Thanks Laszlo. Both are good comments. I will follow in next version
Thanks
Zhiguang
> -----Original Message-----
> From: Laszlo Ersek <ler...@redhat.com>
> Sent: Wednesday, February 28, 2024 4:45 PM
> To: devel@edk2.groups.io; Liu, Zhiguang <zhiguang....@intel.com>
> Cc: Liming Gao <gaolim...@byosoft.com.cn>; Wu, Jiaxin
> <jiaxin...@intel.com>; Ni, Ray <ray...@intel.com>
> Subject: Re: [edk2-devel] [PATCH v2 2/4] MdeModulePkg/SMM: Disallow
> unregister SMI handler in other SMI handler
>
> On 2/28/24 03:27, Zhiguang Liu wrote:
> > In last patch, we add code support to unregister SMI handler inside
> > itself. However, the code doesn't support unregister SMI handler
> > insider other SMI handler. While this is not a must-have usage.
> > So add check to disallow unregister SMI handler in other SMI handler.
> >
> > Cc: Liming Gao <gaolim...@byosoft.com.cn>
> > Cc: Jiaxin Wu <jiaxin...@intel.com>
> > Cc: Ray Ni <ray...@intel.com>
> > Cc: Laszlo Ersek <ler...@redhat.com>
> > Signed-off-by: Zhiguang Liu <zhiguang....@intel.com>
> > ---
> > MdeModulePkg/Core/PiSmmCore/Smi.c | 32
> > +++++++++++++++++++++++--------
> > 1 file changed, 24 insertions(+), 8 deletions(-)
> >
> > diff --git a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > index 3489c130fd..1bfbc635fc 100644
> > --- a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > +++ b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > @@ -8,7 +8,8 @@
> >
> > #include "PiSmmCore.h"
> >
> > -LIST_ENTRY mSmiEntryList = INITIALIZE_LIST_HEAD_VARIABLE
> > (mSmiEntryList);
> > +SMI_HANDLER *gCurrentSmiHandler = NULL;
> > +LIST_ENTRY mSmiEntryList = INITIALIZE_LIST_HEAD_VARIABLE
> (mSmiEntryList);
> >
> > SMI_ENTRY mRootSmiEntry = {
> > SMI_ENTRY_SIGNATURE,
> > @@ -142,13 +143,18 @@ SmiManage (
> > // Link points to may be freed if unregister SMI handler.
> > //
> > Link = Link->ForwardLink;
> > -
> > - Status = SmiHandler->Handler (
> > - (EFI_HANDLE)SmiHandler,
> > - Context,
> > - CommBuffer,
> > - CommBufferSize
> > - );
> > + //
> > + // Assign gCurrentSmiHandle before calling the SMI handler and
> > + // set to NULL when it returns.
> > + //
> > + gCurrentSmiHandler = SmiHandler;
> > + Status = SmiHandler->Handler (
> > + (EFI_HANDLE)SmiHandler,
> > + Context,
> > + CommBuffer,
> > + CommBufferSize
> > + );
> > + gCurrentSmiHandler = NULL;
> >
> > switch (Status) {
> > case EFI_INTERRUPT_PENDING:
> > @@ -328,6 +334,16 @@ SmiHandlerUnRegister (
> > return EFI_INVALID_PARAMETER;
> > }
> >
> > + //
> > + // Check if unregister SMI handler inside a SMI Handler // if
> > + (gCurrentSmiHandler != NULL) {
> > + //
> > + // Only allow to unregister SMI Handler inside itself.
> > + //
> > + ASSERT (gCurrentSmiHandler == SmiHandler); }
> > +
> > SmiEntry = SmiHandler->SmiEntry;
> >
> > RemoveEntryList (&SmiHandler->Link);
>
> (1) Why not:
>
> if ((gCurrentSmiHandler != NULL) && (gCurrentSmiHandler != SmiHandler)) {
> return EFI_INVALID_PARAMETER;
> }
>
> ?
>
> (2) Why do we call the new global variable "gCurrentSmiHandler" rather than
> "mCurrentSmiHandler"?
>
> Thanks
> Laszlo
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