Re: [PATCH] x86/xen: Fix __xen_hypercall_setfunc

["Jürgen Groß" <jgross@suse.com>]

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On 11.04.25 11:27, Ingo Molnar wrote:
> 
> * Juergen Gross <jgross@suse.com> wrote:
> 
>> On 10.04.25 21:31, Jason Andryuk wrote:
>>> Hypercall detection is failing with xen_hypercall_intel() chosen even on
>>> an AMD processor.  Looking at the disassembly, the call to
>>> xen_get_vendor() was removed.
>>>
>>> The check for boot_cpu_has(X86_FEATURE_CPUID) was used as a proxy for
>>> the x86_vendor having been set.  When
>>> CONFIG_X86_REQUIRED_FEATURE_CPUID=y (the default value), DCE eliminates
>>> the call to xen_get_vendor().  An uninitialized value 0 means
>>> X86_VENDOR_INTEL, so the Intel function is always returned.
>>>
>>> Remove the if and always call xen_get_vendor() to avoid this issue.
>>>
>>> Fixes: 3d37d9396eb3 ("x86/cpufeatures: Add {REQUIRED,DISABLED} feature configs")
>>> Suggested-by: Juergen Gross <jgross@suse.com>
>>> Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>
>>
>> Reviewed-by: Juergen Gross <jgross@suse.com>
> 
> Wanna merge this via the Xen tree, or should it go to x86/urgent?
> 
> The bug was *caused* by the x86 tree so we'd be glad to merge,
> but your call.

x86/urgent is fine for me.


Juergen

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