Commit 857b8de9 authored Aug 03, 2017 by Heiko Carstens Committed by Christian Borntraeger Aug 21, 2017

KVM: s390: sthyi: fix specification exception detection



sthyi should only generate a specification exception if the function
code is zero and the response buffer is not on a 4k boundary.

The current code would also test for unknown function codes if the
response buffer, that is currently only defined for function code 0,
is not on a 4k boundary and incorrectly inject a specification
exception instead of returning with condition code 3 and return code 4
(unsupported function code).

Fix this by moving the boundary check.

Fixes: 95ca2cb5 ("KVM: s390: Add sthyi emulation")
Cc: <stable@vger.kernel.org> # 4.8+
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

parent 4a4eefcd

arch/s390/kvm/sthyi.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -425,7 +425,7 @@ int handle_sthyi(struct kvm_vcpu *vcpu)
		VCPU_EVENT(vcpu, 3, "STHYI: fc: %llu addr: 0x%016llx", code, addr);
		trace_kvm_s390_handle_sthyi(vcpu, code, addr);

		if (reg1 == reg2 \|\| reg1 & 1 \|\| reg2 & 1 \|\| addr & ~PAGE_MASK)
		if (reg1 == reg2 \|\| reg1 & 1 \|\| reg2 & 1)
		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);

		if (code & 0xffff) {
		@@ -433,6 +433,9 @@ int handle_sthyi(struct kvm_vcpu *vcpu)
		goto out;
		}

		if (addr & ~PAGE_MASK)
		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);

		/*
		* If the page has not yet been faulted in, we want to do that
		* now and not after all the expensive calculations.

Admin message