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Commit 97a0a01e authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: MMU: Fold fix_write_pf() into set_pte_common() 



This prevents some work from being performed twice, and, more importantly,
reduces the number of places where we modify shadow ptes.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 63b1ad24

drivers/kvm/mmu.c

+11 −0
Original line number Diff line number Diff line
@@ -731,6 +731,17 @@ static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn) 
	return r;

}



static void mmu_unshadow(struct kvm_vcpu *vcpu, gfn_t gfn)

{

	struct kvm_mmu_page *page;



	while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) {

		pgprintk("%s: zap %lx %x\n",

			 __FUNCTION__, gfn, page->role.word);

		kvm_mmu_zap_page(vcpu, page);

	}

}



static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)

{

	int slot = memslot_id(kvm, gfn_to_memslot(kvm, gpa >> PAGE_SHIFT));

drivers/kvm/paging_tmpl.h

+57 −111
Original line number Diff line number Diff line
@@ -197,11 +197,26 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu, 
				  gpa_t gaddr,

				  pt_element_t *gpte,

				  u64 access_bits,

				  int user_fault,

				  int write_fault,

				  int *ptwrite,

				  struct guest_walker *walker,

				  gfn_t gfn)

{

	hpa_t paddr;

	int dirty = *gpte & PT_DIRTY_MASK;

	int was_rmapped = is_rmap_pte(*shadow_pte);



	pgprintk("%s: spte %llx gpte %llx access %llx write_fault %d"

		 " user_fault %d gfn %lx\n",

		 __FUNCTION__, *shadow_pte, (u64)*gpte, access_bits,

		 write_fault, user_fault, gfn);



	if (write_fault && !dirty) {

		*gpte |= PT_DIRTY_MASK;

		dirty = 1;

		FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);

	}



	*shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET;

	if (!dirty)
@@ -209,7 +224,9 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu, 


	paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);



	*shadow_pte |= access_bits;

	*shadow_pte |= PT_PRESENT_MASK;

	if (access_bits & PT_USER_MASK)

		*shadow_pte |= PT_USER_MASK;



	if (is_error_hpa(paddr)) {

		*shadow_pte |= gaddr;
@@ -231,9 +248,16 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu, 
		access_bits &= ~PT_WRITABLE_MASK;

	}



	if (access_bits & PT_WRITABLE_MASK) {

	if ((access_bits & PT_WRITABLE_MASK)

	    || (write_fault && !is_write_protection(vcpu) && !user_fault)) {

		struct kvm_mmu_page *shadow;



		*shadow_pte |= PT_WRITABLE_MASK;

		if (user_fault) {

			mmu_unshadow(vcpu, gfn);

			goto unshadowed;

		}



		shadow = kvm_mmu_lookup_page(vcpu, gfn);

		if (shadow) {

			pgprintk("%s: found shadow page for %lx, marking ro\n",
@@ -243,25 +267,31 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu, 
				*shadow_pte &= ~PT_WRITABLE_MASK;

				kvm_arch_ops->tlb_flush(vcpu);

			}

			if (write_fault)

				*ptwrite = 1;

		}

	}



unshadowed:



	if (access_bits & PT_WRITABLE_MASK)

		mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);



	page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);

	if (!was_rmapped)

		rmap_add(vcpu, shadow_pte);

}



static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t *gpte,

			   u64 *shadow_pte, u64 access_bits,

			   int write_fault, gfn_t gfn)

			   int user_fault, int write_fault, int *ptwrite,

			   struct guest_walker *walker, gfn_t gfn)

{

	ASSERT(*shadow_pte == 0);

	access_bits &= *gpte;

	*shadow_pte = (*gpte & PT_PTE_COPY_MASK);

	*shadow_pte |= (*gpte & PT_PTE_COPY_MASK);

	FNAME(set_pte_common)(vcpu, shadow_pte, *gpte & PT_BASE_ADDR_MASK,

			      gpte, access_bits, write_fault, gfn);

			      gpte, access_bits, user_fault, write_fault,

			      ptwrite, walker, gfn);

}



static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
@@ -276,31 +306,34 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page, 
		return;

	pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte);

	FNAME(set_pte)(vcpu, &gpte, spte, PT_USER_MASK | PT_WRITABLE_MASK, 0,

		       0, NULL, NULL,

		       (gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT);

}



static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t *gpde,

			   u64 *shadow_pte, u64 access_bits, int write_fault,

			   gfn_t gfn)

			   u64 *shadow_pte, u64 access_bits,

			   int user_fault, int write_fault, int *ptwrite,

			   struct guest_walker *walker, gfn_t gfn)

{

	gpa_t gaddr;



	ASSERT(*shadow_pte == 0);

	access_bits &= *gpde;

	gaddr = (gpa_t)gfn << PAGE_SHIFT;

	if (PTTYPE == 32 && is_cpuid_PSE36())

		gaddr |= (*gpde & PT32_DIR_PSE36_MASK) <<

			(32 - PT32_DIR_PSE36_SHIFT);

	*shadow_pte = *gpde & PT_PTE_COPY_MASK;

	*shadow_pte |= *gpde & PT_PTE_COPY_MASK;

	FNAME(set_pte_common)(vcpu, shadow_pte, gaddr,

			      gpde, access_bits, write_fault, gfn);

			      gpde, access_bits, user_fault, write_fault,

			      ptwrite, walker, gfn);

}



/*

 * Fetch a shadow pte for a specific level in the paging hierarchy.

