Commit 589071ea authored by Claudio Imbrenda's avatar Claudio Imbrenda
Browse files

KVM: s390: KVM page table management functions: clear and replace



Add page table management functions to be used for KVM guest (gmap)
page tables.

This patch adds functions to clear, replace or exchange DAT table
entries.

Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
parent 12f2f61a
Loading
Loading
Loading
Loading
+115 −0
Original line number Diff line number Diff line
@@ -101,3 +101,118 @@ void dat_free_level(struct crst_table *table, bool owns_ptes)
	}
	dat_free_crst(table);
}

/**
 * dat_crstep_xchg() - Exchange a gmap CRSTE with another.
 * @crstep: Pointer to the CRST entry
 * @new: Replacement entry.
 * @gfn: The affected guest address.
 * @asce: The ASCE of the address space.
 *
 * Context: This function is assumed to be called with kvm->mmu_lock held.
 */
void dat_crstep_xchg(union crste *crstep, union crste new, gfn_t gfn, union asce asce)
{
	if (crstep->h.i) {
		WRITE_ONCE(*crstep, new);
		return;
	} else if (cpu_has_edat2()) {
		crdte_crste(crstep, *crstep, new, gfn, asce);
		return;
	}

	if (machine_has_tlb_guest())
		idte_crste(crstep, gfn, IDTE_GUEST_ASCE, asce, IDTE_GLOBAL);
	else
		idte_crste(crstep, gfn, 0, NULL_ASCE, IDTE_GLOBAL);
	WRITE_ONCE(*crstep, new);
}

/**
 * dat_crstep_xchg_atomic() - Atomically exchange a gmap CRSTE with another.
 * @crstep: Pointer to the CRST entry.
 * @old: Expected old value.
 * @new: Replacement entry.
 * @gfn: The affected guest address.
 * @asce: The asce of the address space.
 *
 * This function is needed to atomically exchange a CRSTE that potentially
 * maps a prefix area, without having to invalidate it inbetween.
 *
 * Context: This function is assumed to be called with kvm->mmu_lock held.
 *
 * Return: %true if the exchange was successful.
 */
bool dat_crstep_xchg_atomic(union crste *crstep, union crste old, union crste new, gfn_t gfn,
			    union asce asce)
{
	if (old.h.i)
		return arch_try_cmpxchg((long *)crstep, &old.val, new.val);
	if (cpu_has_edat2())
		return crdte_crste(crstep, old, new, gfn, asce);
	return cspg_crste(crstep, old, new);
}

static void dat_set_storage_key_from_pgste(union pte pte, union pgste pgste)
{
	union skey nkey = { .acc = pgste.acc, .fp = pgste.fp };

	page_set_storage_key(pte_origin(pte), nkey.skey, 0);
}

static void dat_move_storage_key(union pte old, union pte new)
{
	page_set_storage_key(pte_origin(new), page_get_storage_key(pte_origin(old)), 1);
}

static union pgste dat_save_storage_key_into_pgste(union pte pte, union pgste pgste)
{
	union skey skey;

	skey.skey = page_get_storage_key(pte_origin(pte));

	pgste.acc = skey.acc;
	pgste.fp = skey.fp;
	pgste.gr |= skey.r;
	pgste.gc |= skey.c;

	return pgste;
}

union pgste __dat_ptep_xchg(union pte *ptep, union pgste pgste, union pte new, gfn_t gfn,
			    union asce asce, bool uses_skeys)
{
	union pte old = READ_ONCE(*ptep);

	/* Updating only the software bits while holding the pgste lock. */
	if (!((ptep->val ^ new.val) & ~_PAGE_SW_BITS)) {
		WRITE_ONCE(ptep->swbyte, new.swbyte);
		return pgste;
	}

	if (!old.h.i) {
		unsigned long opts = IPTE_GUEST_ASCE | (pgste.nodat ? IPTE_NODAT : 0);

		if (machine_has_tlb_guest())
			__ptep_ipte(gfn_to_gpa(gfn), (void *)ptep, opts, asce.val, IPTE_GLOBAL);
		else
			__ptep_ipte(gfn_to_gpa(gfn), (void *)ptep, 0, 0, IPTE_GLOBAL);
	}

	if (uses_skeys) {
		if (old.h.i && !new.h.i)
			/* Invalid to valid: restore storage keys from PGSTE. */
			dat_set_storage_key_from_pgste(new, pgste);
		else if (!old.h.i && new.h.i)
			/* Valid to invalid: save storage keys to PGSTE. */
			pgste = dat_save_storage_key_into_pgste(old, pgste);
		else if (!old.h.i && !new.h.i)
			/* Valid to valid: move storage keys. */
			if (old.h.pfra != new.h.pfra)
				dat_move_storage_key(old, new);
		/* Invalid to invalid: nothing to do. */
	}

	WRITE_ONCE(*ptep, new);
	return pgste;
}
+40 −0
Original line number Diff line number Diff line
@@ -430,6 +430,12 @@ struct kvm_s390_mmu_cache {
	short int n_rmaps;
};

union pgste __must_check __dat_ptep_xchg(union pte *ptep, union pgste pgste, union pte new,
					 gfn_t gfn, union asce asce, bool uses_skeys);
bool dat_crstep_xchg_atomic(union crste *crstep, union crste old, union crste new, gfn_t gfn,
			    union asce asce);
void dat_crstep_xchg(union crste *crstep, union crste new, gfn_t gfn, union asce asce);

void dat_free_level(struct crst_table *table, bool owns_ptes);
struct crst_table *dat_alloc_crst_sleepable(unsigned long init);

@@ -757,6 +763,21 @@ static inline void pgste_set_unlock(union pte *ptep, union pgste pgste)
	WRITE_ONCE(*pgste_of(ptep), pgste);
}

static inline void dat_ptep_xchg(union pte *ptep, union pte new, gfn_t gfn, union asce asce,
				 bool has_skeys)
{
	union pgste pgste;

	pgste = pgste_get_lock(ptep);
	pgste = __dat_ptep_xchg(ptep, pgste, new, gfn, asce, has_skeys);
	pgste_set_unlock(ptep, pgste);
}

static inline void dat_ptep_clear(union pte *ptep, gfn_t gfn, union asce asce, bool has_skeys)
{
	dat_ptep_xchg(ptep, _PTE_EMPTY, gfn, asce, has_skeys);
}

static inline void dat_free_pt(struct page_table *pt)
{
	free_page((unsigned long)pt);
@@ -794,4 +815,23 @@ static inline struct kvm_s390_mmu_cache *kvm_s390_new_mmu_cache(void)
	return NULL;
}

static inline bool dat_pmdp_xchg_atomic(union pmd *pmdp, union pmd old, union pmd new,
					gfn_t gfn, union asce asce)
{
	return dat_crstep_xchg_atomic(_CRSTEP(pmdp), _CRSTE(old), _CRSTE(new), gfn, asce);
}

static inline bool dat_pudp_xchg_atomic(union pud *pudp, union pud old, union pud new,
					gfn_t gfn, union asce asce)
{
	return dat_crstep_xchg_atomic(_CRSTEP(pudp), _CRSTE(old), _CRSTE(new), gfn, asce);
}

static inline void dat_crstep_clear(union crste *crstep, gfn_t gfn, union asce asce)
{
	union crste newcrste = _CRSTE_EMPTY(crstep->h.tt);

	dat_crstep_xchg(crstep, newcrste, gfn, asce);
}

#endif /* __KVM_S390_DAT_H */