target/i386: implement RDPID in TCG

RDPID corresponds to a RDMSR(TSC_AUX); however, it is unprivileged
so for user-mode emulation we must provide the value that the kernel
places in the MSR.  For Linux, it is a combination of the current CPU
and the current NUMA node, both of which can be retrieved with getcpu(2).
Also try sched_getcpu(), which might be there on the BSDs.  If there is
no portable way to retrieve the current CPU id from userspace, return 0.

RDTSCP is reimplemented as RDTSC + RDPID ECX; the differences in terms
of serializability are not relevant to QEMU.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -2232,6 +2232,8 @@ config_host_data.set('CONFIG_CLOCK_ADJTIME', cc.has_function('clock_adjtime'))
 config_host_data.set('CONFIG_DUP3', cc.has_function('dup3'))
 config_host_data.set('CONFIG_FALLOCATE', cc.has_function('fallocate'))
 config_host_data.set('CONFIG_POSIX_FALLOCATE', cc.has_function('posix_fallocate'))
+config_host_data.set('CONFIG_GETCPU', cc.has_function('getcpu', prefix: gnu_source_prefix))
+config_host_data.set('CONFIG_SCHED_GETCPU', cc.has_function('sched_getcpu', prefix: '#include <sched.h>'))
 # Note that we need to specify prefix: here to avoid incorrectly
 # thinking that Windows has posix_memalign()
 config_host_data.set('CONFIG_POSIX_MEMALIGN', cc.has_function('posix_memalign', prefix: '#include <stdlib.h>'))

target/i386/cpu.c

@@ -661,9 +661,17 @@ void x86_cpu_vendor_words2str(char *dst, uint32_t vendor1,
           /* missing:
           CPUID_7_0_EBX_HLE
           CPUID_7_0_EBX_INVPCID, CPUID_7_0_EBX_RTM */
+
+#if defined CONFIG_SOFTMMU || defined CONFIG_LINUX
+#define TCG_7_0_ECX_RDPID CPUID_7_0_ECX_RDPID
+#else
+#define TCG_7_0_ECX_RDPID 0
+#endif
 #define TCG_7_0_ECX_FEATURES (CPUID_7_0_ECX_UMIP | CPUID_7_0_ECX_PKU | \
           /* CPUID_7_0_ECX_OSPKE is dynamic */ \
-          CPUID_7_0_ECX_LA57 | CPUID_7_0_ECX_PKS | CPUID_7_0_ECX_VAES)
+          CPUID_7_0_ECX_LA57 | CPUID_7_0_ECX_PKS | CPUID_7_0_ECX_VAES | \
+          TCG_7_0_ECX_RDPID)
+
 #define TCG_7_0_EDX_FEATURES CPUID_7_0_EDX_FSRM
 #define TCG_7_1_EAX_FEATURES (CPUID_7_1_EAX_FZRM | CPUID_7_1_EAX_FSRS | \
           CPUID_7_1_EAX_FSRC)

target/i386/helper.h

@@ -69,8 +69,8 @@ DEF_HELPER_2(into, void, env, int)
 DEF_HELPER_FLAGS_1(single_step, TCG_CALL_NO_WG, noreturn, env)
 DEF_HELPER_1(rechecking_single_step, void, env)
 DEF_HELPER_1(cpuid, void, env)
+DEF_HELPER_FLAGS_1(rdpid, TCG_CALL_NO_WG, tl, env)
 DEF_HELPER_1(rdtsc, void, env)
-DEF_HELPER_1(rdtscp, void, env)
 DEF_HELPER_FLAGS_1(rdpmc, TCG_CALL_NO_WG, noreturn, env)
 
 #ifndef CONFIG_USER_ONLY

target/i386/tcg/misc_helper.c

@@ -75,12 +75,6 @@ void helper_rdtsc(CPUX86State *env)
     env->regs[R_EDX] = (uint32_t)(val >> 32);
 }
 
-void helper_rdtscp(CPUX86State *env)
-{
-    helper_rdtsc(env);
-    env->regs[R_ECX] = (uint32_t)(env->tsc_aux);
-}
-
 G_NORETURN void helper_rdpmc(CPUX86State *env)
 {
     if (((env->cr[4] & CR4_PCE_MASK) == 0 ) &&
@@ -137,3 +131,18 @@ void helper_wrpkru(CPUX86State *env, uint32_t ecx, uint64_t val)
     env->pkru = val;
     tlb_flush(cs);
 }
+
+target_ulong HELPER(rdpid)(CPUX86State *env)
+{
+#if defined CONFIG_SOFTMMU
+    return env->tsc_aux;
+#elif defined CONFIG_LINUX && defined CONFIG_GETCPU
+    unsigned cpu, node;
+    getcpu(&cpu, &node);
+    return (node << 12) | (cpu & 0xfff);
+#elif defined CONFIG_SCHED_GETCPU
+    return sched_getcpu();
+#else
+    return 0;
+#endif
+}

target/i386/tcg/translate.c

@@ -3924,13 +3924,25 @@ static bool disas_insn(DisasContext *s, CPUState *cpu)
             gen_cmpxchg8b(s, env, modrm);
             break;
 
-        case 7: /* RDSEED */
+        case 7: /* RDSEED, RDPID with f3 prefix */
             if (mod != 3 ||
-                (s->prefix & (PREFIX_LOCK | PREFIX_REPZ | PREFIX_REPNZ)) ||
-                !(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_RDSEED)) {
+                (s->prefix & (PREFIX_LOCK | PREFIX_REPNZ))) {
                 goto illegal_op;
             }
-            goto do_rdrand;
+            if (s->prefix & PREFIX_REPZ) {
+                if (!(s->cpuid_ext_features & CPUID_7_0_ECX_RDPID)) {
+                    goto illegal_op;
+                }
+                gen_helper_rdpid(s->T0, cpu_env);
+                rm = (modrm & 7) | REX_B(s);
+                gen_op_mov_reg_v(s, dflag, rm, s->T0);
+                break;
+            } else {
+                if (!(s->cpuid_7_0_ebx_features & CPUID_7_0_EBX_RDSEED)) {
+                    goto illegal_op;
+                }
+                goto do_rdrand;
+            }
 
         case 6: /* RDRAND */
             if (mod != 3 ||
@@ -6125,7 +6137,9 @@ static bool disas_insn(DisasContext *s, CPUState *cpu)
             gen_update_cc_op(s);
             gen_update_eip_cur(s);
             translator_io_start(&s->base);
-            gen_helper_rdtscp(cpu_env);
+            gen_helper_rdtsc(cpu_env);
+            gen_helper_rdpid(s->T0, cpu_env);
+            gen_op_mov_reg_v(s, dflag, R_ECX, s->T0);
             break;
 
         default: