From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35326) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dTQTk-0002T0-Bu for qemu-devel@nongnu.org; Fri, 07 Jul 2017 06:27:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dTQSu-0001dd-2N for qemu-devel@nongnu.org; Fri, 07 Jul 2017 06:26:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53434) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dTQSt-0001cz-Pw for qemu-devel@nongnu.org; Fri, 07 Jul 2017 06:26:24 -0400 References: <20170629071129.29362-1-bobby.prani@gmail.com> <20170629071129.29362-3-bobby.prani@gmail.com> From: Paolo Bonzini Message-ID: Date: Fri, 7 Jul 2017 12:26:18 +0200 MIME-Version: 1.0 In-Reply-To: <20170629071129.29362-3-bobby.prani@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v3 2/2] mttcg/i386: Patch instruction using async_safe_* framework List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pranith Kumar , alex.bennee@linaro.org Cc: qemu-devel@nongnu.org, rth@twiddle.net, ehabkost@redhat.com, Peter Maydell On 29/06/2017 09:11, Pranith Kumar wrote: > In mttcg, calling pause_all_vcpus() during execution from the > generated TBs causes a deadlock if some vCPU is waiting for exclusive > execution in start_exclusive(). Fix this by using the aync_safe_* > framework instead of pausing vcpus for patching instructions. >=20 > CC: Paolo Bonzini > CC: Peter Maydell > Reviewed-by: Richard Henderson > Reviewed-by: Alex Benn=C3=A9e > Signed-off-by: Pranith Kumar > --- > hw/i386/kvmvapic.c | 73 +++++++++++++++++++++++++++++++---------------= -------- > 1 file changed, 42 insertions(+), 31 deletions(-) >=20 > diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c > index 82a49556af..5e0c8219b0 100644 > --- a/hw/i386/kvmvapic.c > +++ b/hw/i386/kvmvapic.c > @@ -383,8 +383,7 @@ static void patch_byte(X86CPU *cpu, target_ulong ad= dr, uint8_t byte) > cpu_memory_rw_debug(CPU(cpu), addr, &byte, 1, 1); > } > =20 > -static void patch_call(VAPICROMState *s, X86CPU *cpu, target_ulong ip, > - uint32_t target) > +static void patch_call(X86CPU *cpu, target_ulong ip, uint32_t target) > { > uint32_t offset; > =20 > @@ -393,23 +392,24 @@ static void patch_call(VAPICROMState *s, X86CPU *= cpu, target_ulong ip, > cpu_memory_rw_debug(CPU(cpu), ip + 1, (void *)&offset, sizeof(offs= et), 1); > } > =20 > -static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ul= ong ip) > +struct PatchInfo { > + VAPICHandlers *handler; > + target_ulong ip; > +}; > + > +static void do_patch_instruction(CPUState *cs, run_on_cpu_data data) > { > - CPUState *cs =3D CPU(cpu); > - CPUX86State *env =3D &cpu->env; > - VAPICHandlers *handlers; > + X86CPU *x86_cpu =3D X86_CPU(cs); > + CPUX86State *env =3D &x86_cpu->env; > + struct PatchInfo *info =3D (struct PatchInfo *) data.host_ptr; > + VAPICHandlers *handlers =3D info->handler; > + target_ulong ip =3D info->ip; > uint8_t opcode[2]; > uint32_t imm32 =3D 0; > target_ulong current_pc =3D 0; > target_ulong current_cs_base =3D 0; > uint32_t current_flags =3D 0; > =20 > - if (smp_cpus =3D=3D 