commit e930bffe95e1e886a1ede80726ea38df5838d067
author Andrea Arcangeli <andrea@qumranet.com> Fri Jul 25 16:24:52 2008 +0200
committer Avi Kivity <avi@qumranet.com> Tue Jul 29 12:33:53 2008 +0300
tree d39227c3de8e7d4a70737c78693f6d7f458066af
parent 604b38ac0369bd50fcbb33344aa5553c071009f7

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>

arch/x86/kvm/paging_tmpl.h

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 4d91822..f72ac1f 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -263,6 +263,8 @@
 	pfn = vcpu->arch.update_pte.pfn;
 	if (is_error_pfn(pfn))
 		return;
+	if (mmu_notifier_retry(vcpu, vcpu->arch.update_pte.mmu_seq))
+		return;
 	kvm_get_pfn(pfn);
 	mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
 		     gpte & PT_DIRTY_MASK, NULL, largepage, gpte_to_gfn(gpte),
@@ -380,6 +382,7 @@
 	int r;
 	pfn_t pfn;
 	int largepage = 0;
+	unsigned long mmu_seq;
 
 	pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
 	kvm_mmu_audit(vcpu, "pre page fault");
@@ -413,6 +416,8 @@
 			largepage = 1;
 		}
 	}
+	mmu_seq = vcpu->kvm->mmu_notifier_seq;
+	/* implicit mb(), we'll read before PT lock is unlocked */
 	pfn = gfn_to_pfn(vcpu->kvm, walker.gfn);
 	up_read(&current->mm->mmap_sem);
 
@@ -424,6 +429,8 @@
 	}
 
 	spin_lock(&vcpu->kvm->mmu_lock);
+	if (mmu_notifier_retry(vcpu, mmu_seq))
+		goto out_unlock;
 	kvm_mmu_free_some_pages(vcpu);
 	shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
 				  largepage, &write_pt, pfn);
@@ -439,6 +446,11 @@
 	spin_unlock(&vcpu->kvm->mmu_lock);
 
 	return write_pt;
+
+out_unlock:
+	spin_unlock(&vcpu->kvm->mmu_lock);
+	kvm_release_pfn_clean(pfn);
+	return 0;
 }
 
 static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)