On 6/11/25 10:49 AM, Igor Mammedov wrote:
> On Wed, 11 Jun 2025 08:47:36 +0200
> Eric Auger <eric.au...@redhat.com> wrote:
>
>> Hi Igor,
>>
>> On 5/27/25 1:58 PM, Igor Mammedov wrote:
>>> On Tue, 27 May 2025 09:40:04 +0200
>>> Eric Auger <eric.au...@redhat.com> wrote:
>>>
>>>> acpi_pcihp VirtMachineClass state flag will allow
>>>> to opt in for acpi pci hotplug. This is guarded by a
>>>> class no_acpi_pcihp flag to manage compats (<= 10.0
>>>> machine types will not support ACPI PCI hotplug).
>>> there is no reason to put an effort in force disabling it
>>> on old machines, as long as code works when explicitly
>>> enabled property on CLI.
>>>
>>> See comment below on how to deal with it
>>>
>>>> Machine state acpi_pcihp flag must be set before the creation
>>>> of the GED device which will use it.
>>>>
>>>> Currently the ACPI PCI HP is turned off by default. This will
>>>> change later on for 10.1 machine type.
>>> one thing to note, is that turning it on by default might
>>> cause change of NIC naming in guest as this brings in
>>> new "_Sxx" slot naming. /so configs tied to nic go down the drain/
>>>
>>> Naming, we have, also happens to be broken wrt spec
>>> (it should be unique system wide, there was a gitlab issue for that,
>>> there is no easy fix that though)
>>>
>>> So I'd leave it disabled by default and let users to turn
>>> it on explicitly when needed.
>>>
>>>> We also introduce properties to allow disabling it.
>>>>
>>>> Signed-off-by: Eric Auger <eric.au...@redhat.com>
>>>> Reviewed-by: Gustavo Romero <gustavo.rom...@linaro.org>
>>>> ---
>>>> include/hw/arm/virt.h | 2 ++
>>>> hw/arm/virt.c | 27 +++++++++++++++++++++++++++
>>>> 2 files changed, 29 insertions(+)
>>>>
>>>> diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
>>>> index 9a1b0f53d2..10ea581f06 100644
>>>> --- a/include/hw/arm/virt.h
>>>> +++ b/include/hw/arm/virt.h
>>>> @@ -129,6 +129,7 @@ struct VirtMachineClass {
>>>> bool no_tcg_lpa2;
>>>> bool no_ns_el2_virt_timer_irq;
>>>> bool no_nested_smmu;
>>>> + bool no_acpi_pcihp;
>>>> };
>>>>
>>>> struct VirtMachineState {
>>>> @@ -150,6 +151,7 @@ struct VirtMachineState {
>>>> bool mte;
>>>> bool dtb_randomness;
>>>> bool second_ns_uart_present;
>>>> + bool acpi_pcihp;
>>>> OnOffAuto acpi;
>>>> VirtGICType gic_version;
>>>> VirtIOMMUType iommu;
>>>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>>>> index 9a6cd085a3..a0deeaf2b3 100644
>>>> --- a/hw/arm/virt.c
>>>> +++ b/hw/arm/virt.c
>>>> @@ -2397,8 +2397,10 @@ static void machvirt_init(MachineState *machine)
>>>> create_pcie(vms);
>>>>
>>>> if (has_ged && aarch64 && firmware_loaded &&
>>>> virt_is_acpi_enabled(vms)) {
>>>> + vms->acpi_pcihp &= !vmc->no_acpi_pcihp;
>>> I don't particularly like no_foo naming as it makes code harder to read
>>> and combined with 'duplicated' field in machine state it make even things
>>> worse.
>>> (if I recall right Philippe was cleaning mess similar flags usage
>>> have introduced with ITS)
>>>
>>> instead of adding machine property (both class and state),
>>> I'd suggest adding the only property to GPE device (akin to what we have in
>>> x86 world)
>>> And then one can meddle with defaults using hw_compat_xxx
>> What I fail to understand is whether you want me to attach this property
>> to the GPEX host bridge device or to the GED device. Comment on patch
> I'd say GED.
>
>> 6/25 seems to indicate you expect it to be attached to the GPEX. I ask
>> here because also the GED device will need to be configured depending on
>> the hp setting. Maybe we can retrieve the info from the gpex at that
>> time. on x86 it is attached to piix4 or ich9 I/O controller hub which do
>> not have direct equivalent on ARM.
> for ARM, equivalent would be GED device which hosts our paravirt acpi
> registers.
OK thank you for the clarification. I will add a property to the GED device.
As the GED device is directly instantiated by the virt machine code (not
exposed to the end user CLI) I guess we still want a virt machine option
that would allow to set the property explicitly from CLI?
Thanks
Eric
>
>> Thanks
>>
>> Eric
>>>
>>>> vms->acpi_dev = create_acpi_ged(vms);
>>>> } else {
>>>> + vms->acpi_pcihp = false;
>>>> create_gpio_devices(vms, VIRT_GPIO, sysmem);
>>>> }
>>>>
>>>> @@ -2593,6 +2595,20 @@ static void virt_set_its(Object *obj, bool value,
>>>> Error **errp)
>>>> vms->its = value;
>>>> }
>>>>
>>>> +static bool virt_get_acpi_pcihp(Object *obj, Error **errp)
>>>> +{
>>>> + VirtMachineState *vms = VIRT_MACHINE(obj);
>>>> +
>>>> + return vms->acpi_pcihp;
>>>> +}
>>>> +
>>>> +static void virt_set_acpi_pcihp(Object *obj, bool value, Error **errp)
>>>> +{
>>>> + VirtMachineState *vms = VIRT_MACHINE(obj);
>>>> +
>>>> + vms->acpi_pcihp = value;
>>>> +}
>>>> +
>>>> static bool virt_get_dtb_randomness(Object *obj, Error **errp)
>>>> {
>>>> VirtMachineState *vms = VIRT_MACHINE(obj);
>>>> @@ -3310,6 +3326,10 @@ static void virt_machine_class_init(ObjectClass
>>>> *oc, const void *data)
>>>> "in ACPI table header."
>>>> "The string may be up to 8
>>>> bytes in size");
>>>>
>>>> + object_class_property_add_bool(oc, "acpi-pcihp",
>>>> + virt_get_acpi_pcihp,
>>>> virt_set_acpi_pcihp);
>>>> + object_class_property_set_description(oc, "acpi-pcihp",
>>>> + "Force ACPI PCI hotplug");
>>>> }
>>>>
>>>> static void virt_instance_init(Object *obj)
>>>> @@ -3344,6 +3364,9 @@ static void virt_instance_init(Object *obj)
>>>> vms->tcg_its = true;
>>>> }
>>>>
>>>> + /* default disallows ACPI PCI hotplug */
>>>> + vms->acpi_pcihp = false;
>>>> +
>>>> /* Default disallows iommu instantiation */
>>>> vms->iommu = VIRT_IOMMU_NONE;
>>>>
>>>> @@ -3394,8 +3417,12 @@ DEFINE_VIRT_MACHINE_AS_LATEST(10, 1)
>>>>
>>>> static void virt_machine_10_0_options(MachineClass *mc)
>>>> {
>>>> + VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
>>>> +
>>>> virt_machine_10_1_options(mc);
>>>> compat_props_add(mc->compat_props, hw_compat_10_0,
>>>> hw_compat_10_0_len);
>>>> + /* 10.0 and earlier do not support ACPI PCI hotplug */
>>>> + vmc->no_acpi_pcihp = true;
>>>> }
>>>> DEFINE_VIRT_MACHINE(10, 0)
>>>>
