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[PATCH RFC V2 18/37] arm/virt: Make ARM vCPU *present* status ACPI *pers
From: |
Salil Mehta |
Subject: |
[PATCH RFC V2 18/37] arm/virt: Make ARM vCPU *present* status ACPI *persistent* |
Date: |
Tue, 26 Sep 2023 11:04:17 +0100 |
ARM arch does not allow CPUs presence to be changed [1] after kernel has booted.
Hence, firmware/ACPI/Qemu must ensure persistent view of the vCPUs to the Guest
kernel even when they are not present in the QoM i.e. are unplugged or are
yet-to-be-plugged
References:
[1] Check comment 5 in the bugzilla entry
Link: https://bugzilla.tianocore.org/show_bug.cgi?id=4481#c5
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
cpus-common.c | 6 ++++++
hw/arm/virt.c | 7 +++++++
include/hw/core/cpu.h | 20 ++++++++++++++++++++
3 files changed, 33 insertions(+)
diff --git a/cpus-common.c b/cpus-common.c
index 24c04199a1..d64aa63b19 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -128,6 +128,12 @@ bool qemu_enabled_cpu(CPUState *cpu)
return cpu && !cpu->disabled;
}
+bool qemu_persistent_cpu(CPUState *cpu)
+{
+ /* cpu state can be faked to the guest via acpi */
+ return cpu->acpi_persistent;
+}
+
uint64_t qemu_get_cpu_archid(int cpu_index)
{
MachineState *ms = MACHINE(qdev_get_machine());
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index cbb6199ec6..f1bee569d5 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -3006,6 +3006,13 @@ static void virt_cpu_pre_plug(HotplugHandler
*hotplug_dev, DeviceState *dev,
return;
}
virt_cpu_set_properties(OBJECT(cs), cpu_slot, errp);
+
+ /*
+ * To give persistent presence view of vCPUs to the guest, ACPI might need
+ * to fake the presence of the vCPUs to the guest but keep them disabled.
+ * This shall be used during the init of ACPI Hotplug state and hot-unplug
+ */
+ cs->acpi_persistent = true;
}
static void virt_cpu_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index b2201a98ee..dab572c9bd 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -425,6 +425,13 @@ struct CPUState {
* By default every CPUState is enabled as of now across all archs.
*/
bool disabled;
+ /*
+ * On certain architectures, to give persistent view of the 'presence' of
+ * vCPUs to the guest, ACPI might need to fake the 'presence' of the vCPUs
+ * but keep them ACPI disabled to the guest. This is done by returning
+ * _STA.PRES=True and _STA.Ena=False for the unplugged vCPUs in QEMU QoM.
+ */
+ bool acpi_persistent;
/* TODO Move common fields from CPUArchState here. */
int cpu_index;
int cluster_index;
@@ -814,6 +821,19 @@ bool qemu_present_cpu(CPUState *cpu);
*/
bool qemu_enabled_cpu(CPUState *cpu);
+/**
+ * qemu_persistent_cpu:
+ * @cpu: The vCPU to check
+ *
+ * Checks if the vCPU state should always be reflected as *present* via ACPI
+ * to the Guest. By default, this is False on all architectures and has to be
+ * explicity set during initialization.
+ *
+ * Returns: True if it is ACPI 'persistent' CPU
+ *
+ */
+bool qemu_persistent_cpu(CPUState *cpu);
+
/**
* qemu_get_cpu_archid:
* @cpu_index: possible vCPU for which arch-id needs to be retreived
--
2.34.1
- [PATCH RFC V2 12/37] hw/acpi: Use qemu_present_cpu() API in ACPI CPU hotplug init, (continued)
- [PATCH RFC V2 12/37] hw/acpi: Use qemu_present_cpu() API in ACPI CPU hotplug init, Salil Mehta, 2023/09/26
- [PATCH RFC V2 14/37] arm/virt: Add cpu hotplug events to GED during creation, Salil Mehta, 2023/09/26
- [PATCH RFC V2 15/37] arm/virt: Create GED dev before *disabled* CPU Objs are destroyed, Salil Mehta, 2023/09/26
- [PATCH RFC V2 16/37] hw/acpi: Update CPUs AML with cpu-(ctrl)dev change, Salil Mehta, 2023/09/26
- [PATCH RFC V2 17/37] arm/virt/acpi: Build CPUs AML with CPU Hotplug support, Salil Mehta, 2023/09/26
- [PATCH RFC V2 18/37] arm/virt: Make ARM vCPU *present* status ACPI *persistent*,
Salil Mehta <=
- [PATCH RFC V2 19/37] hw/acpi: ACPI/AML Changes to reflect the correct _STA.{PRES, ENA} Bits to Guest, Salil Mehta, 2023/09/26
- [PATCH RFC V2 20/37] hw/acpi: Update GED _EVT method AML with cpu scan, Salil Mehta, 2023/09/26
- [PATCH RFC V2 21/37] hw/arm: MADT Tbl change to size the guest with possible vCPUs, Salil Mehta, 2023/09/26
- [PATCH RFC V2 22/37] hw/acpi: Make _MAT method optional, Salil Mehta, 2023/09/26
- [PATCH RFC V2 23/37] arm/virt: Release objects for *disabled* possible vCPUs after init, Salil Mehta, 2023/09/26