OvmfPkg/CpuHotplugSmm: add function for collecting CPUs with events

[mirror_edk2.git] / OvmfPkg / CpuHotplugSmm / CpuHotplug.c

/** @file\r
  Root SMI handler for VCPU hotplug SMIs.\r
\r
  Copyright (c) 2020, Red Hat, Inc.\r
\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
**/\r
\r
#include <IndustryStandard/Q35MchIch9.h>     // ICH9_APM_CNT\r
#include <IndustryStandard/QemuCpuHotplug.h> // QEMU_CPUHP_CMD_GET_PENDING\r
#include <Library/BaseLib.h>                 // CpuDeadLoop()\r
#include <Library/DebugLib.h>                // ASSERT()\r
#include <Library/MmServicesTableLib.h>      // gMmst\r
#include <Library/PcdLib.h>                  // PcdGetBool()\r
#include <Protocol/MmCpuIo.h>                // EFI_MM_CPU_IO_PROTOCOL\r
#include <Uefi/UefiBaseType.h>               // EFI_STATUS\r
\r
#include "QemuCpuhp.h"                       // QemuCpuhpWriteCpuSelector()\r
\r
//\r
// We use this protocol for accessing IO Ports.\r
//\r
STATIC EFI_MM_CPU_IO_PROTOCOL *mMmCpuIo;\r
//\r
// Represents the registration of the CPU Hotplug MMI handler.\r
//\r
STATIC EFI_HANDLE mDispatchHandle;\r
\r
\r
/**\r
  CPU Hotplug MMI handler function.\r
\r
  This is a root MMI handler.\r
\r
  @param[in] DispatchHandle      The unique handle assigned to this handler by\r
                                 EFI_MM_SYSTEM_TABLE.MmiHandlerRegister().\r
\r
  @param[in] Context             Context passed in by\r
                                 EFI_MM_SYSTEM_TABLE.MmiManage(). Due to\r
                                 CpuHotplugMmi() being a root MMI handler,\r
                                 Context is ASSERT()ed to be NULL.\r
\r
  @param[in,out] CommBuffer      Ignored, due to CpuHotplugMmi() being a root\r
                                 MMI handler.\r
\r
  @param[in,out] CommBufferSize  Ignored, due to CpuHotplugMmi() being a root\r
                                 MMI handler.\r
\r
  @retval EFI_SUCCESS                       The MMI was handled and the MMI\r
                                            source was quiesced. When returned\r
                                            by a non-root MMI handler,\r
                                            EFI_SUCCESS terminates the\r
                                            processing of MMI handlers in\r
                                            EFI_MM_SYSTEM_TABLE.MmiManage().\r
                                            For a root MMI handler (i.e., for\r
                                            the present function too),\r
                                            EFI_SUCCESS behaves identically to\r
                                            EFI_WARN_INTERRUPT_SOURCE_QUIESCED,\r
                                            as further root MMI handlers are\r
                                            going to be called by\r
                                            EFI_MM_SYSTEM_TABLE.MmiManage()\r
                                            anyway.\r
\r
  @retval EFI_WARN_INTERRUPT_SOURCE_QUIESCED  The MMI source has been quiesced,\r
                                              but other handlers should still\r
                                              be called.\r
\r
  @retval EFI_WARN_INTERRUPT_SOURCE_PENDING   The MMI source is still pending,\r
                                              and other handlers should still\r
                                              be called.\r
\r
  @retval EFI_INTERRUPT_PENDING               The MMI source could not be\r
                                              quiesced.\r
**/\r
STATIC\r
EFI_STATUS\r
EFIAPI\r
CpuHotplugMmi (\r
  IN EFI_HANDLE DispatchHandle,\r
  IN CONST VOID *Context        OPTIONAL,\r
  IN OUT VOID   *CommBuffer     OPTIONAL,\r
  IN OUT UINTN  *CommBufferSize OPTIONAL\r
  )\r
{\r
  EFI_STATUS Status;\r
  UINT8      ApmControl;\r
\r
  //\r
  // Assert that we are entering this function due to our root MMI handler\r
  // registration.\r
  //\r
  ASSERT (DispatchHandle == mDispatchHandle);\r
  //\r
  // When MmiManage() is invoked to process root MMI handlers, the caller (the\r
