[RFC PATCH 2/2] target/ppc: Add POWER10 exception model

[Nicholas Piggin <npiggin@gmail.com>]

POWER10 adds a new bit that modifies interrupt behaviour, LPCR[HAIL],
and it removes support for the LPCR[AIL]=0b10 mode.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/ppc/spapr_hcall.c            |  7 +++++-
 target/ppc/cpu-qom.h            |  2 ++
 target/ppc/cpu.h                |  5 ++--
 target/ppc/excp_helper.c        | 43 +++++++++++++++++++++++++++++++++
 target/ppc/translate.c          |  3 ++-
 target/ppc/translate_init.c.inc |  2 +-
 6 files changed, 57 insertions(+), 5 deletions(-)

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 2fbe04a689..6802cd4dc8 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1396,7 +1396,12 @@ static target_ulong h_set_mode_resource_addr_trans_mode(PowerPCCPU *cpu,
     }
 
     if (mflags == 1) {
-        /* AIL=1 is reserved */
+        /* AIL=1 is reserved in POWER8/POWER9 */
+        return H_UNSUPPORTED_FLAG;
+    }
+
+    if (mflags == 2 && (pcc->insns_flags2 & PPC2_ISA310)) {
+        /* AIL=2 is also reserved in POWER10 (ISA v3.1) */
         return H_UNSUPPORTED_FLAG;
     }
 
diff --git a/target/ppc/cpu-qom.h b/target/ppc/cpu-qom.h
index 118baf8d41..06b6571bc9 100644
--- a/target/ppc/cpu-qom.h
+++ b/target/ppc/cpu-qom.h
@@ -116,6 +116,8 @@ enum powerpc_excp_t {
     POWERPC_EXCP_POWER8,
     /* POWER9 exception model           */
     POWERPC_EXCP_POWER9,
+    /* POWER10 exception model           */
+    POWERPC_EXCP_POWER10,
 };
 
