[Qemu-devel] [PATCH 2/3] ppc: Better figure out if processor has HV mode

["Cédric Le Goater" <clg@kaod.org>]

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We use an env. flag which is set to the initial value of MSR_HVB in
the msr_mask. We also adjust the POWER8 mask to set SHV.

Also use this to adjust ctx.hv so that it is *set* when the processor
doesn't have an HV mode (970 with Apple mode for example), thus enabling
hypervisor instructions/SPRs.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
[clg: ctx.hv used to be defined only for the hypervisor kernel
      (HV=1|PR=0). It is now defined also when PR=1 and conditions are
      fixed accordingly.
      stripped unwanted tabs.]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 target-ppc/cpu.h            |  4 ++++
 target-ppc/translate.c      |  4 +++-
 target-ppc/translate_init.c | 19 +++++++++++++++----
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 98a24a50f3b5..d8f8f7e233c7 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -1050,6 +1050,10 @@ struct CPUPPCState {
     hwaddr mpic_iack;
     /* true when the external proxy facility mode is enabled */
     bool mpic_proxy;
+    /* set when the processor has an HV mode, thus HV priv
+     * instructions and SPRs are diallowed if MSR:HV is 0
+     */
+    bool has_hv_mode;
 #endif
 
     /* Those resources are used only during code translation */
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index fe10bf8774cb..ad262523abca 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -11478,8 +11478,10 @@ void gen_intermediate_code(CPUPPCState *env, struct TranslationBlock *tb)
     ctx.exception = POWERPC_EXCP_NONE;
     ctx.spr_cb = env->spr_cb;
     ctx.pr = msr_pr;
-    ctx.hv = !msr_pr && msr_hv;
     ctx.mem_idx = env->dmmu_idx;
+#if !defined(CONFIG_USER_ONLY)
+    ctx.hv = msr_hv || !env->has_hv_mode;
+#endif
     ctx.insns_flags = env->insns_flags;
     ctx.insns_flags2 = env->insns_flags2;
     ctx.access_type = -1;
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index 83010768ea05..55f855309806 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -8450,6 +8450,7 @@ POWERPC_FAMILY(POWER8)(ObjectClass *oc, void *data)
                         PPC2_ISA205 | PPC2_ISA207S | PPC2_FP_CVT_S64 |
                         PPC2_TM;
     pcc->msr_mask = (1ull << MSR_SF) |
+                    (1ull << MSR_SHV) |
                     (1ull << MSR_TM) |
                     (1ull << MSR_VR) |
                     (1ull << MSR_VSX) |
@@ -9854,10 +9855,7 @@ static void ppc_cpu_reset(CPUState *s)
     pcc->parent_reset(s);
 
     msr = (target_ulong)0;
-    if (0) {
-        /* XXX: find a suitable condition to enable the hypervisor mode */
-        msr |= (target_ulong)MSR_HVB;
-    }
+    msr |= (target_ulong)MSR_HVB;
     msr |= (target_ulong)0 << MSR_AP; /* TO BE CHECKED */
     msr |= (target_ulong)0 << MSR_SA; /* TO BE CHECKED */
     msr |= (target_ulong)1 << MSR_EP;
@@ -9958,6 +9956,19 @@ static void ppc_cpu_initfn(Object *obj)
     env->bfd_mach = pcc->bfd_mach;
     env->check_pow = pcc->check_pow;
 
+    /* Mark HV mode as supported if the CPU has an MSR_HV bit
+     * in the msr_mask. The mask can later be cleared by PAPR
+     * mode but the hv mode support will remain, thus enforcing
+     * that we cannot use priv. instructions in guest in PAPR
+     * mode. For 970 we currently simply don't set HV in msr_mask
+     * thus simulating an "Apple mode" 970. If we ever want to
+     * support 970 HV mode, we'll have to add a processor attribute
+     * of some sort.
+     */
+#if !defined(CONFIG_USER_ONLY)
+    env->has_hv_mode = !!(env->msr_mask & MSR_HVB);
+#endif
+
 #if defined(TARGET_PPC64)
     if (pcc->sps) {
         env->sps = *pcc->sps;
-- 
2.1.4