linux-kernel - Re: [PATCH v5 4/5] x86/paravirt: switch mixed paravirt/alternative calls to alternative

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Date:   Fri, 8 Dec 2023 12:53:47 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        virtualization@...ts.linux.dev,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ajay Kaher <akaher@...are.com>,
        Alexey Makhalov <amakhalov@...are.com>,
        VMware PV-Drivers Reviewers <pv-drivers@...are.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v5 4/5] x86/paravirt: switch mixed paravirt/alternative
 calls to alternative_2

On 06.12.23 12:08, Borislav Petkov wrote:
> On Wed, Nov 29, 2023 at 02:33:31PM +0100, Juergen Gross wrote:
>> Instead of stacking alternative and paravirt patching, use the new
>> ALT_FLAG_CALL flag to switch those mixed calls to pure alternative
>> handling.
>>
>> This eliminates the need to be careful regarding the sequence of
>> alternative and paravirt patching.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>> ---
>> V5:
>> - remove no longer needed extern declarations from alternative.c
>>    (Boris Petkov)
>> - add comment about ALTERNATIVE[_2]() macro usage (Boris Petkov)
>> - rebase to tip/master (Boris Petkov)
>> ---
>>   arch/x86/include/asm/alternative.h    |  5 ++--
>>   arch/x86/include/asm/paravirt.h       |  9 ++++--
>>   arch/x86/include/asm/paravirt_types.h | 40 +++++++++++++++------------
>>   arch/x86/kernel/alternative.c         |  1 -
>>   arch/x86/kernel/callthunks.c          | 17 ++++++------
>>   arch/x86/kernel/module.c              | 20 ++++----------
>>   6 files changed, 44 insertions(+), 48 deletions(-)
> 
> After this one: (.config is attached).
...

Ouch.

Took me a while to find it. Patch 5 was repairing the issue again, and I tested
more thoroughly only with all 5 patches applied.


Juergen


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