1) { > - handlers =3D &s->rom_state.up; > - } else { > - handlers =3D &s->rom_state.mp; > - } > - > if (!kvm_enabled()) { I think this "if" should stay in patch_instruction(), and... > cpu_get_tb_cpu_state(env, ¤t_pc, ¤t_cs_base, > ¤t_flags); > @@ -421,48 +421,59 @@ static void patch_instruction(VAPICROMState *s, X= 86CPU *cpu, target_ulong ip) > } > } > =20 > - pause_all_vcpus(); > - > cpu_memory_rw_debug(cs, ip, opcode, sizeof(opcode), 0); > =20 > switch (opcode[0]) { > case 0x89: /* mov r32 to r/m32 */ > - patch_byte(cpu, ip, 0x50 + modrm_reg(opcode[1])); /* push reg= */ > - patch_call(s, cpu, ip + 1, handlers->set_tpr); > + patch_byte(x86_cpu, ip, 0x50 + modrm_reg(opcode[1])); /* push= reg */ > + patch_call(x86_cpu, ip + 1, handlers->set_tpr); > break; > case 0x8b: /* mov r/m32 to r32 */ > - patch_byte(cpu, ip, 0x90); > - patch_call(s, cpu, ip + 1, handlers->get_tpr[modrm_reg(opcode[= 1])]); > + patch_byte(x86_cpu, ip, 0x90); > + patch_call(x86_cpu, ip + 1, handlers->get_tpr[modrm_reg(opcode= [1])]); > break; > case 0xa1: /* mov abs to eax */ > - patch_call(s, cpu, ip, handlers->get_tpr[0]); > + patch_call(x86_cpu, ip, handlers->get_tpr[0]); > break; > case 0xa3: /* mov eax to abs */ > - patch_call(s, cpu, ip, handlers->set_tpr_eax); > + patch_call(x86_cpu, ip, handlers->set_tpr_eax); > break; > case 0xc7: /* mov imm32, r/m32 (c7/0) */ > - patch_byte(cpu, ip, 0x68); /* push imm32 */ > + patch_byte(x86_cpu, ip, 0x68); /* push imm32 */ > cpu_memory_rw_debug(cs, ip + 6, (void *)&imm32, sizeof(imm32),= 0); > cpu_memory_rw_debug(cs, ip + 1, (void *)&imm32, sizeof(imm32),= 1); > - patch_call(s, cpu, ip + 5, handlers->set_tpr); > + patch_call(x86_cpu, ip + 5, handlers->set_tpr); > break; > case 0xff: /* push r/m32 */ > - patch_byte(cpu, ip, 0x50); /* push eax */ > - patch_call(s, cpu, ip + 1, handlers->get_tpr_stack); > + patch_byte(x86_cpu, ip, 0x50); /* push eax */ > + patch_call(x86_cpu, ip + 1, handlers->get_tpr_stack); > break; > default: > abort(); > } > =20 > - resume_all_vcpus(); > + g_free(info); > +} > =20 > - if (!kvm_enabled()) { > - /* Both tb_lock and iothread_mutex will be reset when > - * longjmps back into the cpu_exec loop. */ > - tb_lock(); > - tb_gen_code(cs, current_pc, current_cs_base, current_flags, 1)= ; > - cpu_loop_exit_noexc(cs); > +static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ul= ong ip) > +{ > + CPUState *cs =3D CPU(cpu); > + VAPICHandlers *handlers; > + struct PatchInfo *info; > + const run_on_cpu_func fn =3D do_patch_instruction; > + > + if (smp_cpus =3D=3D 1) { > + handlers =3D &s->rom_state.up; > + } else { > + handlers =3D &s->rom_state.mp; > } > + > + info =3D g_new(struct PatchInfo, 1); > + info->handler =3D handlers; > + info->ip =3D ip; > + > + async_safe_run_on_cpu(cs, fn, RUN_ON_CPU_HOST_PTR(info)); > + cpu_exit(cs); ... this cpu_exit is not necessary, since it's already done via async_safe_run_on_cpu->queue_work_on_cpu->qemu_cpu_kick. Thanks, Paolo > } > =20 > void vapic_report_tpr_access(DeviceState *dev, CPUState *cs, target_ul= ong ip, >=20