diff options
| -rw-r--r-- | OvmfPkg/CpuHotplugSmm/CpuHotplug.c | 154 | ||||
| -rw-r--r-- | OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf | 2 |
2 files changed, 148 insertions, 8 deletions
diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c index 59f000e..2eeb456 100644 --- a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c +++ b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c @@ -10,10 +10,12 @@ #include <IndustryStandard/Q35MchIch9.h> // ICH9_APM_CNT
#include <IndustryStandard/QemuCpuHotplug.h> // QEMU_CPUHP_CMD_GET_PENDING
#include <Library/BaseLib.h> // CpuDeadLoop()
+#include <Library/CpuLib.h> // CpuSleep()
#include <Library/DebugLib.h> // ASSERT()
#include <Library/MmServicesTableLib.h> // gMmst
#include <Library/PcdLib.h> // PcdGetBool()
#include <Library/SafeIntLib.h> // SafeUintnSub()
+#include <Pcd/CpuHotEjectData.h> // CPU_HOT_EJECT_DATA
#include <Protocol/MmCpuIo.h> // EFI_MM_CPU_IO_PROTOCOL
#include <Protocol/SmmCpuService.h> // EFI_SMM_CPU_SERVICE_PROTOCOL
#include <Uefi/UefiBaseType.h> // EFI_STATUS
@@ -32,11 +34,12 @@ STATIC EFI_MM_CPU_IO_PROTOCOL *mMmCpuIo; //
STATIC EFI_SMM_CPU_SERVICE_PROTOCOL *mMmCpuService;
//
-// This structure is a communication side-channel between the
+// These structures serve as communication side-channels between the
// EFI_SMM_CPU_SERVICE_PROTOCOL consumer (i.e., this driver) and provider
// (i.e., PiSmmCpuDxeSmm).
//
STATIC CPU_HOT_PLUG_DATA *mCpuHotPlugData;
+STATIC CPU_HOT_EJECT_DATA *mCpuHotEjectData;
//
// SMRAM arrays for fetching the APIC IDs of processors with pending events (of
// known event types), for the time of just one MMI.
@@ -190,18 +193,71 @@ RevokeNewSlot: }
/**
+ CPU Hot-eject handler, called from SmmCpuFeaturesRendezvousExit()
+ on each CPU at exit from SMM.
+
+ If, the executing CPU is not being ejected, nothing to be done.
+ If, the executing CPU is being ejected, wait in a halted loop
+ until ejected.
+
+ @param[in] ProcessorNum ProcessorNum denotes the CPU exiting SMM,
+ and will be used as an index into
+ CPU_HOT_EJECT_DATA->QemuSelectorMap. It is
+ identical to the processor handle number in
+ EFI_SMM_CPU_SERVICE_PROTOCOL.
+**/
+VOID
+EFIAPI
+EjectCpu (
+ IN UINTN ProcessorNum
+ )
+{
+ UINT64 QemuSelector;
+
+ QemuSelector = mCpuHotEjectData->QemuSelectorMap[ProcessorNum];
+ if (QemuSelector == CPU_EJECT_QEMU_SELECTOR_INVALID) {
+ return;
+ }
+
+ //
+ // APs being unplugged get here from SmmCpuFeaturesRendezvousExit()
+ // after having been cleared to exit the SMI and so have no SMM
+ // processing remaining.
+ //
+ // Keep them penned here until the BSP tells QEMU to eject them.
+ //
+ for (;;) {
+ DisableInterrupts ();
+ CpuSleep ();
+ }
+}
+
+/**
Process to be hot-unplugged CPUs, per QemuCpuhpCollectApicIds().
For each such CPU, report the CPU to PiSmmCpuDxeSmm via
- EFI_SMM_CPU_SERVICE_PROTOCOL. If the to be hot-unplugged CPU is
- unknown, skip it silently.
+ EFI_SMM_CPU_SERVICE_PROTOCOL and stash the QEMU Cpu Selectors for later
+ ejection. If the to be hot-unplugged CPU is unknown, skip it silently.
