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Re: [RFC] ich9:cpuhp: add support for cpu hot-unplug with SMI broadcast
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From: |
Igor Mammedov |
|
Subject: |
Re: [RFC] ich9:cpuhp: add support for cpu hot-unplug with SMI broadcast enabled |
|
Date: |
Fri, 27 Nov 2020 12:47:34 +0100 |
On Thu, 26 Nov 2020 20:10:59 -0800
Ankur Arora <ankur.a.arora@oracle.com> wrote:
> On 2020-11-26 12:38 p.m., Igor Mammedov wrote:
> > On Thu, 26 Nov 2020 12:17:27 +0100
> > Laszlo Ersek <lersek@redhat.com> wrote:
> >
> >> On 11/24/20 13:25, Igor Mammedov wrote:
> >>> If firmware negotiates ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT feature,
> >>> OSPM on CPU eject will set bit #4 in CPU hotplug block for to be
> >>> ejected CPU to mark it for removal by firmware and trigger SMI
> >>> upcall to let firmware do actual eject.
> >>>
> >>> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> >>> ---
> >>> PS:
> >>> - abuse 5.1 machine type for now to turn off unplug feature
> >>> (it will be moved to 5.2 machine type once new merge window is open)
> >>> ---
> >>> include/hw/acpi/cpu.h | 2 ++
> >>> docs/specs/acpi_cpu_hotplug.txt | 11 +++++++++--
> >>> hw/acpi/cpu.c | 18 ++++++++++++++++--
> >>> hw/i386/acpi-build.c | 5 +++++
> >>> hw/i386/pc.c | 1 +
> >>> hw/isa/lpc_ich9.c | 2 +-
> >>> 6 files changed, 34 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/include/hw/acpi/cpu.h b/include/hw/acpi/cpu.h
> >>> index 0eeedaa491..999caaf510 100644
> >>> --- a/include/hw/acpi/cpu.h
> >>> +++ b/include/hw/acpi/cpu.h
> >>> @@ -22,6 +22,7 @@ typedef struct AcpiCpuStatus {
> >>> uint64_t arch_id;
> >>> bool is_inserting;
> >>> bool is_removing;
> >>> + bool fw_remove;
> >>> uint32_t ost_event;
> >>> uint32_t ost_status;
> >>> } AcpiCpuStatus;
> >>> @@ -50,6 +51,7 @@ void cpu_hotplug_hw_init(MemoryRegion *as, Object
> >>> *owner,
> >>> typedef struct CPUHotplugFeatures {
> >>> bool acpi_1_compatible;
> >>> bool has_legacy_cphp;
> >>> + bool fw_unplugs_cpu;
> >>> const char *smi_path;
> >>> } CPUHotplugFeatures;
> >>>
> >>> diff --git a/docs/specs/acpi_cpu_hotplug.txt
> >>> b/docs/specs/acpi_cpu_hotplug.txt
> >>> index 9bb22d1270..f68ef6e06c 100644
> >>> --- a/docs/specs/acpi_cpu_hotplug.txt
> >>> +++ b/docs/specs/acpi_cpu_hotplug.txt
> >>> @@ -57,7 +57,11 @@ read access:
> >>> It's valid only when bit 0 is set.
> >>> 2: Device remove event, used to distinguish device for which
> >>> no device eject request to OSPM was issued.
> >>> - 3-7: reserved and should be ignored by OSPM
> >>> + 3: reserved and should be ignored by OSPM
> >>> + 4: if set to 1, OSPM requests firmware to perform device
> >>> eject,
> >>> + firmware shall clear this event by writing 1 into it
> >>> before
> >>
> >> (1) s/clear this event/clear this event bit/
> >>
> >>> + performing device eject.
> >>
> >> (2) move the second and third lines ("firmware shall clear....") over to
> >> the write documentation, below? In particular:
> >>
> >>> + 5-7: reserved and should be ignored by OSPM
> >>> [0x5-0x7] reserved
> >>> [0x8] Command data: (DWORD access)
> >>> contains 0 unless value last stored in 'Command field' is one
> >>> of:
> >>> @@ -82,7 +86,10 @@ write access:
> >>> selected CPU device
> >>> 3: if set to 1 initiates device eject, set by OSPM when it
> >>> triggers CPU device removal and calls _EJ0 method
> >>> - 4-7: reserved, OSPM must clear them before writing to
> >>> register
> >>> + 4: if set to 1 OSPM hands over device eject to firmware,
> >>> + Firmware shall issue device eject request as described
> >>> above
> >>> + (bit #3) and OSPM should not touch device eject bit (#3),
> >>>
> >>
> >> (3) it would be clearer if we documented the exact bit writing order
> >> here:
> >> - clear bit#4, *then* set bit#3 (two write accesses)
> >> - versus clear bit#4 *and* set bit#3 (single access)
> >
> > I was thinking that FW should not bother with clearing bit #4,
> > and QEMU should clear it when handling write to bit #3.
