Merge tag 'pull-ppc-20220728' of https://gitlab.com/danielhb/qemu into staging

ppc patch queue for 2022-07-28:

Short queue with 2 Coverity fixes and one fix of the
'wait' insns that is causing hangs if the guest kernel uses
the most up to date wait opcode.

- target/ppc:
  - implement new wait variants to fix guest hang when using the new opcode
- ppc440_uc: initialize length passed to cpu_physical_memory_map()
- spapr_nvdimm: check if spapr_drc_index() returns NULL

# -----BEGIN PGP SIGNATURE-----
#
# iHUEABYKAB0WIQQX6/+ZI9AYAK8oOBk82cqW3gMxZAUCYuK8VgAKCRA82cqW3gMx
# ZOc7AQDPMsFY9NHNqJ3O0MiX4Qoy8IGUreZ9dzZSS3zT1nxtEAD+Lwl0/aGO+dk+
# +NiIO80A5Agy/0g8PHie4qR3EqHEnwA=
# =Q4eR
# -----END PGP SIGNATURE-----
# gpg: Signature made Thu 28 Jul 2022 09:41:58 AM PDT
# gpg:                using EDDSA key 17EBFF9923D01800AF2838193CD9CA96DE033164
# gpg: Good signature from "Daniel Henrique Barboza <danielhb413@gmail.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 17EB FF99 23D0 1800 AF28  3819 3CD9 CA96 DE03 3164

* tag 'pull-ppc-20220728' of https://gitlab.com/danielhb/qemu:
  target/ppc: Implement new wait variants
  hw/ppc/ppc440_uc: Initialize length passed to cpu_physical_memory_map()
  hw/ppc: check if spapr_drc_index() returns NULL in spapr_nvdimm.c

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

2 files changed, 91 insertions, 8 deletions

diff --git a/target/ppc/internal.h b/target/ppc/internal.h
index 467f304..337a362 100644
--- a/target/ppc/internal.h
+++ b/target/ppc/internal.h
@@ -165,6 +165,9 @@ EXTRACT_HELPER_SPLIT_3(DX, 10, 6, 6, 5, 16, 1, 1, 0, 0)
 /* darn */
 EXTRACT_HELPER(L, 16, 2);
 #endif
+/* wait */
+EXTRACT_HELPER(WC, 21, 2);
+EXTRACT_HELPER(PL, 16, 2);
 
