linux-kernel - [PATCH 05/16] KVM: x86/mmu: Refactor handling of cache consistency with TDP

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Message-Id: <20191206235729.29263-6-sean.j.christopherson@intel.com>
Date:   Fri,  6 Dec 2019 15:57:18 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...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
Subject: [PATCH 05/16] KVM: x86/mmu: Refactor handling of cache consistency with TDP

Pre-calculate the max level for a TDP page with respect to MTRR cache
consistency in preparation of replacing force_pt_level with max_level,
and eventually combining the bulk of nonpaging_page_fault() and
tdp_page_fault() into a common helper.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/mmu/mmu.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ef1b7663f6ea..e4a96236aa14 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4267,16 +4267,6 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
 }
 EXPORT_SYMBOL_GPL(kvm_handle_page_fault);
 
-static bool
-check_hugepage_cache_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, int level)
-{
-	int page_num = KVM_PAGES_PER_HPAGE(level);
-
-	gfn &= ~(page_num - 1);
-
-	return kvm_mtrr_check_gfn_range_consistency(vcpu, gfn, page_num);
-}
-
 static int tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 			  bool prefault)
 {
@@ -4290,6 +4280,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 	bool map_writable;
 	bool lpage_disallowed = (error_code & PFERR_FETCH_MASK) &&
 				is_nx_huge_page_enabled();
+	int max_level;
 
 	MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa));
 
@@ -4300,14 +4291,21 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 	if (r)
 		return r;
 
-	force_pt_level =
-		lpage_disallowed ||
-		!check_hugepage_cache_consistency(vcpu, gfn, PT_DIRECTORY_LEVEL);
+	for (max_level = PT_MAX_HUGEPAGE_LEVEL;
+	     max_level > PT_PAGE_TABLE_LEVEL;
+	     max_level--) {
+		int page_num = KVM_PAGES_PER_HPAGE(max_level);
+		gfn_t base = gfn & ~(page_num - 1);
+
+		if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num))
+			break;
+	}
+
+	force_pt_level = lpage_disallowed || max_level == PT_PAGE_TABLE_LEVEL;
 	level = mapping_level(vcpu, gfn, &force_pt_level);
 	if (likely(!force_pt_level)) {
-		if (level > PT_DIRECTORY_LEVEL &&
-		    !check_hugepage_cache_consistency(vcpu, gfn, level))
-			level = PT_DIRECTORY_LEVEL;
+		if (level > max_level)
+			level = max_level;
 		gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
 	}
 
-- 
2.24.0