> > (it looks like I forgot to actually do that)
>
> Why involve the firmware with bit #3 at all? If the firmware only reads bit #4
> to detect fw_remove and then write (and thus reset) bit #4, isn't that
> good enough?
That would needlessly complicate code on QEMU side and I don't want to
overload bit #4 with another semantics, and we already have bit #3 that
does eject. So unless there are issues with that, I'd stick to using
bit #3 for eject.
>
>
> >
> >>
> >>
> >>
> >>> + 5-7: reserved, OSPM must clear them before writing to
> >>> register
> >>> [0x5] Command field: (1 byte access)
> >>> value:
> >>> 0: selects a CPU device with inserting/removing events and
> >>> diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
> >>> index f099b50927..09d2f20dae 100644
> >>> --- a/hw/acpi/cpu.c
> >>> +++ b/hw/acpi/cpu.c
> >>> @@ -71,6 +71,7 @@ static uint64_t cpu_hotplug_rd(void *opaque, hwaddr
> >>> addr, unsigned size)
> >>> val |= cdev->cpu ? 1 : 0;
> >>> val |= cdev->is_inserting ? 2 : 0;
> >>> val |= cdev->is_removing ? 4 : 0;
> >>> + val |= cdev->fw_remove ? 16 : 0;
> >>> trace_cpuhp_acpi_read_flags(cpu_st->selector, val);
> >>> break;
> >>> case ACPI_CPU_CMD_DATA_OFFSET_RW:
> >>> @@ -148,6 +149,8 @@ static void cpu_hotplug_wr(void *opaque, hwaddr addr,
> >>> uint64_t data,
> >>> hotplug_ctrl = qdev_get_hotplug_handler(dev);
> >>> hotplug_handler_unplug(hotplug_ctrl, dev, NULL);
> >>> object_unparent(OBJECT(dev));
> >>> + } else if (data & 16) {
> >>> + cdev->fw_remove = !cdev->fw_remove;
> >>
> >> hm... so I guess the ACPI code will first write bit#4 to flip
> >> "fw_remove" from "off" to "on". Then the firmware will write bit#4 to
> >> flip "fw_remove" back to "off". And finally, the firmware will write
> >> bit#3 (strictly as a separate access) to unplug the CPU.
> > sorry for confusion in doc vs impl, FW should only read bit #4, as for bit
> > #3 only write.
> >
> >> (4) But anyway, taking a step back: what do we need the new bit for?
> >>
> >>> }
> >>> break;
> >>> case ACPI_CPU_CMD_OFFSET_WR:
> >>> @@ -332,6 +335,7 @@ const VMStateDescription vmstate_cpu_hotplug = {
> >>> #define CPU_INSERT_EVENT "CINS"
> >>> #define CPU_REMOVE_EVENT "CRMV"
> >>> #define CPU_EJECT_EVENT "CEJ0"
> >>> +#define CPU_FW_EJECT_EVENT "CEJF"
> >>>
> >>> void build_cpus_aml(Aml *table, MachineState *machine,
> >>> CPUHotplugFeatures opts,
> >>> hwaddr io_base,
> >>> @@ -384,7 +388,10 @@ void build_cpus_aml(Aml *table, MachineState
> >>> *machine, CPUHotplugFeatures opts,
> >>> aml_append(field, aml_named_field(CPU_REMOVE_EVENT, 1));
> >>> /* initiates device eject, write only */
> >>> aml_append(field, aml_named_field(CPU_EJECT_EVENT, 1));
> >>> - aml_append(field, aml_reserved_field(4));
> >>> + aml_append(field, aml_reserved_field(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(2));
> >>> aml_append(field, aml_named_field(CPU_COMMAND, 8));
> >>> aml_append(cpu_ctrl_dev, field);
> >>>
> >>> @@ -419,6 +426,7 @@ void build_cpus_aml(Aml *table, MachineState
> >>> *machine, CPUHotplugFeatures opts,
> >>> Aml *ins_evt = aml_name("%s.%s", cphp_res_path,
> >>> CPU_INSERT_EVENT);
> >>> Aml *rm_evt = aml_name("%s.%s", cphp_res_path,
> >>> CPU_REMOVE_EVENT);
> >>> Aml *ej_evt = aml_name("%s.%s", cphp_res_path, CPU_EJECT_EVENT);
> >>> + Aml *fw_ej_evt = aml_name("%s.%s", cphp_res_path,
> >>> CPU_FW_EJECT_EVENT);
> >>>
> >>> aml_append(cpus_dev, aml_name_decl("_HID",
> >>> aml_string("ACPI0010")));
