When running qemu-i386 even with -cpu Nehalem (aka x86_64-v2), it raises the warning
TCG doesn't support requested feature: CPUID.80000001H:EDX.lm [bit 29] Likewise using qemu-x86_64 with -cpu Haswell, it raises warnings for TCG doesn't support requested feature: CPUID.01H:ECX.pcid [bit 17] TCG doesn't support requested feature: CPUID.01H:ECX.x2apic [bit 21] TCG doesn't support requested feature: CPUID.01H:ECX.tsc-deadline [bit 24] TCG doesn't support requested feature: CPUID.07H:EBX.invpcid [bit 10] Even though x86_64-v3 is the level that qemu-user is supposed to provide. These are two related problems: - for Haswell, the 4 missing features are only relevant to code running in kernel mode; we can ignore them and mark them as supported even though they are not. The supported features are only used to print the warnings - for qemu-i386, the issue is that this emulator is restricted to running programs on a 32-bit processor, even though it is actually emulating programs that use the 32-bit kernel ABI on any processor. The behavior the processor in compatibility (32-bit CS, EFER.LMA=1) mode is mostly the same as when EFER.LMA=0 and the little code that is needed to handle 64-bit ring-0 is even present in the qemu-i386 binary, just hidden behind checks for HF_LMA_MASK. So, LM can also be treated as a feature that is only relevant in kernel mode; not entirely, so this cannot yet be extended to bsd-user, but the required changes are minimal. Other CPU models have warnings for the ARCH_CAPABILITIES MSR; hide them as well in a similar manner. Based-on: <20230623131711.96775-1-pbonz...@redhat.com> Paolo Bonzini (3): target/i386: ignore ARCH_CAPABILITIES features in user mode emulation target/i386: ignore CPL0-specific features in user mode emulation target/i386: emulate 64-bit ring 0 for linux-user if LM feature is set linux-user/i386/cpu_loop.c | 57 ++++++++++---------- target/i386/cpu.c | 103 +++++++++++++++++++++++++++++++++--- target/i386/tcg/translate.c | 6 ++- 3 files changed, 126 insertions(+), 40 deletions(-) -- 2.41.0
