Commit 651dd37a authored by Joerg Roedel's avatar Joerg Roedel Committed by Avi Kivity
Browse files

KVM: MMU: Refactor mmu_alloc_roots function 



This patch factors out the direct-mapping paths of the
mmu_alloc_roots function into a seperate function. This
makes it a lot easier to avoid all the unnecessary checks
done in the shadow path which may break when running direct.
In fact, this patch already fixes a problem when running PAE
guests on a PAE shadow page table.

Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent d41d1895

arch/x86/kvm/mmu.c

+60 −22
Original line number Diff line number Diff line
@@ -2357,42 +2357,77 @@ static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn) 
	return ret;

}



static int mmu_alloc_roots(struct kvm_vcpu *vcpu)

static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)

{

	struct kvm_mmu_page *sp;

	int i;



	if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {

		spin_lock(&vcpu->kvm->mmu_lock);

		kvm_mmu_free_some_pages(vcpu);

		sp = kvm_mmu_get_page(vcpu, 0, 0, PT64_ROOT_LEVEL,

				      1, ACC_ALL, NULL);

		++sp->root_count;

		spin_unlock(&vcpu->kvm->mmu_lock);

		vcpu->arch.mmu.root_hpa = __pa(sp->spt);

	} else if (vcpu->arch.mmu.shadow_root_level == PT32E_ROOT_LEVEL) {

		for (i = 0; i < 4; ++i) {

			hpa_t root = vcpu->arch.mmu.pae_root[i];



			ASSERT(!VALID_PAGE(root));

			spin_lock(&vcpu->kvm->mmu_lock);

			kvm_mmu_free_some_pages(vcpu);

			sp = kvm_mmu_get_page(vcpu, i << 30, i << 30,

					      PT32_ROOT_LEVEL, 1, ACC_ALL,

					      NULL);

			root = __pa(sp->spt);

			++sp->root_count;

			spin_unlock(&vcpu->kvm->mmu_lock);

			vcpu->arch.mmu.pae_root[i] = root | PT_PRESENT_MASK;

			vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.pae_root);

		}

	} else

		BUG();



	return 0;

}



static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)

{

	int i;

	gfn_t root_gfn;

	struct kvm_mmu_page *sp;

	int direct = 0;

	u64 pdptr;



	root_gfn = vcpu->arch.mmu.get_cr3(vcpu) >> PAGE_SHIFT;



	if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {

	if (mmu_check_root(vcpu, root_gfn))

		return 1;



	/*

	 * Do we shadow a long mode page table? If so we need to

	 * write-protect the guests page table root.

	 */

	if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) {

		hpa_t root = vcpu->arch.mmu.root_hpa;



		ASSERT(!VALID_PAGE(root));

		if (mmu_check_root(vcpu, root_gfn))

			return 1;

		if (vcpu->arch.mmu.direct_map) {

			direct = 1;

			root_gfn = 0;

		}



		spin_lock(&vcpu->kvm->mmu_lock);

		kvm_mmu_free_some_pages(vcpu);

		sp = kvm_mmu_get_page(vcpu, root_gfn, 0,

				      PT64_ROOT_LEVEL, direct,

				      ACC_ALL, NULL);

		sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL,

				      0, ACC_ALL, NULL);

		root = __pa(sp->spt);

		++sp->root_count;

		spin_unlock(&vcpu->kvm->mmu_lock);

		vcpu->arch.mmu.root_hpa = root;

		return 0;

	}

	direct = !is_paging(vcpu);



	if (mmu_check_root(vcpu, root_gfn))

		return 1;



	/*

	 * We shadow a 32 bit page table. This may be a legacy 2-level

	 * or a PAE 3-level page table.

	 */

	for (i = 0; i < 4; ++i) {

		hpa_t root = vcpu->arch.mmu.pae_root[i];
@@ -2406,16 +2441,11 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu) 
			root_gfn = pdptr >> PAGE_SHIFT;

			if (mmu_check_root(vcpu, root_gfn))

				return 1;

		} else if (vcpu->arch.mmu.root_level == 0)

			root_gfn = 0;

		if (vcpu->arch.mmu.direct_map) {

			direct = 1;

			root_gfn = i << 30;

		}

		spin_lock(&vcpu->kvm->mmu_lock);

		kvm_mmu_free_some_pages(vcpu);

		sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,

				      PT32_ROOT_LEVEL, direct,

				      PT32_ROOT_LEVEL, 0,

				      ACC_ALL, NULL);

		root = __pa(sp->spt);

		++sp->root_count;
@@ -2427,6 +2457,14 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu) 
	return 0;

}



static int mmu_alloc_roots(struct kvm_vcpu *vcpu)

{

	if (vcpu->arch.mmu.direct_map)

		return mmu_alloc_direct_roots(vcpu);

	else

		return mmu_alloc_shadow_roots(vcpu);

}



static void mmu_sync_roots(struct kvm_vcpu *vcpu)

{

	int i;

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