[PATCH 0/1] KVM: s390: last minute fix for 4.5

[PATCH 0/1] KVM: s390: last minute fix for 4.5

[Christian Borntraeger]

Paolo,

one last fixup for KVM on s390 for 4.5. It fixes the
sigp store status of floating registers with older QEMU
versions that still rely on the kernel for doing so.

David Hildenbrand (1):
  KVM: s390: correct fprs on SIGP (STOP AND) STORE STATUS

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

-- 
2.3.0

[PATCH 1/1] KVM: s390: correct fprs on SIGP (STOP AND) STORE STATUS

[Christian Borntraeger]

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

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().

Fixes: 9abc2a08a7d6 (KVM: s390: fix memory overwrites when vx is disabled)
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: stable@vger.kernel.org # v4.4+
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 4af21c7..03dfe9c 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2381,7 +2381,7 @@ int kvm_s390_store_status_unloaded(struct kvm_vcpu *vcpu, unsigned long gpa)
 
 	/* 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 {
-- 
2.3.0

Re: [PATCH 0/1] KVM: s390: last minute fix for 4.5

[Paolo Bonzini]

On 08/03/2016 12:24, Christian Borntraeger wrote:
> Paolo,
> 
> one last fixup for KVM on s390 for 4.5. It fixes the
> sigp store status of floating registers with older QEMU
> versions that still rely on the kernel for doing so.
> 
> David Hildenbrand (1):
>   KVM: s390: correct fprs on SIGP (STOP AND) STORE STATUS
> 
>  arch/s390/kvm/kvm-s390.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Applied, thanks.

Paolo