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| author | Ankur Arora <ankur.a.arora@oracle.com> | 2021-03-11 22:26:53 -0800 |
|---|---|---|
| committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2021-03-16 13:21:46 +0000 |
| commit | af9c77e151fa35fa199cbb306167277425515e3b (patch) | |
| tree | 4a2152b3f909a17875ea8ea858bcc9a5fc34d740 /OvmfPkg/Library | |
| parent | b6d5996706ddb6082e3ea8de79849bfecf2aaa15 (diff) | |
| download | edk2-af9c77e151fa35fa199cbb306167277425515e3b.tar.gz edk2-af9c77e151fa35fa199cbb306167277425515e3b.tar.bz2 edk2-af9c77e151fa35fa199cbb306167277425515e3b.zip | |
OvmfPkg/SmmCpuFeaturesLib: call CPU hot-eject handler
Call the CPU hot-eject handler if one is installed. The condition for
installation is (PcdCpuMaxLogicalProcessorNumber > 1), and there's
a hot-unplug request.
The handler is called from SmmCpuFeaturesRendezvousExit(), which is
in-turn called at the tail-end of SmiRendezvous() after the BSP has
signalled an SMI exit via the "AllCpusInSync" loop.
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: <20210312062656.2477515-8-ankur.a.arora@oracle.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Diffstat (limited to 'OvmfPkg/Library')
| -rw-r--r-- | OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c index 5c025bc717..fdf2380974 100644 --- a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c +++ b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c @@ -452,6 +452,40 @@ SmmCpuFeaturesRendezvousExit ( IN UINTN CpuIndex
)
{
+ //
+ // We only call the Handler if CPU hot-eject is enabled
+ // (PcdCpuMaxLogicalProcessorNumber > 1), and hot-eject is needed
+ // in this SMI exit (otherwise mCpuHotEjectData->Handler is not armed.)
+ //
+
+ if (mCpuHotEjectData != NULL) {
+ CPU_HOT_EJECT_HANDLER Handler;
+
+ //
+ // As the comment above mentions, mCpuHotEjectData->Handler might be
+ // written to on the BSP as part of handling of the CPU-ejection.
+ //
+ // We know that any initial assignment to mCpuHotEjectData->Handler
+ // (on the BSP, in the CpuHotplugMmi() context) is ordered-before the
+ // load below, since it is guaranteed to happen before the
+ // control-dependency of the BSP's SMI exit signal -- by way of a store
+ // to AllCpusInSync (on the BSP, in BspHandler()) and the corresponding
+ // AllCpusInSync loop (on the APs, in SmiRendezvous()) which depends on
+ // that store.
+ //
+ // This guarantees that these pieces of code can never execute
+ // simultaneously. In addition, we ensure that the following load is
+ // ordered-after the AllCpusInSync loop by using a MemoryFence() with
+ // acquire semantics.
+ //
+ MemoryFence();
+
+ Handler = mCpuHotEjectData->Handler;
+
+ if (Handler != NULL) {
+ Handler (CpuIndex);
+ }
+ }
}
/**
|