OvmfPkg/CpuHotplugSmm: introduce skeleton for CPU Hotplug SMM driver

Add a new SMM driver skeleton that registers a root SMI handler, and
checks if the SMI control value (written to 0xB2) indicates a CPU hotplug
SMI.

QEMU's ACPI payload will cause the OS to raise a broadcast SMI when a CPU
hotplug event occurs, namely by writing value 4 to IO Port 0xB2. In other
words, control value 4 is now allocated for this purpose; introduce the
ICH9_APM_CNT_CPU_HOTPLUG macro for it.

The standard identifiers in this driver use the new MM (Management Mode)
terminology from the PI spec, not the earlier SMM (System Management Mode)
terms.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-7-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

2 files changed, 239 insertions, 0 deletions

diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
new file mode 100644
index 0000000000..fd09403eab
--- /dev/null
+++ b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
@@ -0,0 +1,191 @@
+/** @file

+  Root SMI handler for VCPU hotplug SMIs.

+

+  Copyright (c) 2020, Red Hat, Inc.

+

+  SPDX-License-Identifier: BSD-2-Clause-Patent

+**/

+

+#include <IndustryStandard/Q35MchIch9.h>     // ICH9_APM_CNT

+#include <Library/BaseLib.h>                 // CpuDeadLoop()

+#include <Library/DebugLib.h>                // ASSERT()

+#include <Library/MmServicesTableLib.h>      // gMmst

+#include <Library/PcdLib.h>                  // PcdGetBool()

+#include <Protocol/MmCpuIo.h>                // EFI_MM_CPU_IO_PROTOCOL

+#include <Uefi/UefiBaseType.h>               // EFI_STATUS

+

+//

+// We use this protocol for accessing IO Ports.

+//

+STATIC EFI_MM_CPU_IO_PROTOCOL *mMmCpuIo;

+//

+// Represents the registration of the CPU Hotplug MMI handler.

+//

+STATIC EFI_HANDLE mDispatchHandle;

+

+

+/**

+  CPU Hotplug MMI handler function.

+

+  This is a root MMI handler.

+

+  @param[in] DispatchHandle      The unique handle assigned to this handler by

+                                 EFI_MM_SYSTEM_TABLE.MmiHandlerRegister().

+

+  @param[in] Context             Context passed in by

+                                 EFI_MM_SYSTEM_TABLE.MmiManage(). Due to

+                                 CpuHotplugMmi() being a root MMI handler,

+                                 Context is ASSERT()ed to be NULL.

+

+  @param[in,out] CommBuffer      Ignored, due to CpuHotplugMmi() being a root

+                                 MMI handler.

+

+  @param[in,out] CommBufferSize  Ignored, due to CpuHotplugMmi() being a root

+                                 MMI handler.

+

+  @retval EFI_SUCCESS                       The MMI was handled and the MMI

+                                            source was quiesced. When returned

+                                            by a non-root MMI handler,

+                                            EFI_SUCCESS terminates the

+                                            processing of MMI handlers in

+                                            EFI_MM_SYSTEM_TABLE.MmiManage().

+                                            For a root MMI handler (i.e., for

+                                            the present function too),

+                                            EFI_SUCCESS behaves identically to

+                                            EFI_WARN_INTERRUPT_SOURCE_QUIESCED,

+                                            as further root MMI handlers are

+                                            going to be called by

+                                            EFI_MM_SYSTEM_TABLE.MmiManage()

+                                            anyway.

+

+  @retval EFI_WARN_INTERRUPT_SOURCE_QUIESCED  The MMI source has been quiesced,

+                                              but other handlers should still

+                                              be called.

+

+  @retval EFI_WARN_INTERRUPT_SOURCE_PENDING   The MMI source is still pending,

+                                              and other handlers should still

+                                              be called.

+

+  @retval EFI_INTERRUPT_PENDING               The MMI source could not be

+                                              quiesced.

+**/

+STATIC

+EFI_STATUS

+EFIAPI

+CpuHotplugMmi (

+  IN EFI_HANDLE DispatchHandle,

+  IN CONST VOID *Context        OPTIONAL,

+  IN OUT VOID   *CommBuffer     OPTIONAL,

+  IN OUT UINTN  *CommBufferSize OPTIONAL

+  )

+{

+  EFI_STATUS Status;

+  UINT8      ApmControl;

+

+  //

+  // Assert that we are entering this function due to our root MMI handler

+  // registration.

+  //

+  ASSERT (DispatchHandle == mDispatchHandle);

+  //

+  // When MmiManage() is invoked to process root MMI handlers, the caller (the

+  // MM Core) is expected to pass in a NULL Context. MmiManage() then passes

+  // the same NULL Context to individual handlers.

