OvmfPkg/CpuHotplugSmm: add function for collecting CPUs with events

Add a function that collects the APIC IDs of CPUs that have just been
hot-plugged, or are about to be hot-unplugged.

Pending events are only located and never cleared; QEMU's AML needs the
firmware to leave the status bits intact in the hotplug register block.

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: <20200226221156.29589-10-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

5 files changed, 211 insertions, 6 deletions

diff --git a/OvmfPkg/CpuHotplugSmm/ApicId.h b/OvmfPkg/CpuHotplugSmm/ApicId.h
new file mode 100644
index 0000000000..3c365148ed
--- /dev/null
+++ b/OvmfPkg/CpuHotplugSmm/ApicId.h
@@ -0,0 +1,23 @@
+/** @file

+  Type and macro definitions for representing and printing APIC IDs, compatibly

+  with the LocalApicLib and PrintLib classes, respectively.

+

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

+

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

+**/

+

+#ifndef APIC_ID_H_

+#define APIC_ID_H_

+

+//

+// The type that LocalApicLib represents an APIC ID with.

+//

+typedef UINT32 APIC_ID;

+

+//

+// The PrintLib conversion specification for formatting an APIC_ID.

+//

+#define FMT_APIC_ID "0x%08x"

+

+#endif // APIC_ID_H_

diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf b/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf
index ac4ca4c1f4..ab690a9e5e 100644
--- a/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf
+++ b/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf
@@ -22,6 +22,7 @@
 #

 

 [Sources]

+  ApicId.h

   CpuHotplug.c

   QemuCpuhp.c

   QemuCpuhp.h

diff --git a/OvmfPkg/CpuHotplugSmm/QemuCpuhp.c b/OvmfPkg/CpuHotplugSmm/QemuCpuhp.c
index 31e46f5193..8d4a6693c8 100644
--- a/OvmfPkg/CpuHotplugSmm/QemuCpuhp.c
+++ b/OvmfPkg/CpuHotplugSmm/QemuCpuhp.c
@@ -1,8 +1,8 @@
 /** @file

-  Simple wrapper functions that access QEMU's modern CPU hotplug register

-  block.

+  Simple wrapper functions and utility functions that access QEMU's modern CPU

+  hotplug register block.

 

-  These functions thinly wrap some of the registers described in

+  These functions manipulate some of the registers described in

   "docs/specs/acpi_cpu_hotplug.txt" in the QEMU source. IO Ports are accessed

   via EFI_MM_CPU_IO_PROTOCOL. If a protocol call fails, these functions don't

   return.

@@ -134,3 +134,168 @@ QemuCpuhpWriteCommand (
     CpuDeadLoop ();

   }

 }

+

+/**

+  Collect the APIC IDs of

+  - the CPUs that have been hot-plugged,

+  - the CPUs that are about to be hot-unplugged.

+

+  This function only scans for events -- it does not modify them -- in the

+  hotplug registers.

+

+  On error, the contents of the output parameters are undefined.

+

+  @param[in] MmCpuIo           The EFI_MM_CPU_IO_PROTOCOL instance for

+                               accessing IO Ports.

+

+  @param[in] PossibleCpuCount  The number of possible CPUs in the system. Must

+                               be positive.

+

+  @param[in] ApicIdCount       The number of elements each one of the

+                               PluggedApicIds and ToUnplugApicIds arrays can

+                               accommodate. Must be positive.

+

+  @param[out] PluggedApicIds   The APIC IDs of the CPUs that have been

+                               hot-plugged.

+

+  @param[out] PluggedCount     The number of filled-in APIC IDs in

+                               PluggedApicIds.

+

+  @param[out] ToUnplugApicIds  The APIC IDs of the CPUs that are about to be

+                               hot-unplugged.

+

+  @param[out] ToUnplugCount    The number of filled-in APIC IDs in

+                               ToUnplugApicIds.

+

+  @retval EFI_INVALID_PARAMETER  PossibleCpuCount is zero, or ApicIdCount is

+                                 zero.

+

+  @retval EFI_PROTOCOL_ERROR     Invalid bitmap detected in the

+                                 QEMU_CPUHP_R_CPU_STAT register.