 /*****************************************************************************/
diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 5200a16d23..9d35cdfa92 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -354,10 +354,11 @@ typedef struct ppc_v3_pate_t {
 #define LPCR_PECE_U_SHIFT (63 - 19)
 #define LPCR_PECE_U_MASK  (0x7ull << LPCR_PECE_U_SHIFT)
 #define LPCR_HVEE         PPC_BIT(17) /* Hypervisor Virt Exit Enable */
-#define LPCR_RMLS_SHIFT   (63 - 37)
+#define LPCR_RMLS_SHIFT   (63 - 37)   /* RMLS (removed in ISA v3.0) */
 #define LPCR_RMLS         (0xfull << LPCR_RMLS_SHIFT)
+#define LPCR_HAIL         PPC_BIT(37) /* ISA v3.1 HV AIL=3 equivalent */
 #define LPCR_ILE          PPC_BIT(38)
-#define LPCR_AIL_SHIFT    (63 - 40)      /* Alternate interrupt location */
+#define LPCR_AIL_SHIFT    (63 - 40)   /* Alternate interrupt location */
 #define LPCR_AIL          (3ull << LPCR_AIL_SHIFT)
 #define LPCR_UPRT         PPC_BIT(41) /* Use Process Table */
 #define LPCR_EVIRT        PPC_BIT(42) /* Enhanced Virtualisation */
diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index 9ff316767c..19931361a0 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -172,6 +172,26 @@ static int powerpc_reset_wakeup(CPUState *cs, CPUPPCState *env, int excp,
  *
  * The difference with POWER9 being that MSR[HV] 0->1 interrupts can be
  * sent to the hypervisor in AIL mode if the guest is radix (LPCR[HR]=1).
+ * This is good for performance but allows the guest to influence the
+ * AIL of hypervisor interrupts using its MSR, and also the hypervisor
+ * must disallow guest interrupts (MSR[HV] 0->0) from using AIL if the
+ * hypervisor does not want to use AIL for its MSR[HV] 0->1 interrupts.
+ *
+ * POWER10 addresses those issues with a new LPCR[HAIL] bit that is
+ * applied to interrupt that begin execution with MSR[HV]=1 (so both
+ * MSR[HV] 0->1 and 1->1).
+ *
+ * HAIL=1 is equivalent to AIL=3, for interrupts delivered with MSR[HV]=1.
+ *
+ * POWER10 behaviour is
+ * | LPCR[AIL] | LPCR[HAIL] | MSR[IR||DR] | MSR[HV] | new MSR[HV] | AIL |
+ * +-----------+------------+-------------+---------+-------------+-----+
+ * | a         | h          | 00/01/10    | 0       | 0           | 0   |
+ * | a         | h          | 11          | 0       | 0           | a   |
+ * | a         | h          | x           | 0       | 1           | h   |
+ * | a         | h          | 00/01/10    | 1       | 1           | 0   |
+ * | a         | h          | 11          | 1       | 1           | h   |
+ * +--------------------------------------------------------------------+
  */
 static inline void ppc_excp_apply_ail(PowerPCCPU *cpu, int excp_model, int excp,
                                       target_ulong msr,
@@ -211,6 +231,29 @@ static inline void ppc_excp_apply_ail(PowerPCCPU *cpu, int excp_model, int excp,
             /* AIL=1 is reserved */
             return;
         }
+
+    } else if (excp_model == POWERPC_EXCP_POWER10) {
+        if (!mmu_all_on && !hv_escalation) {
+            /*
+             * AIL works for HV interrupts even with guest MSR[IR/DR] disabled.
+             * Guest->guest and HV->HV interrupts do require MMU on.
+             */
+            return;
+        }
+
+        if (*new_msr & MSR_HVB) {
+            if (!(env->spr[SPR_LPCR] & LPCR_HAIL)) {
+                /* HV interrupts depend on LPCR[HAIL] */
+                return;
+            }
+            ail = 3; /* HAIL=1 gives AIL=3 behaviour for HV interrupts */
+        } else {
+            ail = (env->spr[SPR_LPCR] & LPCR_AIL) >> LPCR_AIL_SHIFT;
+        }
+        if (ail != 3) {
+            /* AIL=1 and AIL=2 are reserved */
+            return;
+        }
     } else {
         /* Other processors do not support AIL */
         return;
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 0984ce637b..e9ed001229 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -7731,7 +7731,8 @@ void ppc_cpu_dump_state(CPUState *cs, FILE *f, int flags)
 #if defined(TARGET_PPC64)
     if (env->excp_model == POWERPC_EXCP_POWER7 ||
         env->excp_model == POWERPC_EXCP_POWER8 ||
-        env->excp_model == POWERPC_EXCP_POWER9)  {
+        env->excp_model == POWERPC_EXCP_POWER9 ||
+        env->excp_model == POWERPC_EXCP_POWER10)  {
         qemu_fprintf(f, "HSRR0 " TARGET_FMT_lx " HSRR1 " TARGET_FMT_lx "\n",
                      env->spr[SPR_HSRR0], env->spr[SPR_HSRR1]);
     }
diff --git a/target/ppc/translate_init.c.inc b/target/ppc/translate_init.c.inc
index a82d9ed647..76d82cc2f6 100644
--- a/target/ppc/translate_init.c.inc
+++ b/target/ppc/translate_init.c.inc
@@ -9317,7 +9317,7 @@ POWERPC_FAMILY(POWER10)(ObjectClass *oc, void *data)
     pcc->radix_page_info = &POWER10_radix_page_info;
     pcc->lrg_decr_bits = 56;
 #endif
-    pcc->excp_model = POWERPC_EXCP_POWER9;
+    pcc->excp_model = POWERPC_EXCP_POWER10;
     pcc->bus_model = PPC_FLAGS_INPUT_POWER9;
     pcc->bfd_mach = bfd_mach_ppc64;
     pcc->flags = POWERPC_FLAG_VRE | POWERPC_FLAG_SE |
-- 
2.23.0