From eb24212304ec31c3ae8b878a21d4b875d5942cd1 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Tue, 28 Feb 2023 15:47:00 +0100 Subject: [PATCH 13/14] UefiCpuPkg/MpInitLib: fix apic mode for cpu hotplug In case the number of CPUs can in increase beyond 255 due to CPU hotplug choose x2apic mode. Signed-off-by: Gerd Hoffmann --- UefiCpuPkg/Library/MpInitLib/MpLib.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c index 6f1456cfe168..9277e06c9b4a 100644 --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c @@ -527,7 +527,9 @@ CollectProcessorCount ( // // Enable x2APIC mode if // 1. Number of CPU is greater than 255; or - // 2. There are any logical processors reporting an Initial APIC ID of 255 or greater. + // 2. The platform exposed the exact *boot* CPU count to us in advance, and + // more than 255 logical processors are possible later, with hotplug; or + // 3. There are any logical processors reporting an Initial APIC ID of 255 or greater. // X2Apic = FALSE; if (CpuMpData->CpuCount > 255) { @@ -535,6 +537,10 @@ CollectProcessorCount ( // If there are more than 255 processor found, force to enable X2APIC // X2Apic = TRUE; + } else if ((PcdGet32 (PcdCpuBootLogicalProcessorNumber) > 0) && + (PcdGet32 (PcdCpuMaxLogicalProcessorNumber) > 255)) + { + X2Apic = TRUE; } else { CpuInfoInHob = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob; for (Index = 0; Index < CpuMpData->CpuCount; Index++) { -- 2.41.0