From 7f958a52f5e8e4dd02182b308c96d5bde25a1327 Mon Sep 17 00:00:00 2001
From: Suraj Jitindar Singh <sursingh@redhat.com>
Date: Wed, 6 Dec 2017 02:57:59 +0100
Subject: [PATCH 19/21] ppc: fix setting of compat mode

RH-Author: Suraj Jitindar Singh <sursingh@redhat.com>
Message-id: <1512529079-12590-1-git-send-email-sursingh@redhat.com>
Patchwork-id: 78173
O-Subject: [RHEL7.5 qemu-kvm-rhev PATCH] ppc: fix setting of compat mode
Bugzilla: 1396119
RH-Acked-by: David Gibson <dgibson@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

From: Greg Kurz <groug@kaod.org>

While trying to make KVM PR usable again, commit 5dfaa532ae introduced a
regression: the current compat_pvr value is passed to KVM instead of the
new one. This means that we always pass 0 instead of the max-cpu-compat
PVR during the initial machine reset. And at CAS time, we either pass
the PVR from the command line or even don't call kvmppc_set_compat() at
all, ie, the PCR will not be set as expected.

For example if we start a big endian fedora26 guest in power7 compat
mode on a POWER8 host, we get this in the guest:

$ cat /proc/cpuinfo
processor       : 0
cpu             : POWER7 (architected), altivec supported
clock           : 4024.000000MHz
revision        : 2.0 (pvr 004d 0200)

timebase        : 512000000
platform        : pSeries
model           : IBM pSeries (emulated by qemu)
machine         : CHRP IBM pSeries (emulated by qemu)
MMU             : Hash

but the guest can still execute POWER8 instructions, and the following
program succeeds:

int main()
{
        asm("vncipher 0,0,0"); // ISA 2.07 instruction
}

Let's pass the new compat_pvr to kvmppc_set_compat() and the program fails
with SIGILL as expected.

Reported-by: Nageswara R Sastry <rnsastry@linux.vnet.ibm.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit e4f0c6bb1a9f72ad9e32c3171d36bae17ea1cd67)

Signed-off-by: Suraj Jitindar Singh <sursingh@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 target/ppc/compat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/ppc/compat.c b/target/ppc/compat.c
index 540b4eb..2d95434 100644
--- a/target/ppc/compat.c
+++ b/target/ppc/compat.c
@@ -152,7 +152,7 @@ void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
     cpu_synchronize_state(CPU(cpu));
 
     if (kvm_enabled() && cpu->compat_pvr != compat_pvr) {
-        int ret = kvmppc_set_compat(cpu, cpu->compat_pvr);
+        int ret = kvmppc_set_compat(cpu, compat_pvr);
         if (ret < 0) {
             error_setg_errno(errp, -ret,
                              "Unable to set CPU compatibility mode in KVM");
-- 
1.8.3.1