On 09/27/18 13:45, Laszlo Ersek wrote: > On 09/27/18 12:59, Marc-André Lureau wrote: >> Hi, >> >> According to "TCG Platform Reset Attack Mitigation Specification", if >> MOR bit is set, "it must initiate a vendor-specific method that >> overwrites all of system memory and the processor caches" >> >> In QuarkPlatformPkg/Platform/Pei/PlatformInit/MemoryCallback.c and >> QuarkPlatformPkg/Platform/Pei/PlatformInit/MrcWrapper.c, there is some >> code to clear RAM, however I don't see code that would clear the >> processor caches. >> >> For edk2/qemu, Paolo suggested it may be simpler to clear the cache >> unconditionally. How would you implement that? Using >> EFI_CPU_ARCH_PROTOCOL.FlushDataCache? (or direct AsmWbinvd call) > > I would call the appropriate low-level BaseLib.h function somewhere in > OvmfPkg/PlatformPei (unconditionally, yes). I haven't looked into > AsmWbinvd(), but if that's the right function, call that. (Checking the > Intel SDM re: WBINVD, I agree it could be the right one.)
BTW: I assume the caches should be flushed on all logical processors; is that correct? If so, then EFI_PEI_MP_SERVICES_PPI will be needed, to run AsmWbinvd() on all processors. Luckily, OvmfPkg/PlatformPei already uses that service; see "OvmfPkg/PlatformPei/FeatureControl.c". Thanks Laszlo _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
