int pgste_perform_essa()

in mm/pgtable.c [1020:1113]

• 83 lines of code
• 22 McCabe index (conditional complexity)

int pgste_perform_essa(struct mm_struct *mm, unsigned long hva, int orc,
			unsigned long *oldpte, unsigned long *oldpgste)
{
	struct vm_area_struct *vma;
	unsigned long pgstev;
	spinlock_t *ptl;
	pgste_t pgste;
	pte_t *ptep;
	int res = 0;

	WARN_ON_ONCE(orc > ESSA_MAX);
	if (unlikely(orc > ESSA_MAX))
		return -EINVAL;

	vma = vma_lookup(mm, hva);
	if (!vma || is_vm_hugetlb_page(vma))
		return -EFAULT;
	ptep = get_locked_pte(mm, hva, &ptl);
	if (unlikely(!ptep))
		return -EFAULT;
	pgste = pgste_get_lock(ptep);
	pgstev = pgste_val(pgste);
	if (oldpte)
		*oldpte = pte_val(*ptep);
	if (oldpgste)
		*oldpgste = pgstev;

	switch (orc) {
	case ESSA_GET_STATE:
		break;
	case ESSA_SET_STABLE:
		pgstev &= ~(_PGSTE_GPS_USAGE_MASK | _PGSTE_GPS_NODAT);
		pgstev |= _PGSTE_GPS_USAGE_STABLE;
		break;
	case ESSA_SET_UNUSED:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_UNUSED;
		if (pte_val(*ptep) & _PAGE_INVALID)
			res = 1;
		break;
	case ESSA_SET_VOLATILE:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
		if (pte_val(*ptep) & _PAGE_INVALID)
			res = 1;
		break;
	case ESSA_SET_POT_VOLATILE:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		if (!(pte_val(*ptep) & _PAGE_INVALID)) {
			pgstev |= _PGSTE_GPS_USAGE_POT_VOLATILE;
			break;
		}
		if (pgstev & _PGSTE_GPS_ZERO) {
			pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
			break;
		}
		if (!(pgstev & PGSTE_GC_BIT)) {
			pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
			res = 1;
			break;
		}
		break;
	case ESSA_SET_STABLE_RESIDENT:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_STABLE;
		/*
		 * Since the resident state can go away any time after this
		 * call, we will not make this page resident. We can revisit
		 * this decision if a guest will ever start using this.
		 */
		break;
	case ESSA_SET_STABLE_IF_RESIDENT:
		if (!(pte_val(*ptep) & _PAGE_INVALID)) {
			pgstev &= ~_PGSTE_GPS_USAGE_MASK;
			pgstev |= _PGSTE_GPS_USAGE_STABLE;
		}
		break;
	case ESSA_SET_STABLE_NODAT:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_STABLE | _PGSTE_GPS_NODAT;
		break;
	default:
		/* we should never get here! */
		break;
	}
	/* If we are discarding a page, set it to logical zero */
	if (res)
		pgstev |= _PGSTE_GPS_ZERO;

	pgste_val(pgste) = pgstev;
	pgste_set_unlock(ptep, pgste);
	pte_unmap_unlock(ptep, ptl);
	return res;
}