[PATCH v2 5/8] x86: acpi: let the firmware handle pending "CPU remove" events in SMM

[Igor Mammedov]

if firmware and QEMU negotiated CPU hotunplug support, generate
_EJ0 method so that it will mark CPU for removal by firmware and
pass control to it by triggering SMI.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
v2:
  - drop reserved bit before CPU_FW_EJECT_EVENT field, otherwise
    AML will point to bit #5 instead on intended bit #4
    (Ankur Arora <ankur.a.arora@oracle.com>)
---
 include/hw/acpi/cpu.h |  1 +
 hw/acpi/cpu.c         | 14 ++++++++++++--
 hw/i386/acpi-build.c  |  1 +
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/hw/acpi/cpu.h b/include/hw/acpi/cpu.h
index d71edde456..999caaf510 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 1293204438..6350caa765 100644
--- a/hw/acpi/cpu.c
+++ b/hw/acpi/cpu.c
@@ -342,6 +342,7 @@ 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,
@@ -394,7 +395,9 @@ 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));
+        /* 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));
         aml_append(field, aml_named_field(CPU_COMMAND, 8));
         aml_append(cpu_ctrl_dev, field);
 
@@ -429,6 +432,7 @@ 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")));
@@ -471,7 +475,13 @@ 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 9036e5594c..475e76f514 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");
-- 
2.27.0