Commit 2fc84311 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

KVM: reorganize hva_to_pfn 



We do too many things in hva_to_pfn, this patch reorganize the code,
let it be better readable

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 86ab8cff

virt/kvm/kvm_main.c

+97 −62
Original line number Diff line number Diff line
@@ -1041,25 +1041,41 @@ static inline int check_user_page_hwpoison(unsigned long addr) 
	return rc == -EHWPOISON;

}



static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,

			bool write_fault, bool *writable)

/*

 * The atomic path to get the writable pfn which will be stored in @pfn,

 * true indicates success, otherwise false is returned.

 */

static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async,

			    bool write_fault, bool *writable, pfn_t *pfn)

{

	struct page *page[1];

	int npages = 0;

	pfn_t pfn;

	int npages;



	/* we can do it either atomically or asynchronously, not both */

	BUG_ON(atomic && async);

	if (!(async || atomic))

		return false;



	BUG_ON(!write_fault && !writable);

	npages = __get_user_pages_fast(addr, 1, 1, page);

	if (npages == 1) {

		*pfn = page_to_pfn(page[0]);



		if (writable)

			*writable = true;

		return true;

	}



	if (atomic || async)

		npages = __get_user_pages_fast(addr, 1, 1, page);

	return false;

}



/*

 * The slow path to get the pfn of the specified host virtual address,

 * 1 indicates success, -errno is returned if error is detected.

 */

static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,

			   bool *writable, pfn_t *pfn)

{

	struct page *page[1];

	int npages = 0;



	if (unlikely(npages != 1) && !atomic) {

	might_sleep();



	if (writable)
@@ -1073,9 +1089,11 @@ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, 
	} else

		npages = get_user_pages_fast(addr, 1, write_fault,

					     page);

	if (npages != 1)

		return npages;



	/* map read fault as writable if possible */

		if (unlikely(!write_fault) && npages == 1) {

	if (unlikely(!write_fault)) {

		struct page *wpage[1];



		npages = __get_user_pages_fast(addr, 1, 1, wpage);
@@ -1084,21 +1102,40 @@ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, 
			put_page(page[0]);

			page[0] = wpage[0];

		}



		npages = 1;

	}

	*pfn = page_to_pfn(page[0]);

	return npages;

}



	if (unlikely(npages != 1)) {

static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,

			bool write_fault, bool *writable)

{

	struct vm_area_struct *vma;

	pfn_t pfn = 0;

	int npages;



	/* we can do it either atomically or asynchronously, not both */

	BUG_ON(atomic && async);



	BUG_ON(!write_fault && !writable);



	if (hva_to_pfn_fast(addr, atomic, async, write_fault, writable, &pfn))

		return pfn;



	if (atomic)

		return KVM_PFN_ERR_FAULT;



	npages = hva_to_pfn_slow(addr, async, write_fault, writable, &pfn);

	if (npages == 1)

		return pfn;



	down_read(&current->mm->mmap_sem);

	if (npages == -EHWPOISON ||

	      (!async && check_user_page_hwpoison(addr))) {

			up_read(&current->mm->mmap_sem);

			return KVM_PFN_ERR_HWPOISON;

		pfn = KVM_PFN_ERR_HWPOISON;

		goto exit;

	}



	vma = find_vma_intersection(current->mm, addr, addr + 1);
@@ -1114,10 +1151,8 @@ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, 
			*async = true;

		pfn = KVM_PFN_ERR_FAULT;

	}

exit:

	up_read(&current->mm->mmap_sem);

	} else

		pfn = page_to_pfn(page[0]);



	return pfn;

}