summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorAnkur Arora <ankur.a.arora@oracle.com>2021-03-11 22:26:54 -0800
committermergify[bot] <37929162+mergify[bot]@users.noreply.github.com>2021-03-16 13:21:46 +0000
commit30c69d2cfa63b4b418e01e3edd53d615fa34640d (patch)
tree3cc139340bf4187017a5730be39aa31c41778a64
parentaf9c77e151fa35fa199cbb306167277425515e3b (diff)
downloadedk2-30c69d2cfa63b4b418e01e3edd53d615fa34640d.tar.gz
edk2-30c69d2cfa63b4b418e01e3edd53d615fa34640d.tar.bz2
edk2-30c69d2cfa63b4b418e01e3edd53d615fa34640d.zip
OvmfPkg/CpuHotplugSmm: add EjectCpu()
Add EjectCpu(), which handles the CPU ejection, and provides a holding area for said CPUs. It is called via SmmCpuFeaturesRendezvousExit(), at the tail end of the SMI handling. Also UnplugCpus() now stashes QEMU Selectors of CPUs which need to be ejected in CPU_HOT_EJECT_DATA.QemuSelectorMap. This is used by EjectCpu() to identify CPUs marked for ejection. Cc: Laszlo Ersek <lersek@redhat.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Aaron Young <aaron.young@oracle.com> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132 Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> Message-Id: <20210312062656.2477515-9-ankur.a.arora@oracle.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
-rw-r--r--OvmfPkg/CpuHotplugSmm/CpuHotplug.c154
-rw-r--r--OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf2
2 files changed, 148 insertions, 8 deletions
diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
index 59f000eb78..2eeb4567a2 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 04322b0d78..ebcc7e2ac6 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]