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[RFC,2/2] kvm, x86: use ro page and don't copy shared page

Message ID 4C0F4883.3010100@cn.fujitsu.com (mailing list archive)
State New, archived
Headers show

Commit Message

Lai Jiangshan June 9, 2010, 7:53 a.m. UTC
None
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Patch

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 9b9b1c3..1e0826d 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1902,7 +1902,7 @@  static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 		    unsigned pte_access, int user_fault,
 		    int write_fault, int dirty, int level,
 		    gfn_t gfn, pfn_t pfn, bool speculative,
-		    bool can_unsync, bool reset_host_protection)
+		    bool can_unsync, bool host_writable)
 {
 	u64 spte;
 	int ret = 0;
@@ -1929,8 +1929,10 @@  static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 		spte |= kvm_x86_ops->get_mt_mask(vcpu, gfn,
 			kvm_is_mmio_pfn(pfn));
 
-	if (reset_host_protection)
+	if (host_writable)
 		spte |= SPTE_HOST_WRITEABLE;
+	else
+		pte_access &= ~ACC_WRITE_MASK;
 
 	spte |= (u64)pfn << PAGE_SHIFT;
 
@@ -1983,7 +1985,7 @@  static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 			 int user_fault, int write_fault, int dirty,
 			 int *ptwrite, int level, gfn_t gfn,
 			 pfn_t pfn, bool speculative,
-			 bool reset_host_protection)
+			 bool host_writable)
 {
 	int was_rmapped = 0;
 	int was_writable = is_writable_pte(*sptep);
@@ -2018,7 +2020,7 @@  static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 
 	if (set_spte(vcpu, sptep, pte_access, user_fault, write_fault,
 		      dirty, level, gfn, pfn, speculative, true,
-		      reset_host_protection)) {
+		      host_writable)) {
 		if (write_fault)
 			*ptwrite = 1;
 		kvm_x86_ops->tlb_flush(vcpu);
@@ -2066,7 +2068,7 @@  static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
 		if (iterator.level == level) {
 			mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, ACC_ALL,
 				     0, write, 1, &pt_write,
-				     level, gfn, pfn, false, true);
+				     level, gfn, pfn, false, write);
 			++vcpu->stat.pf_fixed;
 			break;
 		}
@@ -2135,7 +2137,7 @@  static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
 
 	mmu_seq = vcpu->kvm->mmu_notifier_seq;
 	smp_rmb();
-	pfn = kvm_get_pfn_for_gfn(vcpu->kvm, gfn, 1);
+	pfn = kvm_get_pfn_for_gfn(vcpu->kvm, gfn, write);
 
 	/* mmio */
 	if (is_error_pfn(pfn))
@@ -2357,7 +2359,12 @@  static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
 
 	mmu_seq = vcpu->kvm->mmu_notifier_seq;
 	smp_rmb();
-	pfn = kvm_get_pfn_for_gfn(vcpu->kvm, gfn, 1);
+	pfn = kvm_get_pfn_for_gfn(vcpu->kvm, gfn, error_code & PFERR_WRITE_MASK);
+	if (!(error_code & PFERR_WRITE_MASK) && kvm_is_mmio_pfn(pfn)) {
+		kvm_release_pfn_clean(pfn);
+		/* I don't know why we have to ensure mmio pfns are always writable. */
+		pfn = kvm_get_pfn_for_gfn(vcpu->kvm, gfn, 1);
+	}
 	if (is_error_pfn(pfn))
 		return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
 	spin_lock(&vcpu->kvm->mmu_lock);
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index fddb726..e0cb33a 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -283,7 +283,7 @@  static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
 		return;
 	kvm_get_pfn(pfn);
 	/*
-	 * we call mmu_set_spte() with reset_host_protection = true beacuse that
+	 * we call mmu_set_spte() with host_writable = true beacuse that
 	 * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
 	 */
 	mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
@@ -321,7 +321,7 @@  static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 				     user_fault, write_fault,
 				     gw->ptes[gw->level-1] & PT_DIRTY_MASK,
 				     ptwrite, level,
-				     gw->gfn, pfn, false, true);
+				     gw->gfn, pfn, false, write_fault);
 			break;
 		}
 
@@ -430,7 +430,7 @@  static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
 
 	mmu_seq = vcpu->kvm->mmu_notifier_seq;
 	smp_rmb();
-	pfn = kvm_get_pfn_for_gfn(vcpu->kvm, walker.gfn, 1);
+	pfn = kvm_get_pfn_for_gfn(vcpu->kvm, walker.gfn, write_fault);
 
 	/* mmio */
 	if (is_error_pfn(pfn))
@@ -579,7 +579,7 @@  static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
 static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 {
 	int i, offset, nr_present;
-	bool reset_host_protection;
+	bool host_writable;
 	gpa_t first_pte_gpa;
 
 	offset = nr_present = 0;
@@ -623,15 +623,14 @@  static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 		nr_present++;
 		pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
 		if (!(sp->spt[i] & SPTE_HOST_WRITEABLE)) {
-			pte_access &= ~ACC_WRITE_MASK;
-			reset_host_protection = 0;
+			host_writable = false;
 		} else {
-			reset_host_protection = 1;
+			host_writable = true;
 		}
 		set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
 			 is_dirty_gpte(gpte), PT_PAGE_TABLE_LEVEL, gfn,
 			 spte_to_pfn(sp->spt[i]), true, false,
-			 reset_host_protection);
+			 host_writable);
 	}
 
 	return !nr_present;