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authorThomas Huth <thuth@linux.vnet.ibm.com>2014-03-03 23:34:42 +0100
committerChristian Borntraeger <borntraeger@de.ibm.com>2014-04-29 15:01:52 +0200
commitf8232c8cf720074c0eb0804202d424a2b7b4ee76 (patch)
treeee07bdda3663c68fad9cbeaff76935794f3f0286 /arch/s390
parent9a558ee3ccb8afcf43c8d9d4d206ab6de4aa30a2 (diff)
downloadop-kernel-dev-f8232c8cf720074c0eb0804202d424a2b7b4ee76.zip
op-kernel-dev-f8232c8cf720074c0eb0804202d424a2b7b4ee76.tar.gz
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: 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>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/kvm/gaccess.c28
-rw-r--r--arch/s390/kvm/gaccess.h1
2 files changed, 29 insertions, 0 deletions
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 691fdb7..db608c3 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -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;
+}
diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
index 1079c8f..68db43e 100644
--- a/arch/s390/kvm/gaccess.h
+++ b/arch/s390/kvm/gaccess.h
@@ -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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