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Commit 889e5cbc authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

KVM: MMU: split kvm_mmu_pte_write function 



kvm_mmu_pte_write is too long, we split it for better readable

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent f8734352

arch/x86/kvm/mmu.c

+119 −75
Original line number Diff line number Diff line
@@ -3530,48 +3530,28 @@ static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu) 
	return !!(spte && (*spte & shadow_accessed_mask));

}



void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,

		       const u8 *new, int bytes)

static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa,

				    const u8 *new, int *bytes)

{

	gfn_t gfn = gpa >> PAGE_SHIFT;

	union kvm_mmu_page_role mask = { .word = 0 };

	struct kvm_mmu_page *sp;

	struct hlist_node *node;

	LIST_HEAD(invalid_list);

	u64 entry, gentry, *spte;

	unsigned pte_size, page_offset, misaligned, quadrant, offset;

	int level, npte, r, flooded = 0;

	bool remote_flush, local_flush, zap_page;



	/*

	 * If we don't have indirect shadow pages, it means no page is

	 * write-protected, so we can exit simply.

	 */

	if (!ACCESS_ONCE(vcpu->kvm->arch.indirect_shadow_pages))

		return;



	zap_page = remote_flush = local_flush = false;

	offset = offset_in_page(gpa);



	pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes);

	u64 gentry;

	int r;



	/*

	 * Assume that the pte write on a page table of the same type

	 * as the current vcpu paging mode since we update the sptes only

	 * when they have the same mode.

	 */

	if (is_pae(vcpu) && bytes == 4) {

	if (is_pae(vcpu) && *bytes == 4) {

		/* Handle a 32-bit guest writing two halves of a 64-bit gpte */

		gpa &= ~(gpa_t)7;

		bytes = 8;



		r = kvm_read_guest(vcpu->kvm, gpa, &gentry, min(bytes, 8));

		*gpa &= ~(gpa_t)7;

		*bytes = 8;

		r = kvm_read_guest(vcpu->kvm, *gpa, &gentry, min(*bytes, 8));

		if (r)

			gentry = 0;

		new = (const u8 *)&gentry;

	}



	switch (bytes) {

	switch (*bytes) {

	case 4:

		gentry = *(const u32 *)new;

		break;
@@ -3583,52 +3563,60 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, 
		break;

	}



	return gentry;

}



/*

	 * No need to care whether allocation memory is successful

	 * or not since pte prefetch is skiped if it does not have

	 * enough objects in the cache.

 * If we're seeing too many writes to a page, it may no longer be a page table,

 * or we may be forking, in which case it is better to unmap the page.

 */

	mmu_topup_memory_caches(vcpu);

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

	++vcpu->kvm->stat.mmu_pte_write;

	trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);

static bool detect_write_flooding(struct kvm_vcpu *vcpu, gfn_t gfn)

{

	bool flooded = false;



	if (gfn == vcpu->arch.last_pt_write_gfn

	    && !last_updated_pte_accessed(vcpu)) {

		++vcpu->arch.last_pt_write_count;

		if (vcpu->arch.last_pt_write_count >= 3)

			flooded = 1;

			flooded = true;

	} else {

		vcpu->arch.last_pt_write_gfn = gfn;

		vcpu->arch.last_pt_write_count = 1;

		vcpu->arch.last_pte_updated = NULL;

	}



	mask.cr0_wp = mask.cr4_pae = mask.nxe = 1;

	for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn, node) {

		pte_size = sp->role.cr4_pae ? 8 : 4;

		misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);

		misaligned |= bytes < 4;

		if (misaligned || flooded) {

	return flooded;

}



/*

			 * Misaligned accesses are too much trouble to fix

			 * up; also, they usually indicate a page is not used

			 * as a page table.

			 *

			 * If we're seeing too many writes to a page,

			 * it may no longer be a page table, or we may be

			 * forking, in which case it is better to unmap the

			 * page.

 * Misaligned accesses are too much trouble to fix up; also, they usually

 * indicate a page is not used as a page table.

 */

static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa,

				    int bytes)

{

	unsigned offset, pte_size, misaligned;



	pgprintk("misaligned: gpa %llx bytes %d role %x\n",

		 gpa, bytes, sp->role.word);

			zap_page |= !!kvm_mmu_prepare_zap_page(vcpu->kvm, sp,

						     &invalid_list);

			++vcpu->kvm->stat.mmu_flooded;

			continue;



	offset = offset_in_page(gpa);

	pte_size = sp->role.cr4_pae ? 8 : 4;

	misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);

	misaligned |= bytes < 4;



	return misaligned;

}

		page_offset = offset;



static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte)

{

	unsigned page_offset, quadrant;

	u64 *spte;

	int level;



	page_offset = offset_in_page(gpa);

	level = sp->role.level;

		npte = 1;

	*nspte = 1;

	if (!sp->role.cr4_pae) {

		page_offset <<= 1;	/* 32->64 */

		/*
@@ -3639,15 +3627,71 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, 
		if (level == PT32_ROOT_LEVEL) {

			page_offset &= ~7; /* kill rounding error */

			page_offset <<= 1;

				npte = 2;

			*nspte = 2;

		}

		quadrant = page_offset >> PAGE_SHIFT;

		page_offset &= ~PAGE_MASK;

		if (quadrant != sp->role.quadrant)

			return NULL;

	}



	spte = &sp->spt[page_offset / sizeof(*spte)];

	return spte;

}



void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,

		       const u8 *new, int bytes)

{

	gfn_t gfn = gpa >> PAGE_SHIFT;

	union kvm_mmu_page_role mask = { .word = 0 };

	struct kvm_mmu_page *sp;

	struct hlist_node *node;

	LIST_HEAD(invalid_list);

	u64 entry, gentry, *spte;

	int npte;

	bool remote_flush, local_flush, zap_page, flooded, misaligned;



	/*

	 * If we don't have indirect shadow pages, it means no page is

	 * write-protected, so we can exit simply.

	 */

	if (!ACCESS_ONCE(vcpu->kvm->arch.indirect_shadow_pages))

		return;



	zap_page = remote_flush = local_flush = false;



	pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes);



	gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, new, &bytes);



	/*

	 * No need to care whether allocation memory is successful

	 * or not since pte prefetch is skiped if it does not have

	 * enough objects in the cache.

	 */

	mmu_topup_memory_caches(vcpu);



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

	++vcpu->kvm->stat.mmu_pte_write;

	trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);



	flooded = detect_write_flooding(vcpu, gfn);

	mask.cr0_wp = mask.cr4_pae = mask.nxe = 1;

	for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn, node) {

		misaligned = detect_write_misaligned(sp, gpa, bytes);



		if (misaligned || flooded) {

			zap_page |= !!kvm_mmu_prepare_zap_page(vcpu->kvm, sp,

						     &invalid_list);

			++vcpu->kvm->stat.mmu_flooded;

			continue;

		}



		spte = get_written_sptes(sp, gpa, &npte);

		if (!spte)

			continue;



		local_flush = true;

		spte = &sp->spt[page_offset / sizeof(*spte)];

		while (npte--) {

			entry = *spte;

			mmu_page_zap_pte(vcpu->kvm, sp, spte);