linux-kernel - [PATCH v2 7/8] KVM: x86/mmu: Hoist ITLB multi-hit workaround check up a level

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Date:   Wed, 23 Sep 2020 11:37:34 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Junaid Shahid <junaids@...gle.com>
Subject: [PATCH v2 7/8] KVM: x86/mmu: Hoist ITLB multi-hit workaround check up a level

Move the "ITLB multi-hit workaround enabled" check into the callers of
disallowed_hugepage_adjust() to make it more obvious that the helper is
specific to the workaround, and to be consistent with the accounting,
i.e. account_huge_nx_page() is called if and only if the workaround is
enabled.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/mmu/mmu.c         | 4 ++--
 arch/x86/kvm/mmu/paging_tmpl.h | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0957795be384..fbee958927ce 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3302,7 +3302,6 @@ static void disallowed_hugepage_adjust(struct kvm_shadow_walk_iterator it,
 	u64 spte = *it.sptep;
 
 	if (it.level == level && level > PG_LEVEL_4K &&
-	    is_nx_huge_page_enabled() &&
 	    is_shadow_present_pte(spte) &&
 	    !is_large_pte(spte)) {
 		/*
@@ -3344,7 +3343,8 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 		 * We cannot overwrite existing page tables with an NX
 		 * large page, as the leaf could be executable.
 		 */
-		disallowed_hugepage_adjust(it, gfn, &pfn, &level);
+		if (nx_huge_page_workaround_enabled)
+			disallowed_hugepage_adjust(it, gfn, &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 26dde437abc0..84ea1094fbe2 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -694,7 +694,8 @@ 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, &level);
+		if (nx_huge_page_workaround_enabled)
+			disallowed_hugepage_adjust(it, gw->gfn, &pfn, &level);
 
 		base_gfn = gw->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
 		if (it.level == level)
-- 
2.28.0