On 07/06/2017 21:01, 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.
>
> CC: Paolo Bonzini <pbonz...@redhat.com>
> CC: Peter Maydell <peter.mayd...@linaro.org>
> Reviewed-by: Richard Henderson <r...@twiddle.net>
> Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
> Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
> ---
> hw/i386/kvmvapic.c | 82
> ++++++++++++++++++++++++++++++++++--------------------
> 1 file changed, 52 insertions(+), 30 deletions(-)
>
> diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
> index 82a49556af..11b0d494eb 100644
> --- a/hw/i386/kvmvapic.c
> +++ b/hw/i386/kvmvapic.c
> @@ -383,8 +383,7 @@ static void patch_byte(X86CPU *cpu, target_ulong addr,
> uint8_t byte)
> cpu_memory_rw_debug(CPU(cpu), addr, &byte, 1, 1);
> }
>
> -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;
>
> @@ -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(offset),
> 1);
> }
>
> -static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ulong ip)
> +struct PatchInfo {
> + VAPICHandlers *handler;
> + target_ulong ip;
> +};
> +
> +static void do_patch_instruction(CPUState *cs, run_on_cpu_data data)
> {
> - CPUState *cs = CPU(cpu);
> - CPUX86State *env = &cpu->env;
> - VAPICHandlers *handlers;
> + X86CPU *x86_cpu = X86_CPU(cs);
> + CPUX86State *env = &x86_cpu->env;
> + struct PatchInfo *info = (struct PatchInfo *) data.host_ptr;
> + VAPICHandlers *handlers = info->handler;
> + target_ulong ip = info->ip;
> uint8_t opcode[2];
> uint32_t imm32 = 0;
> target_ulong current_pc = 0;
> target_ulong current_cs_base = 0;
> uint32_t current_flags = 0;
>
> - if (smp_cpus == 1) {
> - handlers = &s->rom_state.up;
> - } else {
> - handlers = &s->rom_state.mp;
> - }
> -
> if (!kvm_enabled()) {
> cpu_get_tb_cpu_state(env, ¤t_pc, ¤t_cs_base,
> ¤t_flags);
> @@ -421,48 +421,70 @@ static void patch_instruction(VAPICROMState *s, X86CPU
> *cpu, target_ulong ip)
> }
> }
>
> - pause_all_vcpus();
> -
> cpu_memory_rw_debug(cs, ip, opcode, sizeof(opcode), 0);
>
> 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();
> }
>
> - resume_all_vcpus();
> + g_free(info);
> +}
> +
> +static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ulong ip)
> +{
> + CPUState *cs = CPU(cpu);
> + VAPICHandlers *handlers;
> + struct PatchInfo *info;
> +
> + if (smp_cpus == 1) {
> + handlers = &s->rom_state.up;
> + } else {
> + handlers = &s->rom_state.mp;
> + }
> +
> + info = g_new(struct PatchInfo, 1);
> + info->handler = handlers;
> + info->ip = ip;
>
> 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);
> + const run_on_cpu_func fn = do_patch_instruction;
> +
> + async_safe_run_on_cpu(cs, fn, RUN_ON_CPU_HOST_PTR(info));
> + cs->exception_index = EXCP_INTERRUPT;
> + cpu_loop_exit(cs);
Sorry I forgot about this.
I think these two lines should be a cpu_exit(cpu). In addition, there
is a patch on list "kvm-all: make async_safe_run_on_cpu safe on kvm too"
that let you do this more easily.
Paolo
> }
> +
> + pause_all_vcpus();
> +
> + do_patch_instruction(cs, RUN_ON_CPU_HOST_PTR(info));
> +
> + resume_all_vcpus();
> + g_free(info);
> }
>
> void vapic_report_tpr_access(DeviceState *dev, CPUState *cs, target_ulong ip,
>