+
+ Additonally, if we do stash any Cpu Selectors, also install a CPU eject
+ handler which would handle the ejection.
@param[in] ToUnplugApicIds The APIC IDs of the CPUs that are about to be
hot-unplugged.
+ @param[in] ToUnplugSelectors The QEMU Selectors of the CPUs that are about to
+ be hot-unplugged.
+
@param[in] ToUnplugCount The number of filled-in APIC IDs in
ToUnplugApicIds.
+ @retval EFI_ALREADY_STARTED For the ProcessorNum that
+ EFI_SMM_CPU_SERVICE_PROTOCOL had assigned to
+ one of the APIC IDs in ToUnplugApicIds,
+ mCpuHotEjectData->QemuSelectorMap already has
+ the QemuSelector value stashed. (This should
+ never happen.)
+
@retval EFI_SUCCESS Known APIC IDs have been removed from SMM data
structures.
@@ -212,23 +268,36 @@ STATIC EFI_STATUS
UnplugCpus (
IN APIC_ID *ToUnplugApicIds,
+ IN UINT32 *ToUnplugSelectors,
IN UINT32 ToUnplugCount
)
{
EFI_STATUS Status;
UINT32 ToUnplugIdx;
+ UINT32 EjectCount;
UINTN ProcessorNum;
ToUnplugIdx = 0;
+ EjectCount = 0;
while (ToUnplugIdx < ToUnplugCount) {
APIC_ID RemoveApicId;
+ UINT32 QemuSelector;
RemoveApicId = ToUnplugApicIds[ToUnplugIdx];
+ QemuSelector = ToUnplugSelectors[ToUnplugIdx];
//
- // mCpuHotPlugData->ApicId maps ProcessorNum -> ApicId. Use it to find
- // the ProcessorNum for the APIC ID to be removed.
+ // mCpuHotPlugData->ApicId maps ProcessorNum -> ApicId. Use RemoveApicId
+ // to find the corresponding ProcessorNum for the CPU to be removed.
//
+ // With this we can establish a 3 way mapping:
+ // APIC_ID -- ProcessorNum -- QemuSelector
+ //
+ // We stash the ProcessorNum -> QemuSelector mapping so it can later be
+ // used for CPU hot-eject in SmmCpuFeaturesRendezvousExit() context (where
+ // we only have ProcessorNum available.)
+ //
+
for (ProcessorNum = 0;
ProcessorNum < mCpuHotPlugData->ArrayLength;
ProcessorNum++) {
@@ -257,11 +326,62 @@ UnplugCpus ( return Status;
}
+ if (mCpuHotEjectData->QemuSelectorMap[ProcessorNum] !=
+ CPU_EJECT_QEMU_SELECTOR_INVALID) {
+ //
+ // mCpuHotEjectData->QemuSelectorMap[ProcessorNum] is set to
+ // CPU_EJECT_QEMU_SELECTOR_INVALID when mCpuHotEjectData->QemuSelectorMap
+ // is allocated, and once the subject processsor is ejected.
+ //
+ // Additionally, mMmCpuService->RemoveProcessor(ProcessorNum) invalidates
+ // mCpuHotPlugData->ApicId[ProcessorNum], so a given ProcessorNum can
+ // never match more than one APIC ID -- nor, by transitivity, designate
+ // more than one QemuSelector -- in a single invocation of UnplugCpus().
+ //
+ DEBUG ((DEBUG_ERROR, "%a: ProcessorNum %Lu maps to QemuSelector %Lu, "
+ "cannot also map to %u\n", __FUNCTION__, (UINT64)ProcessorNum,
+ mCpuHotEjectData->QemuSelectorMap[ProcessorNum], QemuSelector));
+
+ return EFI_ALREADY_STARTED;
+ }
+
+ //
+ // Stash the QemuSelector so we can do the actual ejection later.
+ //
+ mCpuHotEjectData->QemuSelectorMap[ProcessorNum] = (UINT64)QemuSelector;
+
+ DEBUG ((DEBUG_INFO, "%a: Started hot-unplug on ProcessorNum %Lu, APIC ID "
+ FMT_APIC_ID ", QemuSelector %u\n", __FUNCTION__, (UINT64)ProcessorNum,
+ RemoveApicId, QemuSelector));
+
+ EjectCount++;
ToUnplugIdx++;
}
+ if (EjectCount != 0) {
+ //
+ // We have processors to be ejected; install the handler.
