Hi Igor, > From: Igor Mammedov <[email protected]> > Sent: Friday, October 18, 2024 3:25 PM > To: Salil Mehta <[email protected]> > Cc: [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; Jonathan Cameron > <[email protected]>; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected]; zhukeqian > <[email protected]>; wangxiongfeng (C) > <[email protected]>; wangyanan (Y) > <[email protected]>; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; Linuxarm <[email protected]>; > [email protected] > Subject: Re: [PATCH V1 3/4] hw/acpi: Reflect ACPI vCPU {present,enabled} > states in ACPI _STA.{PRES,ENA} Bits > > On Mon, 14 Oct 2024 20:22:04 +0100 > Salil Mehta <[email protected]> wrote: > > > Reflect the ACPI CPU hotplug `is_{present, enabled}` states in the > > `_STA.PRES` > > (presence) and `_STA.ENA` (enabled) bits when the guest kernel > > evaluates the ACPI `_STA` method during initialization, as well as > > when vCPUs are hot-plugged or hot-unplugged. The presence of > unplugged > > vCPUs may need to be deliberately > > *simulated* at the ACPI level to maintain a *persistent* view of vCPUs > > for the guest kernel. > > given questionable future of is_present/is_enabled fields, it probably > premature to review this part.
Sure, let us discuss the pain points. > The only thing, I have to say here is repeating spec/doc update patch > describing how it should work should come 1st, so that we could compare > this impl. with it. >From the user perspective, there should not be any change in how he plug/unplugs the ARM vCPUs. This is a requirement, as we have to assists folks who wants to migrate from x86 world to ARM world seamlessly (without affecting performance parameters) and this feature is one small part of that bigger effort. > > Signed-off-by: Salil Mehta <[email protected]> > > --- > > hw/acpi/cpu.c | 26 ++++++++++++++++++++++---- > > 1 file changed, 22 insertions(+), 4 deletions(-) > > > > diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c index > > 700aa855e9..23ea2b9c70 100644 > > --- a/hw/acpi/cpu.c > > +++ b/hw/acpi/cpu.c > > @@ -63,10 +63,11 @@ static uint64_t cpu_hotplug_rd(void *opaque, > hwaddr addr, unsigned size) > > cdev = &cpu_st->devs[cpu_st->selector]; > > switch (addr) { > > case ACPI_CPU_FLAGS_OFFSET_RW: /* pack and return is_* fields */ > > - val |= cdev->cpu ? 1 : 0; > > + val |= cdev->is_enabled ? 1 : 0; > > val |= cdev->is_inserting ? 2 : 0; > > val |= cdev->is_removing ? 4 : 0; > > val |= cdev->fw_remove ? 16 : 0; > > + val |= cdev->is_present ? 32 : 0; > > trace_cpuhp_acpi_read_flags(cpu_st->selector, val); > > break; > > case ACPI_CPU_CMD_DATA_OFFSET_RW: > > @@ -376,6 +377,7 @@ const VMStateDescription vmstate_cpu_hotplug = > { > > #define CPU_REMOVE_EVENT "CRMV" > > #define CPU_EJECT_EVENT "CEJ0" > > #define CPU_FW_EJECT_EVENT "CEJF" > > +#define CPU_PRESENT "CPRS" > > > > void build_cpus_aml(Aml *table, MachineState *machine, > CPUHotplugFeatures opts, > > build_madt_cpu_fn build_madt_cpu, hwaddr > > base_addr, @@ -436,7 +438,9 @@ void build_cpus_aml(Aml *table, > MachineState *machine, CPUHotplugFeatures opts, > > aml_append(field, aml_named_field(CPU_EJECT_EVENT, 1)); > > /* tell firmware to do device eject, write only */ > > aml_append(field, aml_named_field(CPU_FW_EJECT_EVENT, 1)); > > - aml_append(field, aml_reserved_field(3)); > > + /* 1 if present, read only */ > > + aml_append(field, aml_named_field(CPU_PRESENT, 1)); > > + aml_append(field, aml_reserved_field(2)); > > aml_append(field, aml_named_field(CPU_COMMAND, 8)); > > aml_append(cpu_ctrl_dev, field); > > > > @@ -466,6 +470,7 @@ void build_cpus_aml(Aml *table, MachineState > *machine, CPUHotplugFeatures opts, > > Aml *ctrl_lock = aml_name("%s.%s", cphp_res_path, CPU_LOCK); > > Aml *cpu_selector = aml_name("%s.%s", cphp_res_path, > CPU_SELECTOR); > > Aml *is_enabled = aml_name("%s.%s", cphp_res_path, > > CPU_ENABLED); > > + Aml *is_present = aml_name("%s.%s", cphp_res_path, > > + CPU_PRESENT); > > Aml *cpu_cmd = aml_name("%s.%s", cphp_res_path, > CPU_COMMAND); > > Aml *cpu_data = aml_name("%s.%s", cphp_res_path, CPU_DATA); > > Aml *ins_evt = aml_name("%s.%s", cphp_res_path, > > CPU_INSERT_EVENT); @@ -494,13 +499,26 @@ void build_cpus_aml(Aml > *table, MachineState *machine, CPUHotplugFeatures opts, > > { > > Aml *idx = aml_arg(0); > > Aml *sta = aml_local(0); > > + Aml *ifctx2; > > + Aml *else_ctx; > > > > aml_append(method, aml_acquire(ctrl_lock, 0xFFFF)); > > aml_append(method, aml_store(idx, cpu_selector)); > > aml_append(method, aml_store(zero, sta)); > > - ifctx = aml_if(aml_equal(is_enabled, one)); > > + ifctx = aml_if(aml_equal(is_present, one)); > > { > > - aml_append(ifctx, aml_store(aml_int(0xF), sta)); > > + ifctx2 = aml_if(aml_equal(is_enabled, one)); > > + { > > + /* cpu is present and enabled */ > > + aml_append(ifctx2, aml_store(aml_int(0xF), sta)); > > + } > > + aml_append(ifctx, ifctx2); > > + else_ctx = aml_else(); > > + { > > + /* cpu is present but disabled */ > > + aml_append(else_ctx, aml_store(aml_int(0xD), sta)); > > + } > > + aml_append(ifctx, else_ctx); > > } > > aml_append(method, ifctx); > > aml_append(method, aml_release(ctrl_lock)); >
