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Commit b34cb590 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Gleb Natapov
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KVM: Make kvm_mmu_change_mmu_pages() take mmu_lock by itself 



No reason to make callers take mmu_lock since we do not need to protect
kvm_mmu_change_mmu_pages() and kvm_mmu_slot_remove_write_access()
together by mmu_lock in kvm_arch_commit_memory_region(): the former
calls kvm_mmu_commit_zap_page() and flushes TLBs by itself.

Note: we do not need to protect kvm->arch.n_requested_mmu_pages by
mmu_lock as can be seen from the fact that it is read locklessly.

Reviewed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent e12091ce

arch/x86/kvm/mmu.c

+4 −0
Original line number Diff line number Diff line
@@ -2143,6 +2143,8 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int goal_nr_mmu_pages) 
	 * change the value

	 */



	spin_lock(&kvm->mmu_lock);



	if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) {

		while (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages &&

			!list_empty(&kvm->arch.active_mmu_pages)) {
@@ -2157,6 +2159,8 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int goal_nr_mmu_pages) 
	}



	kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages;



	spin_unlock(&kvm->mmu_lock);

}



int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)

arch/x86/kvm/x86.c

+4 −5
Original line number Diff line number Diff line
@@ -3270,12 +3270,10 @@ static int kvm_vm_ioctl_set_nr_mmu_pages(struct kvm *kvm, 
		return -EINVAL;



	mutex_lock(&kvm->slots_lock);

	spin_lock(&kvm->mmu_lock);



	kvm_mmu_change_mmu_pages(kvm, kvm_nr_mmu_pages);

	kvm->arch.n_requested_mmu_pages = kvm_nr_mmu_pages;



	spin_unlock(&kvm->mmu_lock);

	mutex_unlock(&kvm->slots_lock);

	return 0;

}
@@ -6894,7 +6892,6 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, 
	if (!kvm->arch.n_requested_mmu_pages)

		nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);



	spin_lock(&kvm->mmu_lock);

	if (nr_mmu_pages)

		kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);

	/*
@@ -6902,9 +6899,11 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, 
	 * Existing largepage mappings are destroyed here and new ones will

	 * not be created until the end of the logging.

	 */

	if (npages && (mem->flags & KVM_MEM_LOG_DIRTY_PAGES))

	if (npages && (mem->flags & KVM_MEM_LOG_DIRTY_PAGES)) {

		spin_lock(&kvm->mmu_lock);

		kvm_mmu_slot_remove_write_access(kvm, mem->slot);

		spin_unlock(&kvm->mmu_lock);

	}

	/*

	 * If memory slot is created, or moved, we need to clear all

	 * mmio sptes.