Re: [edk2-devel] [PATCH V1 1/1] MdeModulePkg/Variable: Fix volatile variable RT cache update logic

["Kubacki, Michael A" <michael.a.kubacki@intel.com>]

After a new volatile variable is written successfully, Runtime Services GetVariable () may return
EFI_NOT_FOUND for that variable.

Thanks,
Michael

> -----Original Message-----
> From: Gao, Liming <liming.gao@intel.com>
> Sent: Sunday, November 10, 2019 10:08 PM
> To: devel@edk2.groups.io; Kubacki, Michael A
> <michael.a.kubacki@intel.com>
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Wang, Jian J
> <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>; Gao, Liming
> <liming.gao@intel.com>
> Subject: RE: [edk2-devel] [PATCH V1 1/1] MdeModulePkg/Variable: Fix
> volatile variable RT cache update logic
> 
> Michael:
>   What real issue is caused by this issue?
> 
> Thanks
> Liming
> >-----Original Message-----
> >From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> >Kubacki, Michael A
> >Sent: Monday, November 11, 2019 1:16 PM
> >To: devel@edk2.groups.io
> >Cc: Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
> ><michael.d.kinney@intel.com>; Wang, Jian J <jian.j.wang@intel.com>; Wu,
> >Hao A <hao.a.wu@intel.com>
> >Subject: [edk2-devel] [PATCH V1 1/1] MdeModulePkg/Variable: Fix
> >volatile variable RT cache update logic
> >
> >REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2333
> >
> >During a SetVariable () invocation, UpdateVariable () is called.
> >UpdateVariable () contains logic to determine whether a volatile or
> >non-volatile UEFI variable was set so the corresponding runtime cache
> >can be updated to reflect the change. The current logic simply
> >evaluates Variable->Volatile to determine which runtime cache should be
> >updated.
> >
> >The problem is Variable->Volatile does not always reflect whether a
> >volatile variable is being set. Variable->Volatile is set to TRUE only
> >in the case a pre-existing variable is found in the volatile variable
> >store. Therefore, the value is FALSE when a new volatile variable is
> >written.
> >
> >This change updates the logic to take this into account. If a new
> >variable is written successfully, the Attributes will accurately
> >reflect whether the variable is non-volatile. If a pre-existing
> >variable is modified, the Volatile field will reflect the type of
> >variable (Attributes are not reliable; e.g. 0x0 indicates deletion).
> >
> >Cc: Liming Gao <liming.gao@intel.com>
> >Cc: Michael D Kinney <michael.d.kinney@intel.com>
> >Cc: Jian J Wang <jian.j.wang@intel.com>
> >Cc: Hao A Wu <hao.a.wu@intel.com>
> >Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
> >---
> > MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> >diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> >b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> >index 29d6aca993..75d33ff724 100644
> >--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> >+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> >@@ -2296,9 +2296,8 @@ UpdateVariable (
> >
> > Done:
> >   if (!EFI_ERROR (Status)) {
> >-    if (Variable->Volatile) {
> >-      VolatileCacheInstance = &(mVariableModuleGlobal-
> >>VariableGlobal.VariableRuntimeCacheContext.VariableRuntimeVolatileCac
> h
> >e);
> >-    } else {
> >+    VolatileCacheInstance = &(mVariableModuleGlobal-
> >>VariableGlobal.VariableRuntimeCacheContext.VariableRuntimeVolatileCac
> h
> >e);
> >+    if ((Variable->CurrPtr != NULL && !Variable->Volatile) ||
> >+ (Attributes &
> >EFI_VARIABLE_NON_VOLATILE) != 0) {
> >       VolatileCacheInstance = &(mVariableModuleGlobal-
> >>VariableGlobal.VariableRuntimeCacheContext.VariableRuntimeNvCache);
> >     }
> >
> >--
> >2.16.2.windows.1
> >
> >
> >
>