Commit be911771 authored by David Matlack's avatar David Matlack Committed by Paolo Bonzini
Browse files

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: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-10-dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 87654643

arch/x86/kvm/mmu/mmu.c

+4 −4
Original line number Diff line number Diff line
@@ -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;

}