        kvm_mmu_slot_remove_write_access(kvm, mem->slot);
        kvm_flush_remote_tlbs(kvm);
 

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 4624f3789b9a8df1d6ad490fee317dd564c44455..101cd5377a89716377021baebe68733b14e5ca85 100644 (file)
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -1535,6 +1535,25 @@ nomem:
        return -ENOMEM;
 }
 
+/*
+ * Caculate mmu pages needed for kvm.
+ */
+unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
+{
+       int i;
+       unsigned int nr_mmu_pages;
+       unsigned int  nr_pages = 0;
+
+       for (i = 0; i < kvm->nmemslots; i++)
+               nr_pages += kvm->memslots[i].npages;
+
+       nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000;
+       nr_mmu_pages = max(nr_mmu_pages,
+                       (unsigned int) KVM_MIN_ALLOC_MMU_PAGES);
+
+       return nr_mmu_pages;
+}
+
 #ifdef AUDIT
 
 static const char *audit_msg;

diff --git a/drivers/kvm/x86.h b/drivers/kvm/x86.h
index 90b791bf62879a64471902c33f06878cadcb5295..71f2477d03fd18c9ce258c62ccaaa0bf3c52197d 100644 (file)
--- a/drivers/kvm/x86.h
+++ b/drivers/kvm/x86.h
@@ -236,6 +236,7 @@ void kvm_mmu_set_nonpresent_ptes(u64 trap_pte, u64 notrap_pte);
 int kvm_mmu_reset_context(struct kvm_vcpu *vcpu);
 void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot);
 void kvm_mmu_zap_all(struct kvm *kvm);
+unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm);
 void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages);
 
 enum emulation_result {