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accel/tcg: Always require can_do_io, for #1866 

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Merge tag 'pull-tcg-20230928' of https://gitlab.com/rth7680/qemu into staging

accel/tcg: Always require can_do_io, for #1866

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* tag 'pull-tcg-20230928' of https://gitlab.com/rth7680/qemu:
  accel/tcg: Always require can_do_io
  accel/tcg: Always set CF_LAST_IO with CF_NOIRQ
  accel/tcg: Improve setting of can_do_io at start of TB
  accel/tcg: Track current value of can_do_io in the TB
  accel/tcg: Hoist CF_MEMI_ONLY check outside translation loop
  accel/tcg: Avoid load of icount_decr if unused

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2023-10-02 14:42:05 -04:00
parent 5436f1b1c3 18a536f1f8
commit 5b0d1a8395
5 changed files with 41 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
accel/tcg/cpu-exec.c
View File

@ -720,7 +720,7 @@ static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
&& cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0) {
/* Execute just one insn to trigger exception pending in the log */
cpu->cflags_next_tb = (curr_cflags(cpu) & ~CF_USE_ICOUNT)
| CF_NOIRQ | 1;
| CF_LAST_IO | CF_NOIRQ | 1;
}
#endif
return false;

6
accel/tcg/tb-maint.c
View File

@ -1083,7 +1083,8 @@ bool tb_invalidate_phys_page_unwind(tb_page_addr_t addr, uintptr_t pc)
if (current_tb_modified) {
/* Force execution of one insn next time. */
CPUState *cpu = current_cpu;
cpu->cflags_next_tb = 1 | CF_NOIRQ | curr_cflags(current_cpu);
cpu->cflags_next_tb =
1 | CF_LAST_IO | CF_NOIRQ | curr_cflags(current_cpu);
return true;
}
return false;
@ -1153,7 +1154,8 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages,
if (current_tb_modified) {
page_collection_unlock(pages);
/* Force execution of one insn next time. */
current_cpu->cflags_next_tb = 1 | CF_NOIRQ | curr_cflags(current_cpu);
current_cpu->cflags_next_tb =
1 | CF_LAST_IO | CF_NOIRQ | curr_cflags(current_cpu);
mmap_unlock();
cpu_loop_exit_noexc(current_cpu);
}