+  //

+  ASSERT (Context == NULL);

+  //

+  // Read the MMI command value from the APM Control Port, to see if this is an

+  // MMI we should care about.

+  //

+  Status = mMmCpuIo->Io.Read (mMmCpuIo, MM_IO_UINT8, ICH9_APM_CNT, 1,

+                          &ApmControl);

+  if (EFI_ERROR (Status)) {

+    DEBUG ((DEBUG_ERROR, "%a: failed to read ICH9_APM_CNT: %r\n", __FUNCTION__,

+      Status));

+    //

+    // We couldn't even determine if the MMI was for us or not.

+    //

+    goto Fatal;

+  }

+

+  if (ApmControl != ICH9_APM_CNT_CPU_HOTPLUG) {

+    //

+    // The MMI is not for us.

+    //

+    return EFI_WARN_INTERRUPT_SOURCE_QUIESCED;

+  }

+

+  //

+  // We've handled this MMI.

+  //

+  return EFI_SUCCESS;

+

+Fatal:

+  ASSERT (FALSE);

+  CpuDeadLoop ();

+  //

+  // We couldn't handle this MMI.

+  //

+  return EFI_INTERRUPT_PENDING;

+}

+

+

+//

+// Entry point function of this driver.

+//

+EFI_STATUS

+EFIAPI

+CpuHotplugEntry (

+  IN EFI_HANDLE       ImageHandle,

+  IN EFI_SYSTEM_TABLE *SystemTable

+  )

+{

+  EFI_STATUS Status;

+

+  //

+  // This module should only be included when SMM support is required.

+  //

+  ASSERT (FeaturePcdGet (PcdSmmSmramRequire));

+  //

+  // This driver depends on the dynamically detected "SMRAM at default SMBASE"

+  // feature.

+  //

+  if (!PcdGetBool (PcdQ35SmramAtDefaultSmbase)) {

+    return EFI_UNSUPPORTED;

+  }

+

+  //

+  // Errors from here on are fatal; we cannot allow the boot to proceed if we

+  // can't set up this driver to handle CPU hotplug.

+  //

+  // First, collect the protocols needed later. All of these protocols are

+  // listed in our module DEPEX.

+  //

+  Status = gMmst->MmLocateProtocol (&gEfiMmCpuIoProtocolGuid,

+                    NULL /* Registration */, (VOID **)&mMmCpuIo);

+  if (EFI_ERROR (Status)) {

+    DEBUG ((DEBUG_ERROR, "%a: locate MmCpuIo: %r\n", __FUNCTION__, Status));

+    goto Fatal;

+  }

+

+  //

+  // Register the handler for the CPU Hotplug MMI.

+  //

+  Status = gMmst->MmiHandlerRegister (

+                    CpuHotplugMmi,

+                    NULL,            // HandlerType: root MMI handler

+                    &mDispatchHandle

+                    );

+  if (EFI_ERROR (Status)) {

+    DEBUG ((DEBUG_ERROR, "%a: MmiHandlerRegister(): %r\n", __FUNCTION__,

+      Status));

+    goto Fatal;

+  }

+

+  return EFI_SUCCESS;

+

+Fatal:

+  ASSERT (FALSE);

+  CpuDeadLoop ();

+  return Status;

+}

diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf b/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf
new file mode 100644
index 0000000000..fa70858a8d
--- /dev/null
+++ b/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf
@@ -0,0 +1,48 @@
+## @file

+# Root SMI handler for VCPU hotplug SMIs.

+#

+# Copyright (c) 2020, Red Hat, Inc.

+#

+# SPDX-License-Identifier: BSD-2-Clause-Patent

+##

+

+[Defines]

+  INF_VERSION                = 1.29

+  PI_SPECIFICATION_VERSION   = 0x00010046                            # PI-1.7.0

+  BASE_NAME                  = CpuHotplugSmm

+  FILE_GUID                  = 84EEA114-C6BE-4445-8F90-51D97863E363

+  MODULE_TYPE                = DXE_SMM_DRIVER

+  ENTRY_POINT                = CpuHotplugEntry

+

+#

+# The following information is for reference only and not required by the build

+# tools.

+#

+# VALID_ARCHITECTURES        = IA32 X64

+#

+

+[Sources]

+  CpuHotplug.c

+

+[Packages]

+  MdePkg/MdePkg.dec

+  OvmfPkg/OvmfPkg.dec

+

+[LibraryClasses]

+  BaseLib

+  DebugLib

+  MmServicesTableLib

+  PcdLib

+  UefiDriverEntryPoint

+

+[Protocols]

+  gEfiMmCpuIoProtocolGuid                                           ## CONSUMES

+

+[Pcd]

+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase             ## CONSUMES

+

+[FeaturePcd]

+  gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire                     ## CONSUMES

+

+[Depex]

+  gEfiMmCpuIoProtocolGuid