This is a note to let you know that I've just added the patch titled
KVM: s390: enable SIMD only when no VCPUs were created
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-enable-simd-only-when-no-vcpus-were-created.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 5967c17b118a2bd1dd1d554cc4eee16233e52bec Mon Sep 17 00:00:00 2001
From: David Hildenbrand <[email protected]>
Date: Fri, 6 Nov 2015 12:08:48 +0100
Subject: KVM: s390: enable SIMD only when no VCPUs were created
From: David Hildenbrand <[email protected]>
commit 5967c17b118a2bd1dd1d554cc4eee16233e52bec upstream.
We should never allow to enable/disable any facilities for the guest
when other VCPUs were already created.
kvm_arch_vcpu_(load|put) relies on SIMD not changing during runtime.
If somebody would create and run VCPUs and then decides to enable
SIMD, undefined behaviour could be possible (e.g. vector save area
not being set up).
Acked-by: Christian Borntraeger <[email protected]>
Acked-by: Cornelia Huck <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
Signed-off-by: Christian Borntraeger <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/s390/kvm/kvm-s390.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -342,12 +342,16 @@ static int kvm_vm_ioctl_enable_cap(struc
r = 0;
break;
case KVM_CAP_S390_VECTOR_REGISTERS:
- if (MACHINE_HAS_VX) {
+ mutex_lock(&kvm->lock);
+ if (atomic_read(&kvm->online_vcpus)) {
+ r = -EBUSY;
+ } else if (MACHINE_HAS_VX) {
set_kvm_facility(kvm->arch.model.fac->mask, 129);
set_kvm_facility(kvm->arch.model.fac->list, 129);
r = 0;
} else
r = -EINVAL;
+ mutex_unlock(&kvm->lock);
VM_EVENT(kvm, 3, "ENABLE: CAP_S390_VECTOR_REGISTERS %s",
r ? "(not available)" : "(success)");
break;
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
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