From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christian Borntraeger , Jens Freimann , David Hildenbrand Subject: [PATCH 4.1 44/56] KVM: s390: fix external call injection without sigp interpretation Date: Wed, 8 Jul 2015 00:35:33 -0700 Message-Id: <20150708073240.335810431@linuxfoundation.org> In-Reply-To: <20150708073237.780280770@linuxfoundation.org> References: <20150708073237.780280770@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Hildenbrand commit b938eacea0b6881f2116a061e6da3ec840e75137 upstream. Commit ea5f49692575 ("KVM: s390: only one external call may be pending at a time") introduced a bug on machines that don't have SIGP interpretation facility installed. The injection of an external call will now always fail with -EBUSY (if none is already pending). This leads to the following symptoms: - An external call will be injected but with the wrong "src cpu id", as this id will not be remembered. - The target vcpu will not be woken up, therefore the guest will hang if it cannot deal with unexpected failures of the SIGP EXTERNAL CALL instruction. - If an external call is already pending, -EBUSY will not be reported. Reviewed-by: Christian Borntraeger Reviewed-by: Jens Freimann Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman --- arch/s390/kvm/interrupt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -1061,7 +1061,7 @@ static int __inject_extcall(struct kvm_v if (sclp_has_sigpif()) return __inject_extcall_sigpif(vcpu, src_id); - if (!test_and_set_bit(IRQ_PEND_EXT_EXTERNAL, &li->pending_irqs)) + if (test_and_set_bit(IRQ_PEND_EXT_EXTERNAL, &li->pending_irqs)) return -EBUSY; *extcall = irq->u.extcall; atomic_set_mask(CPUSTAT_EXT_INT, li->cpuflags);