> >>> aml_append(cpus_dev, aml_name_decl("_CID",
> >>> aml_eisaid("PNP0A05")));
> >>> @@ -461,7 +469,13 @@ void build_cpus_aml(Aml *table, MachineState
> >>> *machine, CPUHotplugFeatures opts,
> >>>
> >>> aml_append(method, aml_acquire(ctrl_lock, 0xFFFF));
> >>> aml_append(method, aml_store(idx, cpu_selector));
> >>> - aml_append(method, aml_store(one, ej_evt));
> >>> + if (opts.fw_unplugs_cpu) {
> >>> + aml_append(method, aml_store(one, fw_ej_evt));
> >>> + aml_append(method, aml_store(aml_int(OVMF_CPUHP_SMI_CMD),
> >>> + aml_name("%s", opts.smi_path)));
> >>> + } else {
> >>> + aml_append(method, aml_store(one, ej_evt));
> >>> + }
> >>> aml_append(method, aml_release(ctrl_lock));
> >>> }
> >>> aml_append(cpus_dev, method);
> >>
> >> Hmmm, OK, let me parse this.
> >>
> >> Assume there is a big bunch of device_del QMP commands, QEMU marks the
> >> "remove" event pending on the corresponding set of CPUs, plus also makes
> >> the ACPI interrupt pending. The ACPI interrupt handler in the OS runs,
> >> and calls CSCN. CSCN runs a loop, and for each CPU where the remove
> >> event is pending, notifies the OS one by one. The OS in turn forgets
> >> about the subject CPU, and calls the _EJ0 method on the affected CPU
> >> ACPI object. The _EJ0 method on the CPU ACPI object calls CEJ0, passing
> >> in the affected CPU's identifier.
> >>
> >> The above hunk modifies the CEJ0 method.
> >>
> >> (5) Question: pre-patch, both the CSCN method and the CEJ0 method
> >> acquire the CPLK lock, but CEJ0 is actually called within CSCN
> >> (indirectly, with the OS's cooperation). Is CPLK a recursive lock?
> > Theoretically scep supports recursive mutexes but I don't think it's the
> > case here.
> >
> > Considering it works currently, I think OS implements Notify event as async.
> > hence no clash wrt mutex. If EJ0 were handled within CSCN context,
> > EJ0 would mess cpu_selector value that CSCN is also using.
>
> From my read of the Linux code, yeah, the EJ0 execution happens in an
> async worker on CPU 0 which first detaches the CPU and then executes EJ0.
> >> Anyway, let's see the CEJ0 modification. After the OS is done forgetting
> >> about the CPU, the CEJ0 method no longer unplugs the CPU, instead it
> >> sets the new bit#4 in the register block, and raises an SMI.
> >>
> >> (6) So that's one SMI per CPU being removed. Is that OK?
> >
> > I guess it has performance penalty but there is nothing we can do about it,
> > OSPM does EJ0 calls asynchronously.
> >
> >> (7) What if there are asynchronous plugs going on, and the firmware
> >> notices them in the register block? ... Hm, I hope that should be OK,
> >> because ultimately the CSCN method will learn about those too, and
> >> inform the OS. On plug, the firmware doesn't modify the register block.
> > shouldn't be issue (modulo bugs, I haven't tried to hot add and hot remove
> > the same CPU at the same time)
>
> Yeah I was wondering what would happen for simultaneous hot add and remove.
> I guess we would always do remove first and then the add, unless we hit
> the break due to max_cpus_per_pass and switch to hot-add mode.
>
> >
> > i.e.
> > (QEMU) pause
> > (QEMU) device_add
> > (QEMU) device_del
> > (QEMU) cont
looking at current CPU_SCAN_METHOD
it will notice and process insert event only.
Remove event will be pending till the next cpu hotplug SCI.
(i.e. next time user hot(un)plugs a cpu)
not sure that such use case is worth fixing though.
