[3.19.y-ckt stable] Patch "KVM: s390: fix wrong lookup of VCPUs by array index" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    KVM: s390: fix wrong lookup of VCPUs by array index

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt12.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From a7d4eb163fdfd0b853ab692f660b6b47bf1b2cc1 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <dahi at linux.vnet.ibm.com>
Date: Thu, 5 Nov 2015 09:06:06 +0100
Subject: KVM: s390: fix wrong lookup of VCPUs by array index

commit 152e9f65d66f0a3891efc3869440becc0e7ff53f upstream.

For now, VCPUs were always created sequentially with incrementing
VCPU ids. Therefore, the index in the VCPUs array matched the id.

As sequential creation might change with cpu hotplug, let's use
the correct lookup function to find a VCPU by id, not array index.

Let's also use kvm_lookup_vcpu() for validation of the sending VCPU
on external call injection.

Reviewed-by: Christian Borntraeger <borntraeger at de.ibm.com>
Signed-off-by: David Hildenbrand <dahi at linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger at de.ibm.com>
[ kamal: backport to 3.19-stable: dropped __inject_extcall validation change ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/s390/kvm/sigp.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c
index 6651f9f..7ca07cb 100644
--- a/arch/s390/kvm/sigp.c
+++ b/arch/s390/kvm/sigp.c
@@ -317,12 +317,8 @@ static int handle_sigp_dst(struct kvm_vcpu *vcpu, u8 order_code,
 			   u16 cpu_addr, u32 parameter, u64 *status_reg)
 {
 	int rc;
-	struct kvm_vcpu *dst_vcpu;
+	struct kvm_vcpu *dst_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);

-	if (cpu_addr >= KVM_MAX_VCPUS)
-		return SIGP_CC_NOT_OPERATIONAL;
-
-	dst_vcpu = kvm_get_vcpu(vcpu->kvm, cpu_addr);
 	if (!dst_vcpu)
 		return SIGP_CC_NOT_OPERATIONAL;

@@ -452,7 +448,7 @@ int kvm_s390_handle_sigp_pei(struct kvm_vcpu *vcpu)
 	trace_kvm_s390_handle_sigp_pei(vcpu, order_code, cpu_addr);

 	if (order_code == SIGP_EXTERNAL_CALL) {
-		dest_vcpu = kvm_get_vcpu(vcpu->kvm, cpu_addr);
+		dest_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);
 		BUG_ON(dest_vcpu == NULL);

 		kvm_s390_vcpu_wakeup(dest_vcpu);
--
1.9.1