Patch "KVM: s390: correct fprs on SIGP (STOP AND) STORE STATUS" has been added to the 4.4-stable tree

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

KVM: s390: correct fprs on SIGP (STOP AND) STORE STATUS

to the 4.4-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-correct-fprs-on-sigp-stop-and-store-status.patch
and it can be found in the queue-4.4 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: Tue, 8 Mar 2016 12:24:30 +0100
Subject: KVM: s390: correct fprs on SIGP (STOP AND) STORE STATUS

From: David Hildenbrand <[email protected]>

commit 9522b37f5a8c7bfabe46eecadf2e130f1103f337 upstream.

With MACHINE_HAS_VX, we convert the floating point registers from the vector registeres when storing the status. For other VCPUs, these are stored to vcpu->run->s.regs.vrs, but we are using current->thread.fpu.vxrs, which resolves to the currently loaded VCPU.

So kvm_s390_store_status_unloaded() currently writes the wrong floating point registers (converted from the vector registers) when called from another VCPU on a z13.

This is only the case for old user space not handling SIGP STORE STATUS and SIGP STOP AND STORE STATUS, but relying on the kernel implementation. All other calls come from the loaded VCPU via kvm_s390_store_status().

---
 arch/s390/kvm/kvm-s390.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -2249,7 +2249,7 @@ int kvm_s390_store_status_unloaded(struc
 
 	/* manually convert vector registers if necessary */
 	if (MACHINE_HAS_VX) {
-		convert_vx_to_fp(fprs, current->thread.fpu.vxrs);
+		convert_vx_to_fp(fprs, (__vector128 *) vcpu->run->s.regs.vrs);
 		rc = write_guest_abs(vcpu, gpa + __LC_FPREGS_SAVE_AREA,
 				     fprs, 128);
 	} else {

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

queue-4.4/kvm-s390-correct-fprs-on-sigp-stop-and-store-status.patch