> >
> >> Ah! OK. I think I understand why bit#4 is important. The firmware may
> >> notice pending remove events, but it must not act upon them -- it must
> >> simply ignore them -- unless bit#4 is also set. Bit#2 set with bit#4
> >> clear means the event is pending (QEMU got a device_del), but the OS has
> >> not forgotten about the CPU yet -- so the firmware must not unplug it
> >> yet. When the modified CEJ0 method runs, it sets bit#4 in addition to
> >> the already set bit#2, advertising that the OS has *already* abandoned
> >> the CPU.
> > firmware should ignore bit #2, it doesn't mean anything to it, OSPM might
> > ignore or nonsupport CPU removal. What firmware must care about is bit #4,
> > which tells it that OSPM is done with CPU and asks for to be removed by
> > firmware.
>
> In my other mail, I was suggesting that the guest OS not reset bit #2 but
> on second thoughts, this makes sense.
>
>
> Thanks
> Ankur
>
> >
> >>
> >> This means we'll have to modify the QemuCpuhpCollectApicIds() function
> >> in OVMF as well -- for collecting a CPU for unplug, just bit#2
> >> (QEMU_CPUHP_STAT_REMOVE) is insufficient -- on such CPUs, the OS may
> >> still be executing threads.
> >>
> >> OK, this approach sounds plausible to me.
> >>
> >> (8) Please extend the description of bit#2 in the "status flags read
> >> access" section: "firmware must ignore bit#2 unless bit#4 is set".
> >>
> >>
> >>
> >>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> >>> index 1f5c211245..475e76f514 100644
> >>> --- a/hw/i386/acpi-build.c
> >>> +++ b/hw/i386/acpi-build.c
> >>> @@ -96,6 +96,7 @@ typedef struct AcpiPmInfo {
> >>> bool s4_disabled;
> >>> bool pcihp_bridge_en;
> >>> bool smi_on_cpuhp;
> >>> + bool smi_on_cpu_unplug;
> >>> bool pcihp_root_en;
> >>> uint8_t s4_val;
> >>> AcpiFadtData fadt;
> >>> @@ -197,6 +198,7 @@ static void acpi_get_pm_info(MachineState *machine,
> >>> AcpiPmInfo *pm)
> >>> pm->pcihp_io_base = 0;
> >>> pm->pcihp_io_len = 0;
> >>> pm->smi_on_cpuhp = false;
> >>> + pm->smi_on_cpu_unplug = false;
> >>>
> >>> assert(obj);
> >>> init_common_fadt_data(machine, obj, &pm->fadt);
> >>> @@ -220,6 +222,8 @@ static void acpi_get_pm_info(MachineState *machine,
> >>> AcpiPmInfo *pm)
> >>> pm->cpu_hp_io_base = ICH9_CPU_HOTPLUG_IO_BASE;
> >>> pm->smi_on_cpuhp =
> >>> !!(smi_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT));
> >>> + pm->smi_on_cpu_unplug =
> >>> + !!(smi_features &
> >>> BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT));
> >>> }
> >>>
> >>> /* The above need not be conditional on machine type because the
> >>> reset port
> >>> @@ -1582,6 +1586,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >>> CPUHotplugFeatures opts = {
> >>> .acpi_1_compatible = true, .has_legacy_cphp = true,
> >>> .smi_path = pm->smi_on_cpuhp ? "\\_SB.PCI0.SMI0.SMIC" :
> >>> NULL,
> >>> + .fw_unplugs_cpu = pm->smi_on_cpu_unplug,
> >>> };
> >>> build_cpus_aml(dsdt, machine, opts, pm->cpu_hp_io_base,
> >>> "\\_SB.PCI0", "\\_GPE._E02");
> >>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> >>> index 17b514d1da..2952a00fe6 100644
> >>> --- a/hw/i386/pc.c
> >>> +++ b/hw/i386/pc.c
> >>> @@ -99,6 +99,7 @@
> >>>
> >>> GlobalProperty pc_compat_5_1[] = {
> >>> { "ICH9-LPC", "x-smi-cpu-hotplug", "off" },
> >>> + { "ICH9-LPC", "x-smi-cpu-hotunplug", "off" },
> >>> };
> >>> const size_t pc_compat_5_1_len = G_N_ELEMENTS(pc_compat_5_1);
> >>>
> >>> diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
> >>> index 087a18d04d..8c667b7166 100644
> >>> --- a/hw/isa/lpc_ich9.c
> >>> +++ b/hw/isa/lpc_ich9.c
> >>> @@ -770,7 +770,7 @@ static Property ich9_lpc_properties[] = {
> >>> DEFINE_PROP_BIT64("x-smi-cpu-hotplug", ICH9LPCState,
> >>> smi_host_features,
> >>> ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT, true),
> >>> DEFINE_PROP_BIT64("x-smi-cpu-hotunplug", ICH9LPCState,
> >>> smi_host_features,
> >>> - ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT, false),
> >>> + ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT, true),
> >>> DEFINE_PROP_END_OF_LIST(),
> >>> };
> >>>
> >>>
> >>
> >> (9) You have to extend smi_features_ok_callback() as well -- it is
> >> invalid for the firmware to negotiate unplug, without negotiating plug.
