Patch "KVM: s390: fix wrong lookup of VCPUs by array index" has been added to the 4.3-stable tree

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

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

to the 4.3-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-wrong-lookup-of-vcpus-by-array-index.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: David Hildenbrand <[email protected]>
Date: Thu, 5 Nov 2015 09:06:06 +0100
Subject: KVM: s390: fix wrong lookup of VCPUs by array index

From: David Hildenbrand <[email protected]>

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.

---
 arch/s390/kvm/interrupt.c |    3 +--
 arch/s390/kvm/sigp.c      |    8 ++------
 2 files changed, 3 insertions(+), 8 deletions(-)

@@ -1057,8 +1057,7 @@ static int __inject_extcall(struct kvm_v
 				   src_id, 0);
 
 	/* sending vcpu invalid */
-	if (src_id >= KVM_MAX_VCPUS ||
-	    kvm_get_vcpu(vcpu->kvm, src_id) == NULL)
+	if (kvm_get_vcpu_by_id(vcpu->kvm, src_id) == NULL)
 		return -EINVAL;
 
 	if (sclp.has_sigpif)

@@ -291,12 +291,8 @@ static int handle_sigp_dst(struct kvm_vc
 			   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;
 

@@ -478,7 +474,7 @@ int kvm_s390_handle_sigp_pei(struct kvm_
 	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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.3/kvm-s390-sca-must-not-cross-page-boundaries.patch queue-4.3/kvm-s390-enable-simd-only-when-no-vcpus-were-created.patch queue-4.3/kvm-s390-fix-wrong-lookup-of-vcpus-by-array-index.patch queue-4.3/kvm-s390-avoid-memory-overwrites-on-emergency-signal-injection.patch