qom/cpu: move tlb_flush to cpu_common_reset

It is a common thing amongst the various cpu reset functions want to
flush the SoftMMU's TLB entries. This is done either by calling
tlb_flush directly or by way of a general memset of the CPU
structure (sometimes both).

This moves the tlb_flush call to the common reset function and
additionally ensures it is only done for the CONFIG_SOFTMMU case and
when tcg is enabled.

In some target cases we add an empty end_of_reset_fields structure to the
target vCPU structure so have a clear end point for any memset which
is resetting value in the structure before CPU_COMMON (where the TLB
structures are).

While this is a nice clean-up in general it is also a precursor for
changes coming to cputlb for MTTCG where the clearing of entries
can't be done arbitrarily across vCPUs. Currently the cpu_reset
function is usually called from the context of another vCPU as the
architectural power up sequence is run. By using the cputlb API
functions we can ensure the right behaviour in the future.

Backports commit 1f5c00cfdb8114c1e3a13426588ceb64f82c9ddb from qemu

qemu/qom/cpu.c

@@ -175,6 +175,10 @@ static void cpu_common_reset(CPUState *cpu)
     for (i = 0; i < TB_JMP_CACHE_SIZE; ++i) {
         atomic_set(&cpu->tb_jmp_cache[i], NULL);
     }
+
+#ifdef CONFIG_SOFTMMU
+    tlb_flush(cpu, 0);
+#endif
 }
 
 static bool cpu_common_has_work(CPUState *cs)

qemu/target-arm/cpu.c

@@ -118,7 +118,7 @@ static void arm_cpu_reset(CPUState *s)
 
     acc->parent_reset(s);
 
-    memset(env, 0, offsetof(CPUARMState, features));
+    memset(env, 0, offsetof(CPUARMState, end_reset_fields));
     g_hash_table_foreach(cpu->cp_regs, cp_reg_reset, cpu);
     g_hash_table_foreach(cpu->cp_regs, cp_reg_check_reset, cpu);
     env->vfp.xregs[ARM_VFP_FPSID] = cpu->reset_fpsid;
@@ -231,7 +231,6 @@ static void arm_cpu_reset(CPUState *s)
                               &env->vfp.fp_status);
     set_float_detect_tininess(float_tininess_before_rounding,
                               &env->vfp.standard_fp_status);
-    tlb_flush(s, 1);
 
     hw_breakpoint_update_all(cpu);
     hw_watchpoint_update_all(cpu);

qemu/target-arm/cpu.h

@@ -498,9 +498,12 @@ typedef struct CPUARMState {
     struct CPUBreakpoint *cpu_breakpoint[16];
     struct CPUWatchpoint *cpu_watchpoint[16];
 
+    /* Fields up to this point are cleared by a CPU reset */
+    struct {} end_reset_fields;
+
     CPU_COMMON
 
-    /* These fields after the common ones so they are preserved on reset.  */
+    /* Fields after CPU_COMMON are preserved across CPU reset. */
 
     /* Internal CPU feature flags.  */
     uint64_t features;

qemu/target-i386/cpu.c

@@ -2846,8 +2846,6 @@ static void x86_cpu_reset(CPUState *s)
 
     memset(env, 0, offsetof(CPUX86State, end_reset_fields));
 
-    tlb_flush(s, 1);
-
     env->old_exception = -1;
 
     /* init to reset state */

qemu/target-i386/cpu.h

@@ -1108,10 +1108,12 @@ typedef struct CPUX86State {
     uint8_t nmi_injected;
     uint8_t nmi_pending;
 
+    /* Fields up to this point are cleared by a CPU reset */
+    struct {} end_reset_fields;
+
     CPU_COMMON
 
-    /* Fields from here on are preserved across CPU reset. */
-    struct {} end_reset_fields;
+    /* Fields after CPU_COMMON are preserved across CPU reset. */
 
     /* processor features (e.g. for CPUID insn) */
     /* Minimum level/xlevel/xlevel2, based on CPU model + features */

qemu/target-m68k/cpu.c

@@ -52,7 +52,7 @@ static void m68k_cpu_reset(CPUState *s)
 
     mcc->parent_reset(s);
 
-    memset(env, 0, offsetof(CPUM68KState, features));
+    memset(env, 0, offsetof(CPUM68KState, end_reset_fields));
 #if !defined(CONFIG_USER_ONLY)
     env->sr = 0x2700;
 #endif
@@ -61,7 +61,6 @@ static void m68k_cpu_reset(CPUState *s)
     cpu_m68k_set_ccr(env, 0);
     /* TODO: We should set PC from the interrupt vector.  */
     env->pc = 0;
-    tlb_flush(s, 1);
 }
 
 /* CPU models */

qemu/target-m68k/cpu.h

@@ -114,6 +114,9 @@ typedef struct CPUM68KState {
 
     uint32_t qregs[MAX_QREGS];
 
+    /* Fields up to this point are cleared by a CPU reset */
+    struct {} end_reset_fields;
+
     CPU_COMMON
 
     /* Fields from here on are preserved across CPU reset. */

qemu/target-mips/cpu.c

@@ -99,8 +99,7 @@ static void mips_cpu_reset(CPUState *s)
 
     mcc->parent_reset(s);
 
-    memset(env, 0, offsetof(CPUMIPSState, mvp));
-    tlb_flush(s, 1);
+    memset(env, 0, offsetof(CPUMIPSState, end_reset_fields));
 
     cpu_state_reset(env);
 }

qemu/target-mips/cpu.h

@@ -603,6 +603,9 @@ struct CPUMIPSState {
     uint32_t CP0_TCStatus_rw_bitmask; /* Read/write bits in CP0_TCStatus */
     int insn_flags; /* Supported instruction set */
 
+    /* Fields up to this point are cleared by a CPU reset */
+    struct {} end_reset_fields;
+
     CPU_COMMON
 
     /* Fields from here on are preserved across CPU reset. */

qemu/target-sparc/cpu.c

@@ -36,8 +36,7 @@ static void sparc_cpu_reset(CPUState *s)
 
     scc->parent_reset(s);
 
-    memset(env, 0, offsetof(CPUSPARCState, version));
-    tlb_flush(s, 1);
+    memset(env, 0, offsetof(CPUSPARCState, end_reset_fields));
     env->cwp = 0;
 #ifndef TARGET_SPARC64
     env->wim = 1;

qemu/target-sparc/cpu.h

@@ -413,6 +413,9 @@ struct CPUSPARCState {
     /* NOTE: we allow 8 more registers to handle wrapping */
     target_ulong regbase[MAX_NWINDOWS * 16 + 8];
 
+    /* Fields up to this point are cleared by a CPU reset */
+    struct {} end_reset_fields;
+
     CPU_COMMON
 
     /* Fields from here on are preserved across CPU reset. */