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Kernel: Workaround QEMU hypervisor.framework CPUID max leaf bug

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This works around issue #10382 until it is fixed on QEMU's side.
Patch from Anonymous.
This commit is contained in:
Idan Horowitz 2022-02-11 02:45:34 +02:00
parent b683e8ab77
commit 1aad64fbe4
Notes: sideshowbarker 2024-07-17 19:02:09 +09:00 
Author: https://github.com/IdanHo
Commit: https://github.com/SerenityOS/serenity/commit/1aad64fbe4
2 changed files with 27 additions and 0 deletions
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3
Kernel/Arch/x86/Processor.h
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@ -84,6 +84,9 @@ class Processor {
static Atomic<u32> g_total_processors;
u8 m_physical_address_bit_width;
u8 m_virtual_address_bit_width;
#if ARCH(X86_64)
bool m_has_qemu_hvf_quirk;
#endif
ProcessorInfo* m_info;
Thread* m_current_thread;

24
Kernel/Arch/x86/common/Processor.cpp
View file

@ -143,6 +143,10 @@ UNMAP_AFTER_INIT void Processor::cpu_detect()
}
}
#if ARCH(X86_64)
m_has_qemu_hvf_quirk = false;
#endif
if (max_extended_leaf >= 0x80000008) {
// CPUID.80000008H:EAX[7:0] reports the physical-address width supported by the processor.
CPUID cpuid(0x80000008);
@ -154,6 +158,22 @@ UNMAP_AFTER_INIT void Processor::cpu_detect()
m_physical_address_bit_width = has_feature(CPUFeature::PAE) ? 36 : 32;
// Processors that do not support CPUID function 80000008H, support a linear-address width of 32.
m_virtual_address_bit_width = 32;
#if ARCH(X86_64)
// Workaround QEMU hypervisor.framework bug
// https://gitlab.com/qemu-project/qemu/-/issues/664
//
// We detect this as follows:
// * We're in a hypervisor
// * hypervisor_leaf_range is null under Hypervisor.framework
// * m_physical_address_bit_width is 36 bits
if (has_feature(CPUFeature::HYPERVISOR)) {
CPUID hypervisor_leaf_range(0x40000000);
if (!hypervisor_leaf_range.ebx() && m_physical_address_bit_width == 36) {
m_has_qemu_hvf_quirk = true;
m_virtual_address_bit_width = 48;
}
}
#endif
}
CPUID extended_features(0x7);
@ -389,6 +409,10 @@ UNMAP_AFTER_INIT void Processor::initialize(u32 cpu)
dmesgln("CPU[{}]: No RDRAND support detected, randomness will be poor", current_id());
dmesgln("CPU[{}]: Physical address bit width: {}", current_id(), m_physical_address_bit_width);
dmesgln("CPU[{}]: Virtual address bit width: {}", current_id(), m_virtual_address_bit_width);
#if ARCH(X86_64)
if (m_has_qemu_hvf_quirk)
dmesgln("CPU[{}]: Applied correction for QEMU Hypervisor.framework quirk", current_id());
#endif
if (cpu == 0)
idt_init();