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

arch/s390/kvm/dat.c

+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;

}

arch/s390/kvm/dat.h

+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 */