[PATCH 4.9 20/31] KVM: x86: make FNAME(fetch) and __direct_map more similar

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Paolo Bonzini <pbonzini@redhat.com>

commit 3fcf2d1bdeb6a513523cb2c77012a6b047aa859c upstream.

These two functions are basically doing the same thing through
kvm_mmu_get_page, link_shadow_page and mmu_set_spte; yet, for historical
reasons, their code looks very different.  This patch tries to take the
best of each and make them very similar, so that it is easy to understand
changes that apply to both of them.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kvm/mmu.c         |   53 +++++++++++++++++++++------------------------
 arch/x86/kvm/paging_tmpl.h |   30 +++++++++++--------------
 2 files changed, 39 insertions(+), 44 deletions(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2757,40 +2757,39 @@ static void direct_pte_prefetch(struct k
 	__direct_pte_prefetch(vcpu, sp, sptep);
 }
 
-static int __direct_map(struct kvm_vcpu *vcpu, int write, int map_writable,
-			int level, gfn_t gfn, kvm_pfn_t pfn, bool prefault)
+static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, int write,
+			int map_writable, int level, kvm_pfn_t pfn,
+			bool prefault)
 {
-	struct kvm_shadow_walk_iterator iterator;
+	struct kvm_shadow_walk_iterator it;
 	struct kvm_mmu_page *sp;
-	int emulate = 0;
-	gfn_t pseudo_gfn;
+	int ret;
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	gfn_t base_gfn = gfn;
 
 	if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
-		return 0;
+		return RET_PF_RETRY;
 
-	for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
-		if (iterator.level == level) {
-			emulate = mmu_set_spte(vcpu, iterator.sptep, ACC_ALL,
-					       write, level, gfn, pfn, prefault,
-					       map_writable);
-			direct_pte_prefetch(vcpu, iterator.sptep);
-			++vcpu->stat.pf_fixed;
+	for_each_shadow_entry(vcpu, gpa, it) {
+		base_gfn = gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
+		if (it.level == level)
 			break;
-		}
 
-		drop_large_spte(vcpu, iterator.sptep);
-		if (!is_shadow_present_pte(*iterator.sptep)) {
-			u64 base_addr = iterator.addr;
-
-			base_addr &= PT64_LVL_ADDR_MASK(iterator.level);
-			pseudo_gfn = base_addr >> PAGE_SHIFT;
-			sp = kvm_mmu_get_page(vcpu, pseudo_gfn, iterator.addr,
-					      iterator.level - 1, 1, ACC_ALL);
+		drop_large_spte(vcpu, it.sptep);
+		if (!is_shadow_present_pte(*it.sptep)) {
+			sp = kvm_mmu_get_page(vcpu, base_gfn, it.addr,
+					      it.level - 1, true, ACC_ALL);
 
-			link_shadow_page(vcpu, iterator.sptep, sp);
+			link_shadow_page(vcpu, it.sptep, sp);
 		}
 	}
-	return emulate;
+
+	ret = mmu_set_spte(vcpu, it.sptep, ACC_ALL,
+			   write, level, base_gfn, pfn, prefault,
+			   map_writable);
+	direct_pte_prefetch(vcpu, it.sptep);
+	++vcpu->stat.pf_fixed;
+	return ret;
 }
 
 static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk)
@@ -3062,8 +3061,7 @@ static int nonpaging_map(struct kvm_vcpu
 	make_mmu_pages_available(vcpu);
 	if (likely(!force_pt_level))
 		transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
-	r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault);
-
+	r = __direct_map(vcpu, v, write, map_writable, level, pfn, prefault);
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
@@ -3598,8 +3596,7 @@ static int tdp_page_fault(struct kvm_vcp
 	make_mmu_pages_available(vcpu);
 	if (likely(!force_pt_level))
 		transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
-	r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault);
-
+	r = __direct_map(vcpu, gpa, write, map_writable, level, pfn, prefault);
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -579,6 +579,7 @@ static int FNAME(fetch)(struct kvm_vcpu
 	struct kvm_shadow_walk_iterator it;
 	unsigned direct_access, access = gw->pt_access;
 	int top_level, ret;
+	gfn_t base_gfn;
 
 	direct_access = gw->pte_access;
 
@@ -623,31 +624,29 @@ static int FNAME(fetch)(struct kvm_vcpu
 			link_shadow_page(vcpu, it.sptep, sp);
 	}
 
-	for (;
-	     shadow_walk_okay(&it) && it.level > hlevel;
-	     shadow_walk_next(&it)) {
-		gfn_t direct_gfn;
+	base_gfn = gw->gfn;
 
+	for (; shadow_walk_okay(&it); shadow_walk_next(&it)) {
 		clear_sp_write_flooding_count(it.sptep);
+		base_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
+		if (it.level == hlevel)
+			break;
+
 		validate_direct_spte(vcpu, it.sptep, direct_access);
 
 		drop_large_spte(vcpu, it.sptep);
 
-		if (is_shadow_present_pte(*it.sptep))
-			continue;
-
-		direct_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
-
-		sp = kvm_mmu_get_page(vcpu, direct_gfn, addr, it.level-1,
-				      true, direct_access);
-		link_shadow_page(vcpu, it.sptep, sp);
+		if (!is_shadow_present_pte(*it.sptep)) {
+			sp = kvm_mmu_get_page(vcpu, base_gfn, addr,
+					      it.level - 1, true, direct_access);
+			link_shadow_page(vcpu, it.sptep, sp);
+		}
 	}
 
-	clear_sp_write_flooding_count(it.sptep);
 	ret = mmu_set_spte(vcpu, it.sptep, gw->pte_access, write_fault,
-			   it.level, gw->gfn, pfn, prefault, map_writable);
+			   it.level, base_gfn, pfn, prefault, map_writable);
 	FNAME(pte_prefetch)(vcpu, gw, it.sptep);
-
+	++vcpu->stat.pf_fixed;
 	return ret;
 
 out_gpte_changed:
@@ -810,7 +809,6 @@ static int FNAME(page_fault)(struct kvm_
 		transparent_hugepage_adjust(vcpu, &walker.gfn, &pfn, &level);
 	r = FNAME(fetch)(vcpu, addr, &walker, write_fault,
 			 level, pfn, map_writable, prefault);
-	++vcpu->stat.pf_fixed;
 	kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);
 
 out_unlock: