From: Nicholas Piggin <npiggin@gmail.com>
Date: Tue, 13 Jun 2023 14:16:23 +0000 (+1000)
Subject: target/ppc: Prevent supervisor from modifying MSR[ME]
X-Git-Tag: v9.0.0-rc0~10^2~36
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=678b6f1af75ef42f510495a81fe8562e872e9daf;p=thirdparty%2Fqemu.git

target/ppc: Prevent supervisor from modifying MSR[ME]

Prevent guest state modifying the MSR[ME] bit. Per ISA:

  An attempt to modify MSR[ME] in privileged but non-hypervisor state
  is ignored (i.e., the bit is not changed).

Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---

diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
index 410b39c231b..25258986e36 100644
--- a/target/ppc/helper_regs.c
+++ b/target/ppc/helper_regs.c
@@ -264,6 +264,11 @@ int hreg_store_msr(CPUPPCState *env, target_ulong value, int alter_hv)
         value &= ~MSR_HVB;
         value |= env->msr & MSR_HVB;
     }
+    /* Attempt to modify MSR[ME] in guest state is ignored */
+    if (is_book3s_arch2x(env) && !(env->msr & MSR_HVB)) {
+        value &= ~(1 << MSR_ME);
+        value |= env->msr & (1 << MSR_ME);
+    }
     if ((value ^ env->msr) & (R_MSR_IR_MASK | R_MSR_DR_MASK)) {
         cpu_interrupt_exittb(cs);
     }