> >>
> >> In fact, as far as I can tell, that would even crash QEMU, given this
> >> patch. Because, "opts.smi_path" would be set to NULL, but
> >> "opts.fw_unplugs_cpu" would be set to "true". As a consequence, the
> >> CPU_EJECT_METHOD change above would call aml_name("%s", NULL).
> >>
> >> So something like the following looks necessary:
> >
> > Thanks for suggestions,
> > I'll respin v2 with your feedback included.
> >
> >>
> >>> diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
> >>> index 8c667b7166c7..5bc3f212fe77 100644
> >>> --- a/hw/isa/lpc_ich9.c
> >>> +++ b/hw/isa/lpc_ich9.c
> >>> @@ -366,6 +366,7 @@ static void smi_features_ok_callback(void *opaque)
> >>> {
> >>> ICH9LPCState *lpc = opaque;
> >>> uint64_t guest_features;
> >>> + uint64_t guest_cpu_hotplug_features;
> >>>
> >>> if (lpc->smi_features_ok) {
> >>> /* negotiation already complete, features locked */
> >>> @@ -378,9 +379,11 @@ static void smi_features_ok_callback(void *opaque)
> >>> /* guest requests invalid features, leave @features_ok at zero
> >>> */
> >>> return;
> >>> }
> >>> + guest_cpu_hotplug_features = guest_features &
> >>> +
> >>> (BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT) |
> >>> +
> >>> BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT));
> >>> if (!(guest_features & BIT_ULL(ICH9_LPC_SMI_F_BROADCAST_BIT)) &&
> >>> - guest_features & (BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT) |
> >>> - BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT))) {
> >>> + guest_cpu_hotplug_features) {
> >>> /*
> >>> * cpu hot-[un]plug with SMI requires SMI broadcast,
> >>> * leave @features_ok at zero
> >>> @@ -388,6 +391,12 @@ static void smi_features_ok_callback(void *opaque)
> >>> return;
> >>> }
> >>>
> >>> + if (guest_cpu_hotplug_features ==
> >>> + BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT)) {
> >>> + /* cpu hot-unplug is unsupported without cpu-hotplug */
> >>> + return;
> >>> + }
> >>> +
> >>> /* valid feature subset requested, lock it down, report success */
> >>> lpc->smi_negotiated_features = guest_features;
> >>> lpc->smi_features_ok = 1;
> >>
> >>
> >> (10) It would be nice to separate this work into multiple patches. I
> >> propose:
> >>
> >> - [PATCH 1/5] x86: ich9: factor out "guest_cpu_hotplug_features"
> >>
> >>> hw/isa/lpc_ich9.c | 7 +++++--
> >>> 1 file changed, 5 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
> >>> index 087a18d04de4..c46eefd13fd4 100644
> >>> --- a/hw/isa/lpc_ich9.c
> >>> +++ b/hw/isa/lpc_ich9.c
> >>> @@ -366,6 +366,7 @@ static void smi_features_ok_callback(void *opaque)
> >>> {
> >>> ICH9LPCState *lpc = opaque;
> >>> uint64_t guest_features;
> >>> + uint64_t guest_cpu_hotplug_features;
> >>>
> >>> if (lpc->smi_features_ok) {
> >>> /* negotiation already complete, features locked */
> >>> @@ -378,9 +379,11 @@ static void smi_features_ok_callback(void *opaque)
> >>> /* guest requests invalid features, leave @features_ok at zero
> >>> */
> >>> return;
> >>> }
> >>> + guest_cpu_hotplug_features = guest_features &
> >>> +
> >>> (BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT) |
> >>> +
> >>> BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT));
> >>> if (!(guest_features & BIT_ULL(ICH9_LPC_SMI_F_BROADCAST_BIT)) &&
> >>> - guest_features & (BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT) |
> >>> - BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT))) {
> >>> + guest_cpu_hotplug_features) {
> >>> /*
> >>> * cpu hot-[un]plug with SMI requires SMI broadcast,
> >>> * leave @features_ok at zero
> >>
> >>
> >> - [PATCH 2/5] x86: ich9: let firmware negotiate 'CPU hot-unplug with SMI'
