Commit e0506bcb authored by Izik Eidus's avatar Izik Eidus Committed by Avi Kivity
Browse files

KVM: Change kvm_{read,write}_guest() to use copy_{from,to}_user() 



This changes kvm_write_guest_page/kvm_read_guest_page to use
copy_to_user/read_from_user, as a result we get better speed
and better dirty bit tracking.

Signed-off-by: default avatarIzik Eidus <izike@qumranet.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 539cb660

drivers/kvm/kvm_main.c

+14 −24
Original line number Diff line number Diff line
@@ -630,20 +630,15 @@ static int next_segment(unsigned long len, int offset) 
int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,

			int len)

{

	void *page_virt;

	struct page *page;

	int r;

	unsigned long addr;



	page = gfn_to_page(kvm, gfn);

	if (is_error_page(page)) {

		kvm_release_page(page);

	addr = gfn_to_hva(kvm, gfn);

	if (kvm_is_error_hva(addr))

		return -EFAULT;

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

	if (r)

		return -EFAULT;

	}

	page_virt = kmap_atomic(page, KM_USER0);



	memcpy(data, page_virt + offset, len);



	kunmap_atomic(page_virt, KM_USER0);

	kvm_release_page(page);

	return 0;

}

EXPORT_SYMBOL_GPL(kvm_read_guest_page);
@@ -671,21 +666,16 @@ EXPORT_SYMBOL_GPL(kvm_read_guest); 
int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,

			 int offset, int len)

{

	void *page_virt;

	struct page *page;

	int r;

	unsigned long addr;



	page = gfn_to_page(kvm, gfn);

	if (is_error_page(page)) {

		kvm_release_page(page);

	addr = gfn_to_hva(kvm, gfn);

	if (kvm_is_error_hva(addr))

		return -EFAULT;

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

	if (r)

		return -EFAULT;

	}

	page_virt = kmap_atomic(page, KM_USER0);



	memcpy(page_virt + offset, data, len);



	kunmap_atomic(page_virt, KM_USER0);

	mark_page_dirty(kvm, gfn);

	kvm_release_page(page);

	return 0;

}

EXPORT_SYMBOL_GPL(kvm_write_guest_page);