KVM: Synchronize guest physical memory map to host virtual memory map

Synchronize changes to host virtual addresses which are part of
a KVM memory slot to the KVM shadow mmu.  This allows pte operations
like swapping, page migration, and madvise() to transparently work
with KVM.

Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 30 insertions, 0 deletions

diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index bc34dc21f178..0f3c53114614 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -13,6 +13,7 @@
 
 #include <linux/types.h>
 #include <linux/mm.h>
+#include <linux/mmu_notifier.h>
 
 #include <linux/kvm.h>
 #include <linux/kvm_para.h>
@@ -251,6 +252,7 @@ struct kvm_vcpu_arch {
                 gfn_t gfn;      /* presumed gfn during guest pte update */
                 pfn_t pfn;      /* pfn corresponding to that gfn */
                 int largepage;
+                unsigned long mmu_seq;
         } update_pte;
 
         struct i387_fxsave_struct host_fx_image;
@@ -729,4 +731,8 @@ asmlinkage void kvm_handle_fault_on_reboot(void);
         KVM_EX_ENTRY " 666b, 667b \n\t" \
         ".popsection"
 
+#define KVM_ARCH_WANT_MMU_NOTIFIER
+int kvm_unmap_hva(struct kvm *kvm, unsigned long hva);
+int kvm_age_hva(struct kvm *kvm, unsigned long hva);
+
 #endif
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 07d68a8ae8e9..8525afc53107 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -121,6 +121,12 @@ struct kvm {
         struct kvm_coalesced_mmio_dev *coalesced_mmio_dev;
         struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;
 #endif
+
+#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
+        struct mmu_notifier mmu_notifier;
+        unsigned long mmu_notifier_seq;
+        long mmu_notifier_count;
+#endif
 };
 
 /* The guest did something we don't support. */
@@ -332,4 +338,22 @@ int kvm_trace_ioctl(unsigned int ioctl, unsigned long arg)
 #define kvm_trace_cleanup() ((void)0)
 #endif
 
+#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
+static inline int mmu_notifier_retry(struct kvm_vcpu *vcpu, unsigned long mmu_seq)
+{
+        if (unlikely(vcpu->kvm->mmu_notifier_count))
+                return 1;
+        /*
+         * Both reads happen under the mmu_lock and both values are
+         * modified under mmu_lock, so there's no need of smb_rmb()
+         * here in between, otherwise mmu_notifier_count should be
+         * read before mmu_notifier_seq, see
+         * mmu_notifier_invalidate_range_end write side.
+         */
+        if (vcpu->kvm->mmu_notifier_seq != mmu_seq)
+                return 1;
+        return 0;
+}
+#endif
+
 #endif