> >> feature
> >>
> >>> hw/i386/pc.c | 1 +
> >>> hw/isa/lpc_ich9.c | 8 +++++++-
> >>> 2 files changed, 8 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> >>> index 17b514d1da50..2952a00fe694 100644
> >>> --- a/hw/i386/pc.c
> >>> +++ b/hw/i386/pc.c
> >>> @@ -99,6 +99,7 @@
> >>>
> >>> GlobalProperty pc_compat_5_1[] = {
> >>> { "ICH9-LPC", "x-smi-cpu-hotplug", "off" },
> >>> + { "ICH9-LPC", "x-smi-cpu-hotunplug", "off" },
> >>> };
> >>> const size_t pc_compat_5_1_len = G_N_ELEMENTS(pc_compat_5_1);
> >>>
> >>> diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
> >>> index c46eefd13fd4..5bc3f212fe77 100644
> >>> --- a/hw/isa/lpc_ich9.c
> >>> +++ b/hw/isa/lpc_ich9.c
> >>> @@ -391,6 +391,12 @@ static void smi_features_ok_callback(void *opaque)
> >>> return;
> >>> }
> >>>
> >>> + if (guest_cpu_hotplug_features ==
> >>> + BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT)) {
> >>> + /* cpu hot-unplug is unsupported without cpu-hotplug */
> >>> + return;
> >>> + }
> >>> +
> >>> /* valid feature subset requested, lock it down, report success */
> >>> lpc->smi_negotiated_features = guest_features;
> >>> lpc->smi_features_ok = 1;
> >>> @@ -773,7 +779,7 @@ static Property ich9_lpc_properties[] = {
> >>> DEFINE_PROP_BIT64("x-smi-cpu-hotplug", ICH9LPCState,
> >>> smi_host_features,
> >>> ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT, true),
> >>> DEFINE_PROP_BIT64("x-smi-cpu-hotunplug", ICH9LPCState,
> >>> smi_host_features,
> >>> - ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT, false),
> >>> + ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT, true),
> >>> DEFINE_PROP_END_OF_LIST(),
> >>> };
> >>>
> >>
> >>
> >> - [PATCH 3/5] x86: acpi: introduce AcpiPmInfo::smi_on_cpu_unplug
> >>
> >>> hw/i386/acpi-build.c | 4 ++++
> >>> 1 file changed, 4 insertions(+)
> >>>
> >>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> >>> index 1f5c2112452a..9036e5594c92 100644
> >>> --- a/hw/i386/acpi-build.c
> >>> +++ b/hw/i386/acpi-build.c
> >>> @@ -96,6 +96,7 @@ typedef struct AcpiPmInfo {
> >>> bool s4_disabled;
> >>> bool pcihp_bridge_en;
> >>> bool smi_on_cpuhp;
> >>> + bool smi_on_cpu_unplug;
> >>> bool pcihp_root_en;
> >>> uint8_t s4_val;
> >>> AcpiFadtData fadt;
> >>> @@ -197,6 +198,7 @@ static void acpi_get_pm_info(MachineState *machine,
> >>> AcpiPmInfo *pm)
> >>> pm->pcihp_io_base = 0;
> >>> pm->pcihp_io_len = 0;
> >>> pm->smi_on_cpuhp = false;
> >>> + pm->smi_on_cpu_unplug = false;
> >>>
> >>> assert(obj);
> >>> init_common_fadt_data(machine, obj, &pm->fadt);
> >>> @@ -220,6 +222,8 @@ static void acpi_get_pm_info(MachineState *machine,
> >>> AcpiPmInfo *pm)
> >>> pm->cpu_hp_io_base = ICH9_CPU_HOTPLUG_IO_BASE;
> >>> pm->smi_on_cpuhp =
> >>> !!(smi_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT));
> >>> + pm->smi_on_cpu_unplug =
> >>> + !!(smi_features &
> >>> BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT));
> >>> }
> >>>
> >>> /* The above need not be conditional on machine type because the
> >>> reset port
> >>
> >>
> >> - [PATCH 4/5] acpi: cpuhp: introduce 'firmware performs eject'
> >> status/control bits
> >>
> >>> docs/specs/acpi_cpu_hotplug.txt | 11 +++++++++--
> >>> include/hw/acpi/cpu.h | 1 +
> >>> hw/acpi/cpu.c | 3 +++
> >>> 3 files changed, 13 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/docs/specs/acpi_cpu_hotplug.txt
> >>> b/docs/specs/acpi_cpu_hotplug.txt
> >>> index 9bb22d1270a9..f68ef6e06c7a 100644
> >>> --- a/docs/specs/acpi_cpu_hotplug.txt
> >>> +++ b/docs/specs/acpi_cpu_hotplug.txt
> >>> @@ -57,7 +57,11 @@ read access:
> >>> It's valid only when bit 0 is set.
