Physical CPU hotplug results in (un)setting of ACPI _STA.Present bit. AARCH64 platforms do not support physical CPU hotplug. Virtual CPU hotplug support being implemented toggles ACPI _STA.Enabled Bit to achieve hotplug functionality. This is not same as physical CPU hotplug support.
In future, if ARM architecture supports physical CPU hotplug then the current design of virtual CPU hotplug can be used unchanged. Hence, there is a need for firmware/VMM/Qemu to support evaluation of platform wide capabilitiy related to the *type* of CPU hotplug support present on the platform. OSPM might need this during boot time to correctly initialize the CPUs and other related components in the kernel. NOTE: This implementation will be improved to add the support of *query* in the subsequent versions. This is very minimal support to assist kernel. ASL for the implemented _OSC method: Method (_OSC, 4, NotSerialized) // _OSC: Operating System Capabilities { CreateDWordField (Arg3, Zero, CDW1) If ((Arg0 == ToUUID ("0811b06e-4a27-44f9-8d60-3cbbc22e7b48") /* Platform-wide Capabilities */)) { CreateDWordField (Arg3, 0x04, CDW2) Local0 = CDW2 /* \_SB_._OSC.CDW2 */ If ((Arg1 != One)) { CDW1 |= 0x08 } Local0 &= 0x00800000 If ((CDW2 != Local0)) { CDW1 |= 0x10 } CDW2 = Local0 } Else { CDW1 |= 0x04 } Return (Arg3) } Signed-off-by: Salil Mehta <salil.me...@huawei.com> --- hw/arm/virt-acpi-build.c | 52 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c index cbccd2ca2d..377450dd16 100644 --- a/hw/arm/virt-acpi-build.c +++ b/hw/arm/virt-acpi-build.c @@ -861,6 +861,55 @@ static void build_fadt_rev6(GArray *table_data, BIOSLinker *linker, build_fadt(table_data, linker, &fadt, vms->oem_id, vms->oem_table_id); } +static void build_virt_osc_method(Aml *scope, VirtMachineState *vms) +{ + Aml *if_uuid, *else_uuid, *if_rev, *if_caps_masked, *method; + Aml *a_cdw1 = aml_name("CDW1"); + Aml *a_cdw2 = aml_local(0); + + method = aml_method("_OSC", 4, AML_NOTSERIALIZED); + aml_append(method, aml_create_dword_field(aml_arg(3), aml_int(0), "CDW1")); + + /* match UUID */ + if_uuid = aml_if(aml_equal( + aml_arg(0), aml_touuid("0811B06E-4A27-44F9-8D60-3CBBC22E7B48"))); + + aml_append(if_uuid, aml_create_dword_field(aml_arg(3), aml_int(4), "CDW2")); + aml_append(if_uuid, aml_store(aml_name("CDW2"), a_cdw2)); + + /* check unknown revision in arg(1) */ + if_rev = aml_if(aml_lnot(aml_equal(aml_arg(1), aml_int(1)))); + /* set revision error bits, DWORD1 Bit[3] */ + aml_append(if_rev, aml_or(a_cdw1, aml_int(0x08), a_cdw1)); + aml_append(if_uuid, if_rev); + + /* + * check support for vCPU hotplug type(=enabled) platform-wide capability + * in DWORD2 as sepcified in the below ACPI Specification ECR, + * # https://bugzilla.tianocore.org/show_bug.cgi?id=4481 + */ + if (vms->acpi_dev) { + aml_append(if_uuid, aml_and(a_cdw2, aml_int(0x800000), a_cdw2)); + /* check if OSPM specified hotplug capability bits were masked */ + if_caps_masked = aml_if(aml_lnot(aml_equal(aml_name("CDW2"), a_cdw2))); + aml_append(if_caps_masked, aml_or(a_cdw1, aml_int(0x10), a_cdw1)); + aml_append(if_uuid, if_caps_masked); + } + aml_append(if_uuid, aml_store(a_cdw2, aml_name("CDW2"))); + + aml_append(method, if_uuid); + else_uuid = aml_else(); + + /* set unrecognized UUID error bits, DWORD1 Bit[2] */ + aml_append(else_uuid, aml_or(a_cdw1, aml_int(4), a_cdw1)); + aml_append(method, else_uuid); + + aml_append(method, aml_return(aml_arg(3))); + aml_append(scope, method); + + return; +} + /* DSDT */ static void build_dsdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) @@ -894,6 +943,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) } else { acpi_dsdt_add_cpus(scope, vms); } + + build_virt_osc_method(scope, vms); + acpi_dsdt_add_uart(scope, &memmap[VIRT_UART], (irqmap[VIRT_UART] + ARM_SPI_BASE)); if (vmc->acpi_expose_flash) { -- 2.34.1