KVM: x86/mmu: Move fast_cr3_switch() side effects to __kvm_mmu_new_cr3()

Handle the side effects of a fast CR3 (PGD) switch up a level in
__kvm_mmu_new_cr3(), which is the only caller of fast_cr3_switch().

This consolidates handling all side effects in __kvm_mmu_new_cr3()
(where freeing the current root when KVM can't do a fast switch is
already handled), and ameliorates the pain of adding a second boolean in
a future patch to provide a separate "skip" override for the MMU sync.

Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200320212833.3507-31-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 575bd5d..6a93920 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4284,8 +4284,7 @@ static bool cached_root_available(struct kvm_vcpu *vcpu, gpa_t new_cr3,
 }
 
 static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3,
-                           union kvm_mmu_page_role new_role,
-                           bool skip_tlb_flush)
+                           union kvm_mmu_page_role new_role)
 {
        struct kvm_mmu *mmu = vcpu->arch.mmu;
 
@@ -4295,39 +4294,9 @@ static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3,
         * later if necessary.
         */
        if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
-           mmu->root_level >= PT64_ROOT_4LEVEL) {
-               if (mmu_check_root(vcpu, new_cr3 >> PAGE_SHIFT))
-                       return false;
-
-               if (cached_root_available(vcpu, new_cr3, new_role)) {
-                       /*
-                        * It is possible that the cached previous root page is
-                        * obsolete because of a change in the MMU generation
-                        * number. However, changing the generation number is
-                        * accompanied by KVM_REQ_MMU_RELOAD, which will free
-                        * the root set here and allocate a new one.
-                        */
-                       kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
-                       if (!skip_tlb_flush) {
-                               kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
-                               kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
-                       }
-
-                       /*
-                        * The last MMIO access's GVA and GPA are cached in the
-                        * VCPU. When switching to a new CR3, that GVA->GPA
-                        * mapping may no longer be valid. So clear any cached
-                        * MMIO info even when we don't need to sync the shadow
-                        * page tables.
-                        */
-                       vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY);
-
-                       __clear_sp_write_flooding_count(
-                               page_header(mmu->root_hpa));
-
-                       return true;
-               }
-       }
+           mmu->root_level >= PT64_ROOT_4LEVEL)
+               return !mmu_check_root(vcpu, new_cr3 >> PAGE_SHIFT) &&
+                      cached_root_available(vcpu, new_cr3, new_role);
 
        return false;
 }
@@ -4336,9 +4305,33 @@ 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)
 {
-       if (!fast_cr3_switch(vcpu, new_cr3, new_role, skip_tlb_flush))
-               kvm_mmu_free_roots(vcpu, vcpu->arch.mmu,
-                                  KVM_MMU_ROOT_CURRENT);
+       if (!fast_cr3_switch(vcpu, new_cr3, new_role)) {
+               kvm_mmu_free_roots(vcpu, vcpu->arch.mmu, KVM_MMU_ROOT_CURRENT);
+               return;
+       }
+
+       /*
+        * It's possible that the cached previous root page is obsolete because
+        * of a change in the MMU generation number. However, changing the
+        * generation number is accompanied by KVM_REQ_MMU_RELOAD, which will
+        * free the root set here and allocate a new one.
+        */
+       kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
+
+       if (!skip_tlb_flush) {
+               kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
+               kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
+       }
+
+       /*
+        * The last MMIO access's GVA and GPA are cached in the VCPU. When
+        * switching to a new CR3, that GVA->GPA mapping may no longer be
+        * valid. So clear any cached MMIO info even when we don't need to sync
+        * the shadow page tables.
+        */
+       vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY);
+
+       __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)