linux-kernel - [PATCH 09/22] kvm: mmu: Remove disallowed_hugepage_adjust shadow_walk

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Date:   Fri, 25 Sep 2020 14:22:49 -0700
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Cannon Matthews <cannonmatthews@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Peter Shier <pshier@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH 09/22] kvm: 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@...gle.com>
---
 arch/x86/kvm/mmu/mmu.c         | 17 +++++++++--------
 arch/x86/kvm/mmu/paging_tmpl.h |  3 ++-
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 6344e7863a0f5..f6e6fc9959c04 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3295,13 +3295,12 @@ 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 *goal_levelp)
 {
-	int level = *levelp;
-	u64 spte = *it.sptep;
+	int goal_level = *goal_levelp;
 
-	if (it.level == level && level > PG_LEVEL_4K &&
+	if (cur_level == goal_level && goal_level > PG_LEVEL_4K &&
 	    is_nx_huge_page_enabled() &&
 	    is_shadow_present_pte(spte) &&
 	    !is_large_pte(spte)) {
@@ -3312,9 +3311,10 @@ 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(goal_level) -
+				KVM_PAGES_PER_HPAGE(goal_level - 1);
 		*pfnp |= gfn & page_mask;
-		(*levelp)--;
+		(*goal_levelp)--;
 	}
 }
 
@@ -3339,7 +3339,8 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, int write,
 		 * We cannot overwrite existing page tables with an NX
 		 * large page, as the leaf could be executable.
 		 */
-		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)
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 4dd6b1e5b8cf7..6a8666cb0d24b 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -690,7 +690,8 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gpa_t addr,
 		 * We cannot overwrite existing page tables with an NX
 		 * large page, as the leaf could be executable.
 		 */
-		disallowed_hugepage_adjust(it, gw->gfn, &pfn, &hlevel);
+		disallowed_hugepage_adjust(*it.sptep, gw->gfn, it.level,
+					   &pfn, &hlevel);
 
 		base_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
 		if (it.level == hlevel)
-- 
2.28.0.709.gb0816b6eb0-goog