+

+  @retval EFI_BUFFER_TOO_SMALL   There was an attempt to place more than

+                                 ApicIdCount APIC IDs into one of the

+                                 PluggedApicIds and ToUnplugApicIds arrays.

+

+  @retval EFI_SUCCESS            Output parameters have been set successfully.

+**/

+EFI_STATUS

+QemuCpuhpCollectApicIds (

+  IN  CONST EFI_MM_CPU_IO_PROTOCOL *MmCpuIo,

+  IN  UINT32                       PossibleCpuCount,

+  IN  UINT32                       ApicIdCount,

+  OUT APIC_ID                      *PluggedApicIds,

+  OUT UINT32                       *PluggedCount,

+  OUT APIC_ID                      *ToUnplugApicIds,

+  OUT UINT32                       *ToUnplugCount

+  )

+{

+  UINT32 CurrentSelector;

+

+  if (PossibleCpuCount == 0 || ApicIdCount == 0) {

+    return EFI_INVALID_PARAMETER;

+  }

+

+  *PluggedCount = 0;

+  *ToUnplugCount = 0;

+

+  CurrentSelector = 0;

+  do {

+    UINT32  PendingSelector;

+    UINT8   CpuStatus;

+    APIC_ID *ExtendIds;

+    UINT32  *ExtendCount;

+    APIC_ID NewApicId;

+

+    //

+    // Write CurrentSelector (which is valid) to the CPU selector register.

+    // Consequences:

+    //

+    // - Other register accesses will be permitted.

+    //

+    // - The QEMU_CPUHP_CMD_GET_PENDING command will start scanning for a CPU

+    //   with pending events at CurrentSelector (inclusive).

+    //

+    QemuCpuhpWriteCpuSelector (MmCpuIo, CurrentSelector);

+    //

+    // Write the QEMU_CPUHP_CMD_GET_PENDING command. Consequences

+    // (independently of each other):

+    //

+    // - If there is a CPU with pending events, starting at CurrentSelector

+    //   (inclusive), the CPU selector will be updated to that CPU. Note that

+    //   the scanning in QEMU may wrap around, because we must never clear the

+    //   event bits.

+    //

+    // - The QEMU_CPUHP_RW_CMD_DATA register will return the (possibly updated)

+    //   CPU selector value.

+    //

+    QemuCpuhpWriteCommand (MmCpuIo, QEMU_CPUHP_CMD_GET_PENDING);

+    PendingSelector = QemuCpuhpReadCommandData (MmCpuIo);

+    if (PendingSelector < CurrentSelector) {

+      DEBUG ((DEBUG_VERBOSE, "%a: CurrentSelector=%u PendingSelector=%u: "

+        "wrap-around\n", __FUNCTION__, CurrentSelector, PendingSelector));

+      break;

+    }

+    CurrentSelector = PendingSelector;

+

+    //

+    // Check the known status / event bits for the currently selected CPU.

+    //

+    CpuStatus = QemuCpuhpReadCpuStatus (MmCpuIo);

+    if ((CpuStatus & QEMU_CPUHP_STAT_INSERT) != 0) {

+      //

+      // The "insert" event guarantees the "enabled" status; plus it excludes

+      // the "remove" event.

+      //

+      if ((CpuStatus & QEMU_CPUHP_STAT_ENABLED) == 0 ||

+          (CpuStatus & QEMU_CPUHP_STAT_REMOVE) != 0) {

+        DEBUG ((DEBUG_ERROR, "%a: CurrentSelector=%u CpuStatus=0x%x: "

+          "inconsistent CPU status\n", __FUNCTION__, CurrentSelector,

+          CpuStatus));

+        return EFI_PROTOCOL_ERROR;

+      }

+

+      DEBUG ((DEBUG_VERBOSE, "%a: CurrentSelector=%u: insert\n", __FUNCTION__,

+        CurrentSelector));

+

+      ExtendIds   = PluggedApicIds;

+      ExtendCount = PluggedCount;

+    } else if ((CpuStatus & QEMU_CPUHP_STAT_REMOVE) != 0) {

+      DEBUG ((DEBUG_VERBOSE, "%a: CurrentSelector=%u: remove\n", __FUNCTION__,

+        CurrentSelector));

+

+      ExtendIds   = ToUnplugApicIds;

+      ExtendCount = ToUnplugCount;

+    } else {

+      DEBUG ((DEBUG_VERBOSE, "%a: CurrentSelector=%u: no event\n",

+        __FUNCTION__, CurrentSelector));

+      break;

+    }

+

+    //

+    // Save the APIC ID of the CPU with the pending event, to the corresponding

+    // APIC ID array.

