kvm: x86/mmu: Remove disallowed_hugepage_adjust shadow_walk_iterator arg

In order to avoid creating executable hugepages in the TDP MMU PF
handler, remove the dependency between disallowed_hugepage_adjust and
the shadow_walk_iterator. This will open the function up to being used
by the TDP MMU PF handler in a future patch.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-10-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Author: Ben Gardon

arch/x86/kvm/mmu/mmu.c

@@ -2818,13 +2818,12 @@ static int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn,
 	return level;
 }
 
-static void disallowed_hugepage_adjust(struct kvm_shadow_walk_iterator it,
-				       gfn_t gfn, kvm_pfn_t *pfnp, int *levelp)
+static void disallowed_hugepage_adjust(u64 spte, gfn_t gfn, int cur_level,
+				       kvm_pfn_t *pfnp, int *levelp)
 {
 	int level = *levelp;
-	u64 spte = *it.sptep;
 
-	if (it.level == level && level > PG_LEVEL_4K &&
+	if (cur_level == level && level > PG_LEVEL_4K &&
 	    is_shadow_present_pte(spte) &&
 	    !is_large_pte(spte)) {
 		/*
@@ -2834,7 +2833,8 @@ static void disallowed_hugepage_adjust(struct kvm_shadow_walk_iterator it,
 		 * patching back for them into pfn the next 9 bits of
 		 * the address.
 		 */
-		u64 page_mask = KVM_PAGES_PER_HPAGE(level) - KVM_PAGES_PER_HPAGE(level - 1);
+		u64 page_mask = KVM_PAGES_PER_HPAGE(level) -
+				KVM_PAGES_PER_HPAGE(level - 1);
 		*pfnp |= gfn & page_mask;
 		(*levelp)--;
 	}
@@ -2867,7 +2867,8 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 		 * large page, as the leaf could be executable.
 		 */
 		if (nx_huge_page_workaround_enabled)
-			disallowed_hugepage_adjust(it, gfn, &pfn, &level);
+			disallowed_hugepage_adjust(*it.sptep, gfn, it.level,
+						   &pfn, &level);
 
 		base_gfn = gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
 		if (it.level == level)

arch/x86/kvm/mmu/paging_tmpl.h

@@ -695,7 +695,8 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gpa_t addr,
 		 * large page, as the leaf could be executable.
 		 */
 		if (nx_huge_page_workaround_enabled)
-			disallowed_hugepage_adjust(it, gw->gfn, &pfn, &level);
+			disallowed_hugepage_adjust(*it.sptep, gw->gfn, it.level,
+						   &pfn, &level);
 
 		base_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
 		if (it.level == level)