KVM: x86/mmu: Move guest PT write-protection to account_shadowed()

Move the code that write-protects newly-shadowed guest page tables into
account_shadowed(). This avoids a extra gfn-to-memslot lookup and is a
more logical place for this code to live. But most importantly, this
reduces kvm_mmu_alloc_shadow_page()'s reliance on having a struct
kvm_vcpu pointer, which will be necessary when creating new shadow pages
during VM ioctls for eager page splitting.

Note, it is safe to drop the role.level == PG_LEVEL_4K check since
account_shadowed() returns early if role.level > PG_LEVEL_4K.

No functional change intended.

Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-10-dmatlack@google.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 bd45364..2602c36 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -766,6 +766,9 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
                                                    KVM_PAGE_TRACK_WRITE);
 
        kvm_mmu_gfn_disallow_lpage(slot, gfn);
+
+       if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K))
+               kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
 }
 
 void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp)
@@ -2072,11 +2075,8 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
        sp->gfn = gfn;
        sp->role = role;
        hlist_add_head(&sp->hash_link, sp_list);
-       if (sp_has_gptes(sp)) {
+       if (sp_has_gptes(sp))
                account_shadowed(vcpu->kvm, sp);
-               if (role.level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
-                       kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
-       }
 
        return sp;
 }