Commit f8232c8c authored by Thomas Huth's avatar Thomas Huth Committed by Christian Borntraeger
Browse files

KVM: s390: Add a function for checking the low-address protection 



The s390 architecture has a special protection mechanism that can
be used to prevent write access to the vital data in the low-core
memory area. This patch adds a new helper function that can be used
to check for such write accesses and in case of protection, it also
sets up the exception data accordingly.

Signed-off-by: default avatarThomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 9a558ee3

arch/s390/kvm/gaccess.c

+28 −0
Original line number Diff line number Diff line
@@ -643,3 +643,31 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra, 
	}

	return rc;

}



/**

 * kvm_s390_check_low_addr_protection - check for low-address protection

 * @ga: Guest address

 *

 * Checks whether an address is subject to low-address protection and set

 * up vcpu->arch.pgm accordingly if necessary.

 *

 * Return: 0 if no protection exception, or PGM_PROTECTION if protected.

 */

int kvm_s390_check_low_addr_protection(struct kvm_vcpu *vcpu, unsigned long ga)

{

	struct kvm_s390_pgm_info *pgm = &vcpu->arch.pgm;

	psw_t *psw = &vcpu->arch.sie_block->gpsw;

	struct trans_exc_code_bits *tec_bits;



	if (!is_low_address(ga) || !low_address_protection_enabled(vcpu))

		return 0;



	memset(pgm, 0, sizeof(*pgm));

	tec_bits = (struct trans_exc_code_bits *)&pgm->trans_exc_code;

	tec_bits->fsi = FSI_STORE;

	tec_bits->as = psw_bits(*psw).as;

	tec_bits->addr = ga >> PAGE_SHIFT;

	pgm->code = PGM_PROTECTION;



	return pgm->code;

}

arch/s390/kvm/gaccess.h

+1 −0
Original line number Diff line number Diff line
@@ -325,5 +325,6 @@ int read_guest_real(struct kvm_vcpu *vcpu, unsigned long gra, void *data, 
}



int ipte_lock_held(struct kvm_vcpu *vcpu);

int kvm_s390_check_low_addr_protection(struct kvm_vcpu *vcpu, unsigned long ga);



#endif /* __KVM_S390_GACCESS_H */

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