[3.16.y-ckt stable] Patch "MIPS: KVM: Fix CACHE immediate offset sign extension" has been added to staging queue

[Luis Henriques]

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

    MIPS: KVM: Fix CACHE immediate offset sign extension

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt22.

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

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From fe63200740dcbf3cdda3388aff854136ad558b67 Mon Sep 17 00:00:00 2001
From: James Hogan <james.hogan at imgtec.com>
Date: Wed, 11 Nov 2015 14:21:19 +0000
Subject: MIPS: KVM: Fix CACHE immediate offset sign extension

commit c5c2a3b998f1ff5a586f9d37e154070b8d550d17 upstream.

The immediate field of the CACHE instruction is signed, so ensure that
it gets sign extended by casting it to an int16_t rather than just
masking the low 16 bits.

Fixes: e685c689f3a8 ("KVM/MIPS32: Privileged instruction/target branch emulation.")
Signed-off-by: James Hogan <james.hogan at imgtec.com>
Cc: Ralf Baechle <ralf at linux-mips.org>
Cc: Paolo Bonzini <pbonzini at redhat.com>
Cc: Gleb Natapov <gleb at kernel.org>
Cc: linux-mips at linux-mips.org
Cc: kvm at vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
[ luis: backported to 3.16:
  - file rename: emulate.c -> kvm_mips_emul.c ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/mips/kvm/kvm_mips_emul.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c
index 18b4e2fdae33..950229176c2f 100644
--- a/arch/mips/kvm/kvm_mips_emul.c
+++ b/arch/mips/kvm/kvm_mips_emul.c
@@ -1434,7 +1434,7 @@ kvm_mips_emulate_cache(uint32_t inst, uint32_t *opc, uint32_t cause,

 	base = (inst >> 21) & 0x1f;
 	op_inst = (inst >> 16) & 0x1f;
-	offset = inst & 0xffff;
+	offset = (int16_t)inst;
 	cache = (inst >> 16) & 0x3;
 	op = (inst >> 18) & 0x7;