From 199de89677deffffff30eda7ad17793b30042cce Mon Sep 17 00:00:00 2001 From: Jian J Wang Date: Fri, 26 Jan 2018 16:30:40 +0800 Subject: [PATCH] UefiCpuPkg/MpInitLib: force flushing TLB for AP in mwait loop mode The reason doing this is that we found that calling StartupAllAps() to flush TLB for all APs in CpuDxe driver after changing page attributes will spend a lot of time to complete. If there are many page attributes update requests, the whole system performance will be slowed down explicitly, including any shell command and UI operation. The solution is removing the flush operation for AP in CpuDxe driver. Since TLB is always flushed in HLT loop mode, we just need to enforce a TLB flush for mwait loop mode. Cc: Ruiyu Ni Cc: Jiewen Yao Cc: Eric Dong Cc: Laszlo Ersek Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang Reviewed-by: Ruiyu Ni --- UefiCpuPkg/Library/MpInitLib/MpLib.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c index f8ab5f115d..f2ff40417a 100644 --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c @@ -639,6 +639,13 @@ ApWakeupFunction ( // Restore AP's volatile registers saved // RestoreVolatileRegisters (&CpuMpData->CpuData[ProcessorNumber].VolatileRegisters, TRUE); + } else { + // + // The CPU driver might not flush TLB for APs on spot after updating + // page attributes. AP in mwait loop mode needs to take care of it when + // woken up. + // + CpuFlushTlb (); } if (GetApState (&CpuMpData->CpuData[ProcessorNumber]) == CpuStateReady) {