 */

static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,

			 struct guest_walker *walker, int write_fault)

			 struct guest_walker *walker,

			 int user_fault, int write_fault, int *ptwrite)

{

	hpa_t shadow_addr;

	int level;
@@ -330,7 +363,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
		shadow_ent = ((u64 *)__va(shadow_addr)) + index;

		if (is_present_pte(*shadow_ent) || is_io_pte(*shadow_ent)) {

			if (level == PT_PAGE_TABLE_LEVEL)

				return shadow_ent;

				break;

			shadow_addr = *shadow_ent & PT64_BASE_ADDR_MASK;

			prev_shadow_ent = shadow_ent;

			continue;
@@ -365,94 +398,17 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
		if (prev_shadow_ent)

			*prev_shadow_ent |= PT_SHADOW_PS_MARK;

		FNAME(set_pde)(vcpu, guest_ent, shadow_ent,

			       walker->inherited_ar, write_fault, walker->gfn);

			       walker->inherited_ar, user_fault, write_fault,

			       ptwrite, walker, walker->gfn);

	} else {

		ASSERT(walker->level == PT_PAGE_TABLE_LEVEL);

		FNAME(set_pte)(vcpu, guest_ent, shadow_ent,

			       walker->inherited_ar,

			       write_fault, walker->gfn);

			       walker->inherited_ar, user_fault, write_fault,

			       ptwrite, walker, walker->gfn);

	}

	return shadow_ent;

}



/*

 * The guest faulted for write.  We need to

 *

 * - check write permissions

 * - update the guest pte dirty bit

 * - update our own dirty page tracking structures

 */

static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,

			       u64 *shadow_ent,

			       struct guest_walker *walker,

			       gva_t addr,

			       int user,

			       int *write_pt)

{

	pt_element_t *guest_ent;

	int writable_shadow;

	gfn_t gfn;

	struct kvm_mmu_page *page;



	if (is_writeble_pte(*shadow_ent))

		return !user || (*shadow_ent & PT_USER_MASK);



	writable_shadow = *shadow_ent & PT_SHADOW_WRITABLE_MASK;

	if (user) {

		/*

		 * User mode access.  Fail if it's a kernel page or a read-only

		 * page.

		 */

		if (!(*shadow_ent & PT_SHADOW_USER_MASK) || !writable_shadow)

			return 0;

		ASSERT(*shadow_ent & PT_USER_MASK);

	} else

		/*

		 * Kernel mode access.  Fail if it's a read-only page and

		 * supervisor write protection is enabled.

		 */

		if (!writable_shadow) {

			if (is_write_protection(vcpu))

				return 0;

			*shadow_ent &= ~PT_USER_MASK;

		}



	guest_ent = walker->ptep;



	if (!is_present_pte(*guest_ent)) {

		*shadow_ent = 0;

		return 0;

	}



	gfn = walker->gfn;



	if (user) {

		/*

		 * Usermode page faults won't be for page table updates.

		 */

		while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) {

			pgprintk("%s: zap %lx %x\n",

				 __FUNCTION__, gfn, page->role.word);

			kvm_mmu_zap_page(vcpu, page);

		}

	} else if (kvm_mmu_lookup_page(vcpu, gfn)) {

		pgprintk("%s: found shadow page for %lx, marking ro\n",

			 __FUNCTION__, gfn);

		mark_page_dirty(vcpu->kvm, gfn);

		FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);

		*guest_ent |= PT_DIRTY_MASK;

		*write_pt = 1;

		return 0;

	}

	mark_page_dirty(vcpu->kvm, gfn);

	*shadow_ent |= PT_WRITABLE_MASK;

	FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);

	*guest_ent |= PT_DIRTY_MASK;

	rmap_add(vcpu, shadow_ent);



	return 1;

}



/*

 * Page fault handler.  There are several causes for a page fault:

 *   - there is no shadow pte for the guest pte
@@ -475,7 +431,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, 
	int fetch_fault = error_code & PFERR_FETCH_MASK;

	struct guest_walker walker;

	u64 *shadow_pte;

	int fixed;

	int write_pt = 0;

	int r;
@@ -503,19 +458,10 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, 
		return 0;

	}



	shadow_pte = FNAME(fetch)(vcpu, addr, &walker, write_fault);

	pgprintk("%s: shadow pte %p %llx\n", __FUNCTION__,

		 shadow_pte, *shadow_pte);



	/*

	 * Update the shadow pte.

	 */

	if (write_fault)

		fixed = FNAME(fix_write_pf)(vcpu, shadow_pte, &walker, addr,

					    user_fault, &write_pt);



	pgprintk("%s: updated shadow pte %p %llx\n", __FUNCTION__,

		 shadow_pte, *shadow_pte);

	shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,

				  &write_pt);

	pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,

		 shadow_pte, *shadow_pte, write_pt);



	FNAME(release_walker)(&walker);