this is needed for kvm if it want ksm to directly map pages into its
shadow page tables.

Signed-off-by: Izik Eidus <iei...@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |    1 +
 arch/x86/kvm/mmu.c              |   68 +++++++++++++++++++++++++++++++++++----
 virt/kvm/kvm_main.c             |   14 ++++++++
 3 files changed, 76 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8351c4d..9062729 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -791,5 +791,6 @@ asmlinkage void kvm_handle_fault_on_reboot(void);
 #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);
+void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
 
 #endif /* _ASM_X86_KVM_HOST_H */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 6b4d795..f8816dd 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -257,6 +257,11 @@ static pfn_t spte_to_pfn(u64 pte)
        return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
 }
 
+static pte_t ptep_val(pte_t *ptep)
+{
+       return *ptep;
+}
+
 static gfn_t pse36_gfn_delta(u32 gpte)
 {
        int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT;
@@ -678,7 +683,8 @@ static int rmap_write_protect(struct kvm *kvm, u64 gfn)
        return write_protected;
 }
 
-static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp)
+static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
+                          unsigned long data)
 {
        u64 *spte;
        int need_tlb_flush = 0;
@@ -693,8 +699,48 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long 
*rmapp)
        return need_tlb_flush;
 }
 
+static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
+                            unsigned long data)
+{
+       int need_flush = 0;
+       u64 *spte, new_spte;
+       pte_t *ptep = (pte_t *)data;
+       pfn_t new_pfn;
+
+       new_pfn = pte_pfn(ptep_val(ptep));
+       spte = rmap_next(kvm, rmapp, NULL);
+       while (spte) {
+               BUG_ON(!is_shadow_present_pte(*spte));
+               rmap_printk("kvm_set_pte_rmapp: spte %p %llx\n", spte, *spte);
+               need_flush = 1;
+               if (pte_write(ptep_val(ptep))) {
+                       rmap_remove(kvm, spte);
+                       set_shadow_pte(spte, shadow_trap_nonpresent_pte);
+                       spte = rmap_next(kvm, rmapp, NULL);
+               } else {
+                       new_spte = *spte &~ (PT64_BASE_ADDR_MASK);
+                       new_spte |= new_pfn << PAGE_SHIFT;
+
+                       if (!pte_write(ptep_val(ptep))) {
+                               new_spte &= ~PT_WRITABLE_MASK;
+                               new_spte &= ~SPTE_HOST_WRITEABLE;
+                               if (is_writeble_pte(*spte))
+                                       kvm_set_pfn_dirty(spte_to_pfn(*spte));
+                       }
+                       set_shadow_pte(spte, new_spte);
+                       spte = rmap_next(kvm, rmapp, spte);
+               }
+       }
+       if (need_flush)
+               kvm_flush_remote_tlbs(kvm);
+
+       return 0;
+}
+
 static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
-                         int (*handler)(struct kvm *kvm, unsigned long *rmapp))
+                         unsigned long data,
+                         int (*handler)(struct kvm *kvm, unsigned long *rmapp,
+                                        unsigned long data))
 {
        int i;
        int retval = 0;
@@ -715,11 +761,13 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long 
hva,
                end = start + (memslot->npages << PAGE_SHIFT);
                if (hva >= start && hva < end) {
                        gfn_t gfn_offset = (hva - start) >> PAGE_SHIFT;
-                       retval |= handler(kvm, &memslot->rmap[gfn_offset]);
+                       retval |= handler(kvm, &memslot->rmap[gfn_offset],
+                                         data);
                        retval |= handler(kvm,
                                          &memslot->lpage_info[
                                                  gfn_offset /
-                                                 
KVM_PAGES_PER_HPAGE].rmap_pde);
+                                                 KVM_PAGES_PER_HPAGE].rmap_pde,
+                                                 data);
                }
        }
 
@@ -728,10 +776,16 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long 
hva,
 
 int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)
 {
-       return kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
+       return kvm_handle_hva(kvm, hva, 0, kvm_unmap_rmapp);
+}
+
+void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
+{
+       kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
 }
 
-static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp)
+static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
+                        unsigned long data)
 {
        u64 *spte;
        int young = 0;
@@ -757,7 +811,7 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long 
*rmapp)
 
 int kvm_age_hva(struct kvm *kvm, unsigned long hva)
 {
-       return kvm_handle_hva(kvm, hva, kvm_age_rmapp);
+       return kvm_handle_hva(kvm, hva, 0, kvm_age_rmapp);
 }
 
 #ifdef MMU_DEBUG
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8aa3b95..3d340e9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -846,6 +846,19 @@ static void kvm_mmu_notifier_invalidate_page(struct 
mmu_notifier *mn,
 
 }
 
+static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
+                                       struct mm_struct *mm,
+                                       unsigned long address,
+                                       pte_t pte)
+{
+       struct kvm *kvm = mmu_notifier_to_kvm(mn);
+
+       spin_lock(&kvm->mmu_lock);
+       kvm->mmu_notifier_seq++;
+       kvm_set_spte_hva(kvm, address, pte);
+       spin_unlock(&kvm->mmu_lock);
+}
+
 static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
                                                    struct mm_struct *mm,
                                                    unsigned long start,
@@ -925,6 +938,7 @@ static const struct mmu_notifier_ops kvm_mmu_notifier_ops = 
{
        .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start,
        .invalidate_range_end   = kvm_mmu_notifier_invalidate_range_end,
        .clear_flush_young      = kvm_mmu_notifier_clear_flush_young,
+       .change_pte             = kvm_mmu_notifier_change_pte,
        .release                = kvm_mmu_notifier_release,
 };
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
-- 
1.5.6.5

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