[patch 3/4] KVM: MMU: reload request from GET_DIRTY_LOG path

[mtosatti@xxxxxxxxxx]

Reload remote vcpus MMU from GET_DIRTY_LOG codepath, before
deleting a pinned spte.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

---
 arch/x86/kvm/mmu.c |   29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

Index: kvm.pinned-sptes/arch/x86/kvm/mmu.c
===================================================================
--- kvm.pinned-sptes.orig/arch/x86/kvm/mmu.c	2014-07-09 11:23:59.290744490 -0300
+++ kvm.pinned-sptes/arch/x86/kvm/mmu.c	2014-07-09 11:24:58.449632435 -0300
@@ -1208,7 +1208,8 @@
  *
  * Return true if tlb need be flushed.
  */
-static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool pt_protect)
+static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool pt_protect,
+			       bool skip_pinned)
 {
 	u64 spte = *sptep;
 
@@ -1218,6 +1219,22 @@
 
 	rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
 
+	if (is_pinned_spte(spte)) {
+		/* keep pinned spte intact, mark page dirty again */
+		if (skip_pinned) {
+			struct kvm_mmu_page *sp;
+			gfn_t gfn;
+
+			sp = page_header(__pa(sptep));
+			gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
+
+			mark_page_dirty(kvm, gfn);
+			return false;
+		} else
+			mmu_reload_pinned_vcpus(kvm);
+	}
+
+
 	if (pt_protect)
 		spte &= ~SPTE_MMU_WRITEABLE;
 	spte = spte & ~PT_WRITABLE_MASK;
@@ -1226,7 +1243,7 @@
 }
 
 static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
-				 bool pt_protect)
+				 bool pt_protect, bool skip_pinned)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
@@ -1235,7 +1252,7 @@
 	for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
 		BUG_ON(!(*sptep & PT_PRESENT_MASK));
 
-		flush |= spte_write_protect(kvm, sptep, pt_protect);
+		flush |= spte_write_protect(kvm, sptep, pt_protect, skip_pinned);
 		sptep = rmap_get_next(&iter);
 	}
 
@@ -1261,7 +1278,7 @@
 	while (mask) {
 		rmapp = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
 				      PT_PAGE_TABLE_LEVEL, slot);
-		__rmap_write_protect(kvm, rmapp, false);
+		__rmap_write_protect(kvm, rmapp, false, true);
 
 		/* clear the first set bit */
 		mask &= mask - 1;
@@ -1280,7 +1297,7 @@
 	for (i = PT_PAGE_TABLE_LEVEL;
 	     i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
 		rmapp = __gfn_to_rmap(gfn, i, slot);
-		write_protected |= __rmap_write_protect(kvm, rmapp, true);
+		write_protected |= __rmap_write_protect(kvm, rmapp, true, false);
 	}
 
 	return write_protected;
@@ -4565,7 +4582,7 @@
 
 		for (index = 0; index <= last_index; ++index, ++rmapp) {
 			if (*rmapp)
-				__rmap_write_protect(kvm, rmapp, false);
+				__rmap_write_protect(kvm, rmapp, false, false);
 
 			if (need_resched() || spin_needbreak(&kvm->mmu_lock))
 				cond_resched_lock(&kvm->mmu_lock);


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