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OvmfPkg/SmmControl2Dxe: negotiate ICH9_LPC_SMI_F_CPU_HOTPLUG 

The ICH9_LPC_SMI_F_BROADCAST and ICH9_LPC_SMI_F_CPU_HOTPLUG feature flags
cause QEMU to behave as follows:

  BROADCAST  CPU_HOTPLUG  use case / behavior
  ---------  -----------  ------------------------------------------------
  clear      clear        OVMF built without SMM_REQUIRE; or very old OVMF
                          (from before commit a316d7ac91 / 2017-02-07).
                          QEMU permits CPU hotplug operations, and does
                          not cause the OS to inject an SMI upon hotplug.
                          Firmware is not expected to be aware of hotplug
                          events.

  clear      set          Invalid feature set; QEMU rejects the feature
                          negotiation.

  set        clear        OVMF after a316d7ac91 / 2017-02-07, built with
                          SMM_REQUIRE, but no support for CPU hotplug.
                          QEMU gracefully refuses hotplug operations.

  set        set          OVMF after a316d7ac91 / 2017-02-07, built with
                          SMM_REQUIRE, and supporting CPU hotplug. QEMU
                          permits CPU hotplug operations, and causes the
                          OS to inject an SMI upon hotplug. Firmware is
                          expected to deal with hotplug events.

Negotiate ICH9_LPC_SMI_F_CPU_HOTPLUG -- but only if SEV is disabled, as
OvmfPkg/CpuHotplugSmm can't deal with SEV yet.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200714184305.9814-1-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
This commit is contained in:
Laszlo Ersek 2020-07-14 20:43:05 +02:00 committed by mergify[bot]
parent 4535fc312b
commit 5ba203b54e
2 changed files with 25 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
OvmfPkg/SmmControl2Dxe/SmiFeatures.c
View File

@ -9,6 +9,7 @@
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/MemEncryptSevLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/PcdLib.h>
#include <Library/QemuFwCfgLib.h>
@ -21,6 +22,12 @@
// "etc/smi/supported-features" and "etc/smi/requested-features" fw_cfg files.
//
#define ICH9_LPC_SMI_F_BROADCAST BIT0
//
// The following bit value stands for "enable CPU hotplug, and inject an SMI
// with control value ICH9_APM_CNT_CPU_HOTPLUG upon hotplug", in the
// "etc/smi/supported-features" and "etc/smi/requested-features" fw_cfg files.
//
#define ICH9_LPC_SMI_F_CPU_HOTPLUG BIT1
//
// Provides a scratch buffer (allocated in EfiReservedMemoryType type memory)
@ -67,6 +74,7 @@ NegotiateSmiFeatures (
UINTN SupportedFeaturesSize;
UINTN RequestedFeaturesSize;
UINTN FeaturesOkSize;
UINT64 RequestedFeaturesMask;
//
// Look up the fw_cfg files used for feature negotiation. The selector keys
@ -104,9 +112,16 @@ NegotiateSmiFeatures (
QemuFwCfgReadBytes (sizeof mSmiFeatures, &mSmiFeatures);
//
// We want broadcast SMI and nothing else.
// We want broadcast SMI, SMI on CPU hotplug, and nothing else.
//
mSmiFeatures &= ICH9_LPC_SMI_F_BROADCAST;
RequestedFeaturesMask = ICH9_LPC_SMI_F_BROADCAST;
if (!MemEncryptSevIsEnabled ()) {
//
// For now, we only support hotplug with SEV disabled.
//
RequestedFeaturesMask |= ICH9_LPC_SMI_F_CPU_HOTPLUG;
}
mSmiFeatures &= RequestedFeaturesMask;
QemuFwCfgSelectItem (mRequestedFeaturesItem);
QemuFwCfgWriteBytes (sizeof mSmiFeatures, &mSmiFeatures);
@ -144,6 +159,13 @@ NegotiateSmiFeatures (
DEBUG ((DEBUG_INFO, "%a: using SMI broadcast\n", __FUNCTION__));
}
if ((mSmiFeatures & ICH9_LPC_SMI_F_CPU_HOTPLUG) == 0) {
DEBUG ((DEBUG_INFO, "%a: CPU hotplug not negotiated\n", __FUNCTION__));
} else {
DEBUG ((DEBUG_INFO, "%a: CPU hotplug with SMI negotiated\n",
__FUNCTION__));
}
//
// Negotiation successful (although we may not have gotten the optimal
// feature set).

1
OvmfPkg/SmmControl2Dxe/SmmControl2Dxe.inf
View File

@ -46,6 +46,7 @@
BaseLib
DebugLib
IoLib
MemEncryptSevLib
MemoryAllocationLib
PcdLib
PciLib