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Date: Thu, 23 May 2024 16:52:02 +0200
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Cc: alexandre.chartre@oracle.com, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH] x86/bhi: BHI mitigation can trigger warning in #DB
 handler
Content-Language: en-US
To: Dave Hansen <dave.hansen@intel.com>, x86@kernel.org, kvm@vger.kernel.org
References: <20240523123322.3326690-1-alexandre.chartre@oracle.com>
 <a04d82be-a0d6-4e53-b47c-dba8402199e7@intel.com>
From: Alexandre Chartre <alexandre.chartre@oracle.com>
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On 5/23/24 16:28, Dave Hansen wrote:
> On 5/23/24 05:33, Alexandre Chartre wrote:
>> The problem can be reproduced with the following sequence:
>>
>>   $ cat sysenter_step.c
>>   int main()
>>   { asm("pushf; pop %ax; bts $8,%ax; push %ax; popf; sysenter"); }
>>
>>   $ gcc -o sysenter_step sysenter_step.c
>>
>>   $ ./sysenter_step
>>   Segmentation fault (core dumped)
>>
>> The program is expected to crash, and the #DB handler will issue a warning.
> 
> Should we wrap up this gem and put it with the other entry selftests?

It looks like tools/testing/selftests/x86/single_step_syscall.c tests
sysenter with TF set but it doesn't check if the kernel issues any
warning.

alex.