  // MM Core) is expected to pass in a NULL Context. MmiManage() then passes\r
  // the same NULL Context to individual handlers.\r
  //\r
  ASSERT (Context == NULL);\r
  //\r
  // Read the MMI command value from the APM Control Port, to see if this is an\r
  // MMI we should care about.\r
  //\r
  Status = mMmCpuIo->Io.Read (mMmCpuIo, MM_IO_UINT8, ICH9_APM_CNT, 1,\r
                          &ApmControl);\r
  if (EFI_ERROR (Status)) {\r
    DEBUG ((DEBUG_ERROR, "%a: failed to read ICH9_APM_CNT: %r\n", __FUNCTION__,\r
      Status));\r
    //\r
    // We couldn't even determine if the MMI was for us or not.\r
    //\r
    goto Fatal;\r
  }\r
\r
  if (ApmControl != ICH9_APM_CNT_CPU_HOTPLUG) {\r
    //\r
    // The MMI is not for us.\r
    //\r
    return EFI_WARN_INTERRUPT_SOURCE_QUIESCED;\r
  }\r
\r
  //\r
  // We've handled this MMI.\r
  //\r
  return EFI_SUCCESS;\r
\r
Fatal:\r
  ASSERT (FALSE);\r
  CpuDeadLoop ();\r
  //\r
  // We couldn't handle this MMI.\r
  //\r
  return EFI_INTERRUPT_PENDING;\r
}\r
\r
\r
//\r
// Entry point function of this driver.\r
//\r
EFI_STATUS\r
EFIAPI\r
CpuHotplugEntry (\r
  IN EFI_HANDLE       ImageHandle,\r
  IN EFI_SYSTEM_TABLE *SystemTable\r
  )\r
{\r
  EFI_STATUS Status;\r
\r
  //\r
  // This module should only be included when SMM support is required.\r
  //\r
  ASSERT (FeaturePcdGet (PcdSmmSmramRequire));\r
  //\r
  // This driver depends on the dynamically detected "SMRAM at default SMBASE"\r
  // feature.\r
  //\r
  if (!PcdGetBool (PcdQ35SmramAtDefaultSmbase)) {\r
    return EFI_UNSUPPORTED;\r
  }\r
\r
  //\r
  // Errors from here on are fatal; we cannot allow the boot to proceed if we\r
  // can't set up this driver to handle CPU hotplug.\r
  //\r
  // First, collect the protocols needed later. All of these protocols are\r
  // listed in our module DEPEX.\r
  //\r
  Status = gMmst->MmLocateProtocol (&gEfiMmCpuIoProtocolGuid,\r
                    NULL /* Registration */, (VOID **)&mMmCpuIo);\r
  if (EFI_ERROR (Status)) {\r
    DEBUG ((DEBUG_ERROR, "%a: locate MmCpuIo: %r\n", __FUNCTION__, Status));\r
    goto Fatal;\r
  }\r
\r
  //\r
  // Sanity-check the CPU hotplug interface.\r
  //\r
  // Both of the following features are part of QEMU 5.0, introduced primarily\r
  // in commit range 3e08b2b9cb64..3a61c8db9d25:\r
  //\r
  // (a) the QEMU_CPUHP_CMD_GET_ARCH_ID command of the modern CPU hotplug\r
  //     interface,\r
  //\r
  // (b) the "SMRAM at default SMBASE" feature.\r
  //\r
  // From these, (b) is restricted to 5.0+ machine type versions, while (a)\r
  // does not depend on machine type version. Because we ensured the stricter\r
  // condition (b) through PcdQ35SmramAtDefaultSmbase above, the (a)\r
  // QEMU_CPUHP_CMD_GET_ARCH_ID command must now be available too. While we\r
  // can't verify the presence of precisely that command, we can still verify\r
  // (sanity-check) that the modern interface is active, at least.\r
  //\r
  // Consult the "Typical usecases | Detecting and enabling modern CPU hotplug\r
  // interface" section in QEMU's "docs/specs/acpi_cpu_hotplug.txt", on the\r
  // following.\r
  //\r
  QemuCpuhpWriteCpuSelector (mMmCpuIo, 0);\r
  QemuCpuhpWriteCpuSelector (mMmCpuIo, 0);\r
  QemuCpuhpWriteCommand (mMmCpuIo, QEMU_CPUHP_CMD_GET_PENDING);\r
  if (QemuCpuhpReadCommandData2 (mMmCpuIo) != 0) {\r
    Status = EFI_NOT_FOUND;\r
    DEBUG ((DEBUG_ERROR, "%a: modern CPU hotplug interface: %r\n",\r
      __FUNCTION__, Status));\r
    goto Fatal;\r
  }\r
\r
  //\r
  // Register the handler for the CPU Hotplug MMI.\r
  //\r
  Status = gMmst->MmiHandlerRegister (\r
                    CpuHotplugMmi,\r
                    NULL,            // HandlerType: root MMI handler\r
                    &mDispatchHandle\r
                    );\r
  if (EFI_ERROR (Status)) {\r
    DEBUG ((DEBUG_ERROR, "%a: MmiHandlerRegister(): %r\n", __FUNCTION__,\r
      Status));\r
    goto Fatal;\r
  }\r
\r
  return EFI_SUCCESS;\r
\r
Fatal:\r
  ASSERT (FALSE);\r
  CpuDeadLoop ();\r
  return Status;\r
}\r