From 7d3f71a6485791f9fb87621c5a15571889f6c687 Mon Sep 17 00:00:00 2001 From: Tim Schumacher Date: Thu, 5 May 2022 18:33:29 +0200 Subject: Kernel: Do not disable userland access to the RDTSC instruction Access to RDTSC is occasionally restricted to give malware one less option to accurately time attacks (side-channels, etc.). However, QEMU requires access to the timestamp counter for the exact same reason (which is accurately timing its CPU ticks), so lets just enable it for now. --- Kernel/Arch/x86/common/Processor.cpp | 4 ---- 1 file changed, 4 deletions(-) diff --git a/Kernel/Arch/x86/common/Processor.cpp b/Kernel/Arch/x86/common/Processor.cpp index a34e489ea8..ff388b22a8 100644 --- a/Kernel/Arch/x86/common/Processor.cpp +++ b/Kernel/Arch/x86/common/Processor.cpp @@ -551,10 +551,6 @@ UNMAP_AFTER_INIT void Processor::cpu_setup() write_cr4(read_cr4() | 0x800); } - if (has_feature(CPUFeature::TSC)) { - write_cr4(read_cr4() | 0x4); - } - if (has_feature(CPUFeature::XSAVE)) { // Turn on CR4.OSXSAVE write_cr4(read_cr4() | 0x40000); -- cgit v1.2.3