+    //

+    if (*ExtendCount == ApicIdCount) {

+      DEBUG ((DEBUG_ERROR, "%a: APIC ID array too small\n", __FUNCTION__));

+      return EFI_BUFFER_TOO_SMALL;

+    }

+    QemuCpuhpWriteCommand (MmCpuIo, QEMU_CPUHP_CMD_GET_ARCH_ID);

+    NewApicId = QemuCpuhpReadCommandData (MmCpuIo);

+    DEBUG ((DEBUG_VERBOSE, "%a: ApicId=" FMT_APIC_ID "\n", __FUNCTION__,

+      NewApicId));

+    ExtendIds[(*ExtendCount)++] = NewApicId;

+

+    //

+    // We've processed the CPU with (known) pending events, but we must never

+    // clear events. Therefore we need to advance past this CPU manually;

+    // otherwise, QEMU_CPUHP_CMD_GET_PENDING would stick to the currently

+    // selected CPU.

+    //

+    CurrentSelector++;

+  } while (CurrentSelector < PossibleCpuCount);

+

+  DEBUG ((DEBUG_VERBOSE, "%a: PluggedCount=%u ToUnplugCount=%u\n",

+    __FUNCTION__, *PluggedCount, *ToUnplugCount));

+  return EFI_SUCCESS;

+}

diff --git a/OvmfPkg/CpuHotplugSmm/QemuCpuhp.h b/OvmfPkg/CpuHotplugSmm/QemuCpuhp.h
index 82f88f0b73..8adaa0ad91 100644
--- a/OvmfPkg/CpuHotplugSmm/QemuCpuhp.h
+++ b/OvmfPkg/CpuHotplugSmm/QemuCpuhp.h
@@ -1,8 +1,8 @@
 /** @file

-  Simple wrapper functions that access QEMU's modern CPU hotplug register

-  block.

+  Simple wrapper functions and utility functions that access QEMU's modern CPU

+  hotplug register block.

 

-  These functions thinly wrap some of the registers described in

+  These functions manipulate some of the registers described in

   "docs/specs/acpi_cpu_hotplug.txt" in the QEMU source. IO Ports are accessed

   via EFI_MM_CPU_IO_PROTOCOL. If a protocol call fails, these functions don't

   return.

@@ -16,6 +16,9 @@
 #define QEMU_CPUHP_H_

 

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

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

+

+#include "ApicId.h"            // APIC_ID

 

 UINT32

 QemuCpuhpReadCommandData2 (

@@ -44,4 +47,15 @@ QemuCpuhpWriteCommand (
   IN UINT8                        Command

   );

 

+EFI_STATUS

+QemuCpuhpCollectApicIds (

+  IN  CONST EFI_MM_CPU_IO_PROTOCOL *MmCpuIo,

+  IN  UINT32                       PossibleCpuCount,

+  IN  UINT32                       ApicIdCount,

+  OUT APIC_ID                      *PluggedApicIds,

+  OUT UINT32                       *PluggedCount,

+  OUT APIC_ID                      *ToUnplugApicIds,

+  OUT UINT32                       *ToUnplugCount

+  );

+

 #endif // QEMU_CPUHP_H_

diff --git a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h b/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
index 3d01363350..a34a6d3fae 100644
--- a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
+++ b/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
@@ -32,6 +32,8 @@
 

 #define QEMU_CPUHP_R_CPU_STAT                0x4

 #define QEMU_CPUHP_STAT_ENABLED                BIT0

+#define QEMU_CPUHP_STAT_INSERT                 BIT1

+#define QEMU_CPUHP_STAT_REMOVE                 BIT2

 

 #define QEMU_CPUHP_RW_CMD_DATA               0x8