Re: [PATCH v3 01/10] target/i386: Sync AMD CPUID aliases for Hygon

On Mon, Aug 24, 2026 at 12:53:05PM +0800, Tina Zhang wrote:
> Date: Mon, 24 Aug 2026 12:53:05 +0800
> From: Tina Zhang <[email protected]>
> Subject: [PATCH v3 01/10] target/i386: Sync AMD CPUID aliases for Hygon
> X-Mailer: git-send-email 2.43.7
> 
> AMD defines CPUID[0x80000001].EDX bits as aliases for a subset of
> CPUID[1].EDX.  QEMU currently synchronizes those aliases only when the
> guest CPU vendor is AuthenticAMD.
> 
> Hygon Dhyana uses the HygonGenuine vendor string, but implements the
> same AMD-compatible extended CPUID feature aliases.  This can leave QEMU
> advertising a feature in CPUID[1].EDX while the matching extended alias
> in CPUID[0x80000001].EDX stays clear.  This inconsistent CPUID state can
> confuse guest OS feature detection.
> 
> Apply the alias synchronization to Hygon CPUs as well.  Gate the new
> behavior with x-hygon-vendor-abi-fixes and disable it for pc-11.1 and
> older machine types, because the CPUID result is guest-visible ABI and
> must remain migration-compatible.
> 
> Add qtest coverage for the Dhyana model, including the compat property.
> 
> Signed-off-by: Tina Zhang <[email protected]>
> Tested-by: Yongwei Xu <[email protected]>
> ---
>  hw/i386/pc.c                        |  4 +-
>  target/i386/cpu.c                   | 10 ++--
>  target/i386/cpu.h                   | 12 +++++
>  tests/qtest/test-x86-cpuid-compat.c | 76 +++++++++++++++++++++++++++++
>  4 files changed, 98 insertions(+), 4 deletions(-)

Reviewed-by: Zhao Liu <[email protected]>