+ //
+ mCpuHotEjectData->Handler = EjectCpu;
+
+ //
+ // The BSP and APs load mCpuHotEjectData->Handler, and
+ // mCpuHotEjectData->QemuSelectorMap[] in SmmCpuFeaturesRendezvousExit()
+ // and EjectCpu().
+ //
+ // The comment in SmmCpuFeaturesRendezvousExit() details how we use
+ // the AllCpusInSync control-dependency to ensure that any loads are
+ // ordered-after the stores above.
+ //
+ // Ensure that the stores above are ordered-before the AllCpusInSync store
+ // by using a MemoryFence() with release semantics.
+ //
+ MemoryFence ();
+ }
+
//
- // We've removed this set of APIC IDs from SMM data structures.
+ // We've removed this set of APIC IDs from SMM data structures and
+ // have installed an ejection handler if needed.
//
return EFI_SUCCESS;
}
@@ -389,7 +509,7 @@ CpuHotplugMmi ( }
if (ToUnplugCount > 0) {
- Status = UnplugCpus (mToUnplugApicIds, ToUnplugCount);
+ Status = UnplugCpus (mToUnplugApicIds, mToUnplugSelectors, ToUnplugCount);
if (EFI_ERROR (Status)) {
goto Fatal;
}
@@ -460,9 +580,14 @@ CpuHotplugEntry ( //
// Our DEPEX on EFI_SMM_CPU_SERVICE_PROTOCOL guarantees that PiSmmCpuDxeSmm
- // has pointed PcdCpuHotPlugDataAddress to CPU_HOT_PLUG_DATA in SMRAM.
+ // has pointed:
+ // - PcdCpuHotPlugDataAddress to CPU_HOT_PLUG_DATA in SMRAM,
+ // - PcdCpuHotEjectDataAddress to CPU_HOT_EJECT_DATA in SMRAM, if the
+ // possible CPU count is greater than 1.
//
mCpuHotPlugData = (VOID *)(UINTN)PcdGet64 (PcdCpuHotPlugDataAddress);
+ mCpuHotEjectData = (VOID *)(UINTN)PcdGet64 (PcdCpuHotEjectDataAddress);
+
if (mCpuHotPlugData == NULL) {
Status = EFI_NOT_FOUND;
DEBUG ((DEBUG_ERROR, "%a: CPU_HOT_PLUG_DATA: %r\n", __FUNCTION__, Status));
@@ -474,6 +599,19 @@ CpuHotplugEntry ( if (mCpuHotPlugData->ArrayLength == 1) {
return EFI_UNSUPPORTED;
}
+
+ if (mCpuHotEjectData == NULL) {
+ Status = EFI_NOT_FOUND;
+ } else if (mCpuHotPlugData->ArrayLength != mCpuHotEjectData->ArrayLength) {
+ Status = EFI_INVALID_PARAMETER;
+ } else {
+ Status = EFI_SUCCESS;
+ }
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_ERROR, "%a: CPU_HOT_EJECT_DATA: %r\n", __FUNCTION__, Status));
+ goto Fatal;
+ }
+
//
// Allocate the data structures that depend on the possible CPU count.
//
diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf b/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf index 04322b0..ebcc7e2 100644 --- a/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf +++ b/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf @@ -40,6 +40,7 @@ [LibraryClasses]
BaseLib
BaseMemoryLib
+ CpuLib
DebugLib
LocalApicLib
MmServicesTableLib
@@ -54,6 +55,7 @@ [Pcd]
gUefiCpuPkgTokenSpaceGuid.PcdCpuHotPlugDataAddress ## CONSUMES
+ gUefiOvmfPkgTokenSpaceGuid.PcdCpuHotEjectDataAddress ## CONSUMES
gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase ## CONSUMES
[FeaturePcd]
|