Commit ac79c978 authored by Avi Kivity's avatar Avi Kivity Committed by Linus Torvalds
Browse files

[PATCH] KVM: MMU: Fold fetch_guest() into init_walker() 



It is never necessary to fetch a guest entry from an intermediate page table
level (except for large pages), so avoid some confusion by always descending
into the lowest possible level.

Rename init_walker() to walk_addr() as it is no longer restricted to
initialization.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 1342d353

drivers/kvm/paging_tmpl.h

+47 −58
Original line number Diff line number Diff line
@@ -54,14 +54,19 @@ struct guest_walker { 
	int level;

	gfn_t table_gfn;

	pt_element_t *table;

	pt_element_t *ptep;

	pt_element_t inherited_ar;

};



static void FNAME(init_walker)(struct guest_walker *walker,

			       struct kvm_vcpu *vcpu)

/*

 * Fetch a guest pte for a guest virtual address

 */

static void FNAME(walk_addr)(struct guest_walker *walker,

			     struct kvm_vcpu *vcpu, gva_t addr)

{

	hpa_t hpa;

	struct kvm_memory_slot *slot;

	pt_element_t *ptep;



	walker->level = vcpu->mmu.root_level;

	walker->table_gfn = (vcpu->cr3 & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
@@ -75,6 +80,38 @@ static void FNAME(init_walker)(struct guest_walker *walker, 
	walker->table = (pt_element_t *)( (unsigned long)walker->table |

		(unsigned long)(vcpu->cr3 & ~(PAGE_MASK | CR3_FLAGS_MASK)) );

	walker->inherited_ar = PT_USER_MASK | PT_WRITABLE_MASK;



	for (;;) {

		int index = PT_INDEX(addr, walker->level);

		hpa_t paddr;



		ptep = &walker->table[index];

		ASSERT(((unsigned long)walker->table & PAGE_MASK) ==

		       ((unsigned long)ptep & PAGE_MASK));



		/* Don't set accessed bit on PAE PDPTRs */

		if (vcpu->mmu.root_level != 3 || walker->level != 3)

			if ((*ptep & (PT_PRESENT_MASK | PT_ACCESSED_MASK))

			    == PT_PRESENT_MASK)

				*ptep |= PT_ACCESSED_MASK;



		if (!is_present_pte(*ptep) ||

		    walker->level == PT_PAGE_TABLE_LEVEL ||

		    (walker->level == PT_DIRECTORY_LEVEL &&

		     (*ptep & PT_PAGE_SIZE_MASK) &&

		     (PTTYPE == 64 || is_pse(vcpu))))

			break;



		if (walker->level != 3 || is_long_mode(vcpu))

			walker->inherited_ar &= walker->table[index];

		walker->table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;

		paddr = safe_gpa_to_hpa(vcpu, *ptep & PT_BASE_ADDR_MASK);

		kunmap_atomic(walker->table, KM_USER0);

		walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT),

					    KM_USER0);

		--walker->level;

	}

	walker->ptep = ptep;

}



static void FNAME(release_walker)(struct guest_walker *walker)
@@ -109,41 +146,6 @@ static void FNAME(set_pde)(struct kvm_vcpu *vcpu, u64 guest_pde, 
		       guest_pde & PT_DIRTY_MASK, access_bits);

}



/*

 * Fetch a guest pte from a specific level in the paging hierarchy.

 */

static pt_element_t *FNAME(fetch_guest)(struct kvm_vcpu *vcpu,

					struct guest_walker *walker,

					int level,

					gva_t addr)

{



	ASSERT(level > 0  && level <= walker->level);



	for (;;) {

		int index = PT_INDEX(addr, walker->level);

		hpa_t paddr;



		ASSERT(((unsigned long)walker->table & PAGE_MASK) ==

		       ((unsigned long)&walker->table[index] & PAGE_MASK));

		if (level == walker->level ||

		    !is_present_pte(walker->table[index]) ||

		    (walker->level == PT_DIRECTORY_LEVEL &&

		     (walker->table[index] & PT_PAGE_SIZE_MASK) &&

		     (PTTYPE == 64 || is_pse(vcpu))))

			return &walker->table[index];

		if (walker->level != 3 || is_long_mode(vcpu))

			walker->inherited_ar &= walker->table[index];

		walker->table_gfn = (walker->table[index] & PT_BASE_ADDR_MASK)

			>> PAGE_SHIFT;

		paddr = safe_gpa_to_hpa(vcpu, walker->table[index] & PT_BASE_ADDR_MASK);

		kunmap_atomic(walker->table, KM_USER0);

		walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT),

					    KM_USER0);

		--walker->level;

	}

}



/*

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

 */
@@ -153,6 +155,10 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
	hpa_t shadow_addr;

	int level;

	u64 *prev_shadow_ent = NULL;

	pt_element_t *guest_ent = walker->ptep;



	if (!is_present_pte(*guest_ent))

		return NULL;



	shadow_addr = vcpu->mmu.root_hpa;

	level = vcpu->mmu.shadow_root_level;
@@ -160,7 +166,6 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
	for (; ; level--) {

		u32 index = SHADOW_PT_INDEX(addr, level);

		u64 *shadow_ent = ((u64 *)__va(shadow_addr)) + index;

		pt_element_t *guest_ent;

		u64 shadow_pte;



		if (is_present_pte(*shadow_ent) || is_io_pte(*shadow_ent)) {
@@ -171,21 +176,6 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
			continue;

		}



		if (PTTYPE == 32 && level > PT32_ROOT_LEVEL) {

			ASSERT(level == PT32E_ROOT_LEVEL);

			guest_ent = FNAME(fetch_guest)(vcpu, walker,

						       PT32_ROOT_LEVEL, addr);

		} else

			guest_ent = FNAME(fetch_guest)(vcpu, walker,

						       level, addr);



		if (!is_present_pte(*guest_ent))

			return NULL;



		/* Don't set accessed bit on PAE PDPTRs */

		if (vcpu->mmu.root_level != 3 || walker->level != 3)

			*guest_ent |= PT_ACCESSED_MASK;



		if (level == PT_PAGE_TABLE_LEVEL) {



			if (walker->level == PT_DIRECTORY_LEVEL) {
@@ -253,7 +243,7 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu, 
			*shadow_ent &= ~PT_USER_MASK;

		}



	guest_ent = FNAME(fetch_guest)(vcpu, walker, PT_PAGE_TABLE_LEVEL, addr);

	guest_ent = walker->ptep;



	if (!is_present_pte(*guest_ent)) {

		*shadow_ent = 0;
@@ -296,7 +286,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, 
	 * Look up the shadow pte for the faulting address.

	 */

	for (;;) {

		FNAME(init_walker)(&walker, vcpu);

		FNAME(walk_addr)(&walker, vcpu, addr);

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

		if (IS_ERR(shadow_pte)) {  /* must be -ENOMEM */

			nonpaging_flush(vcpu);
@@ -357,9 +347,8 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr) 
	pt_element_t guest_pte;

	gpa_t gpa;



	FNAME(init_walker)(&walker, vcpu);

	guest_pte = *FNAME(fetch_guest)(vcpu, &walker, PT_PAGE_TABLE_LEVEL,

					vaddr);

	FNAME(walk_addr)(&walker, vcpu, vaddr);

	guest_pte = *walker.ptep;

	FNAME(release_walker)(&walker);



	if (!is_present_pte(guest_pte))

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