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From 45af32e160bf339974a74bb8a38384b95aa2f555 Mon Sep 17 00:00:00 2001
From: David Gibson <david@gibson.dropbear.id.au>
Date: Tue, 25 Sep 2012 17:12:20 +0000
Subject: [PATCH] pseries: Don't test for MSR_PR for hypercalls under KVM

PAPR hypercalls should only be invoked from the guest kernel, not guest
user programs, that is, with MSR[PR]=0.  Currently we check this in
spapr_hypercall, returning H_PRIVILEGE if MSR[PR]=1.

However, under KVM the state of MSR[PR] is already checked by the host
kernel before passing the hypercall to qemu, making this check redundant.
Worse, however, we don't generally synchronize KVM and qemu state on the
hypercall path, meaning that qemu could incorrectly reject a hypercall
because it has a stale MSR value.

This patch fixes the problem by moving the privilege test exclusively to
the TCG hypercall path.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
CC: qemu-stable@nongnu.org
Signed-off-by: Alexander Graf <agraf@suse.de>
(cherry picked from commit efcb9383b974114e5f682e531346006f8f2466c0)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hw/spapr.c       | 7 ++++++-
 hw/spapr_hcall.c | 5 -----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/hw/spapr.c b/hw/spapr.c
index c34b767..5e55430 100644
--- a/hw/spapr.c
+++ b/hw/spapr.c
@@ -556,7 +556,12 @@ static uint64_t translate_kernel_address(void *opaque, uint64_t addr)
 
 static void emulate_spapr_hypercall(CPUPPCState *env)
 {
-    env->gpr[3] = spapr_hypercall(env, env->gpr[3], &env->gpr[4]);
+    if (msr_pr) {
+        hcall_dprintf("Hypercall made with MSR[PR]=1\n");
+        env->gpr[3] = H_PRIVILEGE;
+    } else {
+        env->gpr[3] = spapr_hypercall(env, env->gpr[3], &env->gpr[4]);
+    }
 }
 
 static void spapr_reset(void *opaque)
diff --git a/hw/spapr_hcall.c b/hw/spapr_hcall.c
index abd847f..38098f7 100644
--- a/hw/spapr_hcall.c
+++ b/hw/spapr_hcall.c
@@ -713,11 +713,6 @@ void spapr_register_hypercall(target_ulong opcode, spapr_hcall_fn fn)
 target_ulong spapr_hypercall(CPUPPCState *env, target_ulong opcode,
                              target_ulong *args)
 {
-    if (msr_pr) {
-        hcall_dprintf("Hypercall made with MSR[PR]=1\n");
-        return H_PRIVILEGE;
-    }
-
     if ((opcode <= MAX_HCALL_OPCODE)
         && ((opcode & 0x3) == 0)) {
         spapr_hcall_fn fn = papr_hypercall_table[opcode / 4];