72
accel/tcg/translator.c
View File

@ -16,26 +16,19 @@
#include "tcg/tcg-op-common.h"
#include "internal.h"
static void gen_io_start(void)
static void set_can_do_io(DisasContextBase *db, bool val)
{
tcg_gen_st_i32(tcg_constant_i32(1), cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
if (db->saved_can_do_io != val) {
db->saved_can_do_io = val;
tcg_gen_st_i32(tcg_constant_i32(val), cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
}
}
bool translator_io_start(DisasContextBase *db)
{
uint32_t cflags = tb_cflags(db->tb);
if (!(cflags & CF_USE_ICOUNT)) {
return false;
}
if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
/* Already started in translator_loop. */
return true;
}
gen_io_start();
set_can_do_io(db, true);
/*
* Ensure that this instruction will be the last in the TB.
@ -47,14 +40,17 @@ bool translator_io_start(DisasContextBase *db)
return true;
}
static TCGOp *gen_tb_start(uint32_t cflags)
static TCGOp *gen_tb_start(DisasContextBase *db, uint32_t cflags)
{
TCGv_i32 count = tcg_temp_new_i32();
TCGv_i32 count = NULL;
TCGOp *icount_start_insn = NULL;
tcg_gen_ld_i32(count, cpu_env,
offsetof(ArchCPU, neg.icount_decr.u32) -
offsetof(ArchCPU, env));
if ((cflags & CF_USE_ICOUNT) || !(cflags & CF_NOIRQ)) {
count = tcg_temp_new_i32();
tcg_gen_ld_i32(count, cpu_env,
offsetof(ArchCPU, neg.icount_decr.u32) -
offsetof(ArchCPU, env));
}
if (cflags & CF_USE_ICOUNT) {
/*
@ -84,18 +80,15 @@ static TCGOp *gen_tb_start(uint32_t cflags)
tcg_gen_st16_i32(count, cpu_env,
offsetof(ArchCPU, neg.icount_decr.u16.low) -
offsetof(ArchCPU, env));
/*
* cpu->can_do_io is cleared automatically here at the beginning of
* each translation block. The cost is minimal and only paid for
* -icount, plus it would be very easy to forget doing it in the
* translator. Doing it here means we don't need a gen_io_end() to
* go with gen_io_start().
*/
tcg_gen_st_i32(tcg_constant_i32(0), cpu_env,
offsetof(ArchCPU, parent_obj.can_do_io) -
offsetof(ArchCPU, env));
}
/*
* cpu->can_do_io is set automatically here at the beginning of
* each translation block. The cost is minimal, plus it would be
* very easy to forget doing it in the translator.
*/
set_can_do_io(db, db->max_insns == 1 && (cflags & CF_LAST_IO));
return icount_start_insn;
}
@ -144,6 +137,7 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
db->num_insns = 0;
db->max_insns = *max_insns;
db->singlestep_enabled = cflags & CF_SINGLE_STEP;
db->saved_can_do_io = -1;
db->host_addr[0] = host_pc;
db->host_addr[1] = NULL;
@ -151,11 +145,17 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
/* Start translating. */
icount_start_insn = gen_tb_start(cflags);
icount_start_insn = gen_tb_start(db, cflags);
ops->tb_start(db, cpu);
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
plugin_enabled = plugin_gen_tb_start(cpu, db, cflags & CF_MEMI_ONLY);
if (cflags & CF_MEMI_ONLY) {
/* We should only see CF_MEMI_ONLY for io_recompile. */
assert(cflags & CF_LAST_IO);
plugin_enabled = plugin_gen_tb_start(cpu, db, true);
} else {
plugin_enabled = plugin_gen_tb_start(cpu, db, false);
}
while (true) {
*max_insns = ++db->num_insns;
@ -172,13 +172,9 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int *max_insns,
the next instruction. */
if (db->num_insns == db->max_insns && (cflags & CF_LAST_IO)) {
/* Accept I/O on the last instruction. */
gen_io_start();
ops->translate_insn(db, cpu);
} else {
/* we should only see CF_MEMI_ONLY for io_recompile */
tcg_debug_assert(!(cflags & CF_MEMI_ONLY));
ops->translate_insn(db, cpu);
set_can_do_io(db, true);
}
ops->translate_insn(db, cpu);
/*
* We can't instrument after instructions that change control

2
include/exec/translator.h
View File

@ -72,6 +72,7 @@ typedef enum DisasJumpType {
* @num_insns: Number of translated instructions (including current).
* @max_insns: Maximum number of instructions to be translated in this TB.
* @singlestep_enabled: "Hardware" single stepping enabled.
* @saved_can_do_io: Known value of cpu->neg.can_do_io, or -1 for unknown.
*
* Architecture-agnostic disassembly context.
*/
@ -83,6 +84,7 @@ typedef struct DisasContextBase {
int num_insns;
int max_insns;
bool singlestep_enabled;
int8_t saved_can_do_io;
void *host_addr[2];
} DisasContextBase;

1
target/mips/tcg/translate.c
View File

@ -11212,7 +11212,6 @@ static void gen_branch(DisasContext *ctx, int insn_bytes)
/* Branches completion */
clear_branch_hflags(ctx);
ctx->base.is_jmp = DISAS_NORETURN;
/* FIXME: Need to clear can_do_io. */
switch (proc_hflags & MIPS_HFLAG_BMASK_BASE) {
case MIPS_HFLAG_FBNSLOT:
gen_goto_tb(ctx, 0, ctx->base.pc_next + insn_bytes);