> >>> 2: Device remove event, used to distinguish device for which
> >>> no device eject request to OSPM was issued.
> >>> - 3-7: reserved and should be ignored by OSPM
> >>> + 3: reserved and should be ignored by OSPM
> >>> + 4: if set to 1, OSPM requests firmware to perform device
> >>> eject,
> >>> + firmware shall clear this event by writing 1 into it before
> >>> + performing device eject.
> >>> + 5-7: reserved and should be ignored by OSPM
> >>> [0x5-0x7] reserved
> >>> [0x8] Command data: (DWORD access)
> >>> contains 0 unless value last stored in 'Command field' is one
> >>> of:
> >>> @@ -82,7 +86,10 @@ write access:
> >>> selected CPU device
> >>> 3: if set to 1 initiates device eject, set by OSPM when it
> >>> triggers CPU device removal and calls _EJ0 method
> >>> - 4-7: reserved, OSPM must clear them before writing to
> >>> register
> >>> + 4: if set to 1 OSPM hands over device eject to firmware,
> >>> + Firmware shall issue device eject request as described
> >>> above
> >>> + (bit #3) and OSPM should not touch device eject bit (#3),
> >>> + 5-7: reserved, OSPM must clear them before writing to
> >>> register
> >>> [0x5] Command field: (1 byte access)
> >>> value:
> >>> 0: selects a CPU device with inserting/removing events and
> >>> diff --git a/include/hw/acpi/cpu.h b/include/hw/acpi/cpu.h
> >>> index 0eeedaa491c1..d71edde456f2 100644
> >>> --- a/include/hw/acpi/cpu.h
> >>> +++ b/include/hw/acpi/cpu.h
> >>> @@ -22,6 +22,7 @@ typedef struct AcpiCpuStatus {
> >>> uint64_t arch_id;
> >>> bool is_inserting;
> >>> bool is_removing;
> >>> + bool fw_remove;
> >>> uint32_t ost_event;
> >>> uint32_t ost_status;
> >>> } AcpiCpuStatus;
> >>> diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
> >>> index f099b5092730..3dc83d73e20b 100644
> >>> --- a/hw/acpi/cpu.c
> >>> +++ b/hw/acpi/cpu.c
> >>> @@ -71,6 +71,7 @@ static uint64_t cpu_hotplug_rd(void *opaque, hwaddr
> >>> addr, unsigned size)
> >>> val |= cdev->cpu ? 1 : 0;
> >>> val |= cdev->is_inserting ? 2 : 0;
> >>> val |= cdev->is_removing ? 4 : 0;
> >>> + val |= cdev->fw_remove ? 16 : 0;
> >>> trace_cpuhp_acpi_read_flags(cpu_st->selector, val);
> >>> break;
> >>> case ACPI_CPU_CMD_DATA_OFFSET_RW:
> >>> @@ -148,6 +149,8 @@ static void cpu_hotplug_wr(void *opaque, hwaddr addr,
> >>> uint64_t data,
> >>> hotplug_ctrl = qdev_get_hotplug_handler(dev);
> >>> hotplug_handler_unplug(hotplug_ctrl, dev, NULL);
> >>> object_unparent(OBJECT(dev));
> >>> + } else if (data & 16) {
> >>> + cdev->fw_remove = !cdev->fw_remove;
> >>> }
> >>> break;
> >>> case ACPI_CPU_CMD_OFFSET_WR:
> >>
> >>
> >> - [PATCH 5/5] x86: acpi: let the firmware handle pending "CPU remove"
> >> events in SMM
> >>
> >>> include/hw/acpi/cpu.h | 1 +
> >>> hw/acpi/cpu.c | 15 +++++++++++++--
> >>> hw/i386/acpi-build.c | 1 +
> >>> 3 files changed, 15 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/include/hw/acpi/cpu.h b/include/hw/acpi/cpu.h
> >>> index d71edde456f2..999caaf51060 100644
> >>> --- a/include/hw/acpi/cpu.h
> >>> +++ b/include/hw/acpi/cpu.h
> >>> @@ -51,6 +51,7 @@ void cpu_hotplug_hw_init(MemoryRegion *as, Object
> >>> *owner,
> >>> typedef struct CPUHotplugFeatures {
