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

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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: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Thomas Huth 2014-03-03 23:34:42 +01:00 • committed by Christian Borntraeger
parent 9a558ee3cc
commit f8232c8cf7
2 changed files with 29 additions and 0 deletions
arch/s390/kvm
gaccess.cgaccess.h

28
arch/s390/kvm/gaccess.c
View file

@ -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;
}

1
arch/s390/kvm/gaccess.h
View file

@ -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 */