 /***                            Jump target decoding                       ***/
 /* Immediate address */
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 5a18ee5..388337f 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -4071,12 +4071,91 @@ static void gen_sync(DisasContext *ctx)
 /* wait */
 static void gen_wait(DisasContext *ctx)
 {
-    TCGv_i32 t0 = tcg_const_i32(1);
-    tcg_gen_st_i32(t0, cpu_env,
-                   -offsetof(PowerPCCPU, env) + offsetof(CPUState, halted));
-    tcg_temp_free_i32(t0);
-    /* Stop translation, as the CPU is supposed to sleep from now */
-    gen_exception_nip(ctx, EXCP_HLT, ctx->base.pc_next);
+    uint32_t wc;
+
+    if (ctx->insns_flags & PPC_WAIT) {
+        /* v2.03-v2.07 define an older incompatible 'wait' encoding. */
+
+        if (ctx->insns_flags2 & PPC2_PM_ISA206) {
+            /* v2.06 introduced the WC field. WC > 0 may be treated as no-op. */
+            wc = WC(ctx->opcode);
+        } else {
+            wc = 0;
+        }
+
+    } else if (ctx->insns_flags2 & PPC2_ISA300) {
+        /* v3.0 defines a new 'wait' encoding. */
+        wc = WC(ctx->opcode);
+        if (ctx->insns_flags2 & PPC2_ISA310) {
+            uint32_t pl = PL(ctx->opcode);
+
+            /* WC 1,2 may be treated as no-op. WC 3 is reserved. */
+            if (wc == 3) {
+                gen_invalid(ctx);
+                return;
+            }
+
+            /* PL 1-3 are reserved. If WC=2 then the insn is treated as noop. */
+            if (pl > 0 && wc != 2) {
+                gen_invalid(ctx);
+                return;
+            }
+
+        } else { /* ISA300 */
+            /* WC 1-3 are reserved */
+            if (wc > 0) {
+                gen_invalid(ctx);
+                return;
+            }
+        }
+
+    } else {
+        warn_report("wait instruction decoded with wrong ISA flags.");
+        gen_invalid(ctx);
+        return;
+    }
+
+    /*
+     * wait without WC field or with WC=0 waits for an exception / interrupt
+     * to occur.
+     */
+    if (wc == 0) {
+        TCGv_i32 t0 = tcg_const_i32(1);
+        tcg_gen_st_i32(t0, cpu_env,
+                       -offsetof(PowerPCCPU, env) + offsetof(CPUState, halted));
+        tcg_temp_free_i32(t0);
+        /* Stop translation, as the CPU is supposed to sleep from now */
+        gen_exception_nip(ctx, EXCP_HLT, ctx->base.pc_next);
+    }
+
+    /*
+     * Other wait types must not just wait until an exception occurs because
+     * ignoring their other wake-up conditions could cause a hang.
+     *
+     * For v2.06 and 2.07, wc=1,2,3 are architected but may be implemented as
+     * no-ops.
+     *
+     * wc=1 and wc=3 explicitly allow the instruction to be treated as a no-op.
+     *
+     * wc=2 waits for an implementation-specific condition, such could be
+     * always true, so it can be implemented as a no-op.
+     *
+     * For v3.1, wc=1,2 are architected but may be implemented as no-ops.
+     *
+     * wc=1 (waitrsv) waits for an exception or a reservation to be lost.
+     * Reservation-loss may have implementation-specific conditions, so it
+     * can be implemented as a no-op.
+     *
+     * wc=2 waits for an exception or an amount of time to pass. This
+     * amount is implementation-specific so it can be implemented as a
+     * no-op.
+     *
+     * ISA v3.1 allows for execution to resume "in the rare case of
+     * an implementation-dependent event", so in any case software must
+     * not depend on the architected resumption condition to become
+     * true, so no-op implementations should be architecturally correct
+     * (if suboptimal).
+     */
 }
 
 #if defined(TARGET_PPC64)
@@ -6691,8 +6770,9 @@ GEN_HANDLER2(stdcx_, "stdcx.", 0x1F, 0x16, 0x06, 0x00000000, PPC_64B),
 GEN_HANDLER_E(stqcx_, 0x1F, 0x16, 0x05, 0, PPC_NONE, PPC2_LSQ_ISA207),
 #endif
 GEN_HANDLER(sync, 0x1F, 0x16, 0x12, 0x039FF801, PPC_MEM_SYNC),
-GEN_HANDLER(wait, 0x1F, 0x1E, 0x01, 0x03FFF801, PPC_WAIT),
-GEN_HANDLER_E(wait, 0x1F, 0x1E, 0x00, 0x039FF801, PPC_NONE, PPC2_ISA300),
+/* ISA v3.0 changed the extended opcode from 62 to 30 */
+GEN_HANDLER(wait, 0x1F, 0x1E, 0x01, 0x039FF801, PPC_WAIT),
+GEN_HANDLER_E(wait, 0x1F, 0x1E, 0x00, 0x039CF801, PPC_NONE, PPC2_ISA300),
 GEN_HANDLER(b, 0x12, 0xFF, 0xFF, 0x00000000, PPC_FLOW),
 GEN_HANDLER(bc, 0x10, 0xFF, 0xFF, 0x00000000, PPC_FLOW),
 GEN_HANDLER(bcctr, 0x13, 0x10, 0x10, 0x00000000, PPC_FLOW),