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Commit 7ec54588 authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Avi Kivity
Browse files

KVM: Add kvm_read_guest_atomic() 



In preparation for a mmu spinlock, add kvm_read_guest_atomic()
and use it in fetch() and prefetch_page().

Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 10589a46

arch/x86/kvm/paging_tmpl.h

+16 −12
Original line number Diff line number Diff line
@@ -316,10 +316,12 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
					       metaphysical, access,

					       shadow_ent, &new_page);

		if (new_page && !metaphysical) {

			int r;

			pt_element_t curr_pte;

			kvm_read_guest(vcpu->kvm, walker->pte_gpa[level - 2],

			r = kvm_read_guest_atomic(vcpu->kvm,

						  walker->pte_gpa[level - 2],

						  &curr_pte, sizeof(curr_pte));

			if (curr_pte != walker->ptes[level - 2])

			if (r || curr_pte != walker->ptes[level - 2])

				return NULL;

		}

		shadow_addr = __pa(shadow_page->spt);
@@ -429,9 +431,8 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr) 
static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,

				 struct kvm_mmu_page *sp)

{

	int i, offset = 0;

	pt_element_t *gpt;

	struct page *page;

	int i, offset = 0, r = 0;

	pt_element_t pt;



	if (sp->role.metaphysical

	    || (PTTYPE == 32 && sp->role.level > PT_PAGE_TABLE_LEVEL)) {
@@ -441,15 +442,18 @@ static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu, 


	if (PTTYPE == 32)

		offset = sp->role.quadrant << PT64_LEVEL_BITS;

	page = gfn_to_page(vcpu->kvm, sp->gfn);

	gpt = kmap_atomic(page, KM_USER0);

	for (i = 0; i < PT64_ENT_PER_PAGE; ++i)

		if (is_present_pte(gpt[offset + i]))



	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {

		gpa_t pte_gpa = gfn_to_gpa(sp->gfn);

		pte_gpa += (i+offset) * sizeof(pt_element_t);



		r = kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &pt,

					  sizeof(pt_element_t));

		if (r || is_present_pte(pt))

			sp->spt[i] = shadow_trap_nonpresent_pte;

		else

			sp->spt[i] = shadow_notrap_nonpresent_pte;

	kunmap_atomic(gpt, KM_USER0);

	kvm_release_page_clean(page);

	}

}



#undef pt_element_t

include/linux/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -167,6 +167,8 @@ void kvm_release_page_clean(struct page *page); 
void kvm_release_page_dirty(struct page *page);

int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,

			int len);

int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,

			  unsigned long len);

int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len);

int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,

			 int offset, int len);

virt/kvm/kvm_main.c

+20 −0
Original line number Diff line number Diff line
@@ -541,6 +541,26 @@ int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len) 
}

EXPORT_SYMBOL_GPL(kvm_read_guest);



int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,

			  unsigned long len)

{

	int r;

	unsigned long addr;

	gfn_t gfn = gpa >> PAGE_SHIFT;

	int offset = offset_in_page(gpa);



	addr = gfn_to_hva(kvm, gfn);

	if (kvm_is_error_hva(addr))

		return -EFAULT;

	pagefault_disable();

	r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);

	pagefault_enable();

	if (r)

		return -EFAULT;

	return 0;

}

EXPORT_SYMBOL(kvm_read_guest_atomic);



int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,

			 int offset, int len)

{