KVM: MMU: large page support
Create large pages mappings if the guest PTE's are marked as such and
the underlying memory is hugetlbfs backed. If the largepage contains
write-protected pages, a large pte is not used.
Gives a consistent 2% improvement for data copies on ram mounted
filesystem, without NPT/EPT.
Anthony measures a 4% improvement on 4-way kernbench, with NPT.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 8c3f74b..95473ef 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -39,6 +39,13 @@
#define INVALID_PAGE (~(hpa_t)0)
#define UNMAPPED_GVA (~(gpa_t)0)
+/* shadow tables are PAE even on non-PAE hosts */
+#define KVM_HPAGE_SHIFT 21
+#define KVM_HPAGE_SIZE (1UL << KVM_HPAGE_SHIFT)
+#define KVM_HPAGE_MASK (~(KVM_HPAGE_SIZE - 1))
+
+#define KVM_PAGES_PER_HPAGE (KVM_HPAGE_SIZE / PAGE_SIZE)
+
#define DE_VECTOR 0
#define UD_VECTOR 6
#define NM_VECTOR 7
@@ -230,6 +237,7 @@
struct {
gfn_t gfn; /* presumed gfn during guest pte update */
struct page *page; /* page corresponding to that gfn */
+ int largepage;
} update_pte;
struct i387_fxsave_struct host_fx_image;
@@ -307,6 +315,7 @@
u32 mmu_recycled;
u32 mmu_cache_miss;
u32 remote_tlb_flush;
+ u32 lpages;
};
struct kvm_vcpu_stat {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 994278f..9750bb3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -103,6 +103,10 @@
unsigned long flags;
unsigned long *rmap;
unsigned long *dirty_bitmap;
+ struct {
+ unsigned long rmap_pde;
+ int write_count;
+ } *lpage_info;
unsigned long userspace_addr;
int user_alloc;
};
@@ -169,6 +173,7 @@
int user_alloc);
gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn);
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
+unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn);
void kvm_release_page_clean(struct page *page);
void kvm_release_page_dirty(struct page *page);
int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,