Patch "KVM: s390: fix external call injection without sigp interpretation" has been added to the 4.0-stable tree

Patch "KVM: s390: fix external call injection without sigp interpretation" has been added to the 4.0-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    KVM: s390: fix external call injection without sigp interpretation

to the 4.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-s390-fix-external-call-injection-without-sigp-interpretation.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b938eacea0b6881f2116a061e6da3ec840e75137 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <dahi@linux.vnet.ibm.com>
Date: Thu, 30 Apr 2015 13:33:59 +0200
Subject: KVM: s390: fix external call injection without sigp interpretation

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

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 <borntraeger@de.ibm.com>
Reviewed-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -1037,7 +1037,7 @@ 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);


Patches currently in stable-queue which might be from dahi@linux.vnet.ibm.com are

queue-4.0/kvm-s390-fix-external-call-injection-without-sigp-interpretation.patch