linux-kernel - [PATCH v3 31/37] KVM: x86/mmu: Add separate override for MMU sync during fast CR3 switch

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Message-Id: <20200320212833.3507-32-sean.j.christopherson@intel.com>
Date:   Fri, 20 Mar 2020 14:28:27 -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, Ben Gardon <bgardon@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Liran Alon <liran.alon@...cle.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        John Haxby <john.haxby@...cle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: [PATCH v3 31/37] KVM: x86/mmu: Add separate override for MMU sync during fast CR3 switch

Add a separate "skip" override for MMU sync, a future change to avoid
TLB flushes on nested VMX transitions may need to sync the MMU even if
the TLB flush is unnecessary.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/kvm_host.h |  3 ++-
 arch/x86/kvm/mmu/mmu.c          | 13 +++++++------
 arch/x86/kvm/vmx/nested.c       |  2 +-
 arch/x86/kvm/x86.c              |  2 +-
 4 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 31aa93088bf9..6fca2e45886c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1517,7 +1517,8 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
 		       void *insn, int insn_len);
 void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva);
 void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid);
-void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush);
+void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush,
+		     bool skip_mmu_sync);
 
 void kvm_configure_mmu(bool enable_tdp, int tdp_page_level);
 
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b95933198f4c..06e94ca59a2d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4307,7 +4307,7 @@ static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3,
 
 static void __kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3,
 			      union kvm_mmu_page_role new_role,
-			      bool skip_tlb_flush)
+			      bool skip_tlb_flush, bool skip_mmu_sync)
 {
 	if (!fast_cr3_switch(vcpu, new_cr3, new_role)) {
 		kvm_mmu_free_roots(vcpu, vcpu->arch.mmu, KVM_MMU_ROOT_CURRENT);
@@ -4322,10 +4322,10 @@ static void __kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3,
 	 */
 	kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
 
-	if (!skip_tlb_flush) {
+	if (!skip_mmu_sync)
 		kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
+	if (!skip_tlb_flush)
 		kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
-	}
 
 	/*
 	 * The last MMIO access's GVA and GPA are cached in the VCPU. When
@@ -4338,10 +4338,11 @@ static void __kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3,
 	__clear_sp_write_flooding_count(page_header(vcpu->arch.mmu->root_hpa));
 }
 
-void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush)
+void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush,
+		     bool skip_mmu_sync)
 {
 	__kvm_mmu_new_cr3(vcpu, new_cr3, kvm_mmu_calc_root_page_role(vcpu),
-			  skip_tlb_flush);
+			  skip_tlb_flush, skip_mmu_sync);
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_new_cr3);
 
@@ -5034,7 +5035,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 		kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty,
 						   execonly, level);
 
-	__kvm_mmu_new_cr3(vcpu, new_eptp, new_role.base, false);
+	__kvm_mmu_new_cr3(vcpu, new_eptp, new_role.base, false, false);
 
 	if (new_role.as_u64 == context->mmu_role.as_u64)
 		return;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 06fc0b68ecf3..dd58563ee793 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1123,7 +1123,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
 	}
 
 	if (!nested_ept)
-		kvm_mmu_new_cr3(vcpu, cr3, false);
+		kvm_mmu_new_cr3(vcpu, cr3, false, false);
 
 	vcpu->arch.cr3 = cr3;
 	kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 26c24af87cca..0d1572a0791c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1045,7 +1045,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
 		 !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
 		return 1;
 
-	kvm_mmu_new_cr3(vcpu, cr3, skip_tlb_flush);
+	kvm_mmu_new_cr3(vcpu, cr3, skip_tlb_flush, skip_tlb_flush);
 	vcpu->arch.cr3 = cr3;
 	kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
 
-- 
2.24.1