> >>> bool acpi_1_compatible;
> >>> bool has_legacy_cphp;
> >>> + bool fw_unplugs_cpu;
> >>> const char *smi_path;
> >>> } CPUHotplugFeatures;
> >>>
> >>> diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
> >>> index 3dc83d73e20b..09d2f20daec0 100644
> >>> --- a/hw/acpi/cpu.c
> >>> +++ b/hw/acpi/cpu.c
> >>> @@ -335,6 +335,7 @@ const VMStateDescription vmstate_cpu_hotplug = {
> >>> #define CPU_INSERT_EVENT "CINS"
> >>> #define CPU_REMOVE_EVENT "CRMV"
> >>> #define CPU_EJECT_EVENT "CEJ0"
> >>> +#define CPU_FW_EJECT_EVENT "CEJF"
> >>>
> >>> void build_cpus_aml(Aml *table, MachineState *machine,
> >>> CPUHotplugFeatures opts,
> >>> hwaddr io_base,
> >>> @@ -387,7 +388,10 @@ void build_cpus_aml(Aml *table, MachineState
> >>> *machine, CPUHotplugFeatures opts,
> >>> aml_append(field, aml_named_field(CPU_REMOVE_EVENT, 1));
> >>> /* initiates device eject, write only */
> >>> aml_append(field, aml_named_field(CPU_EJECT_EVENT, 1));
> >>> - aml_append(field, aml_reserved_field(4));
> >>> + aml_append(field, aml_reserved_field(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(2));
> >>> aml_append(field, aml_named_field(CPU_COMMAND, 8));
> >>> aml_append(cpu_ctrl_dev, field);
> >>>
> >>> @@ -422,6 +426,7 @@ void build_cpus_aml(Aml *table, MachineState
> >>> *machine, CPUHotplugFeatures opts,
> >>> Aml *ins_evt = aml_name("%s.%s", cphp_res_path,
> >>> CPU_INSERT_EVENT);
> >>> Aml *rm_evt = aml_name("%s.%s", cphp_res_path,
> >>> CPU_REMOVE_EVENT);
> >>> Aml *ej_evt = aml_name("%s.%s", cphp_res_path, CPU_EJECT_EVENT);
> >>> + Aml *fw_ej_evt = aml_name("%s.%s", cphp_res_path,
> >>> CPU_FW_EJECT_EVENT);
> >>>
> >>> aml_append(cpus_dev, aml_name_decl("_HID",
> >>> aml_string("ACPI0010")));
> >>> aml_append(cpus_dev, aml_name_decl("_CID",
> >>> aml_eisaid("PNP0A05")));
> >>> @@ -464,7 +469,13 @@ void build_cpus_aml(Aml *table, MachineState
> >>> *machine, CPUHotplugFeatures opts,
> >>>
> >>> aml_append(method, aml_acquire(ctrl_lock, 0xFFFF));
> >>> aml_append(method, aml_store(idx, cpu_selector));
> >>> - aml_append(method, aml_store(one, ej_evt));
> >>> + if (opts.fw_unplugs_cpu) {
> >>> + aml_append(method, aml_store(one, fw_ej_evt));
> >>> + aml_append(method, aml_store(aml_int(OVMF_CPUHP_SMI_CMD),
> >>> + aml_name("%s", opts.smi_path)));
> >>> + } else {
> >>> + aml_append(method, aml_store(one, ej_evt));
> >>> + }
> >>> aml_append(method, aml_release(ctrl_lock));
> >>> }
> >>> aml_append(cpus_dev, method);
> >>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> >>> index 9036e5594c92..475e76f514ff 100644
> >>> --- a/hw/i386/acpi-build.c
> >>> +++ b/hw/i386/acpi-build.c
> >>> @@ -1586,6 +1586,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >>> CPUHotplugFeatures opts = {
> >>> .acpi_1_compatible = true, .has_legacy_cphp = true,
> >>> .smi_path = pm->smi_on_cpuhp ? "\\_SB.PCI0.SMI0.SMIC" :
> >>> NULL,
> >>> + .fw_unplugs_cpu = pm->smi_on_cpu_unplug,
> >>> };
> >>> build_cpus_aml(dsdt, machine, opts, pm->cpu_hp_io_base,
> >>> "\\_SB.PCI0", "\\_GPE._E02");
> >>
> >> Thanks!
> >> Laszlo
> >>
> >>
> >
>
Re: [RFC] ich9:cpuhp: add support for cpu hot-unplug with SMI broadcast enabled, Ankur Arora, 2020/11/26