linux-kernel - Re: [PATCH v3 3/4] Revert "xen: Introduce 'xen_nopv' to disable PV extensions for HVM guests."

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Date:   Tue, 2 Jul 2019 12:38:01 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        boris.ostrovsky@...cle.co, jgross@...e.com, sstabellini@...nel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de
Subject: Re: [PATCH v3 3/4] Revert "xen: Introduce 'xen_nopv' to disable PV
 extensions for HVM guests."


On 2019/7/2 11:48, Boris Ostrovsky wrote:
> On Mon, Jul 01, 2019 at 10:20:27AM +0800, Zhenzhong Duan wrote:
>> This reverts commit 8d693b911bb9c57009c24cb1772d205b84c7985c.
>>
>> Instead we use an unified parameter 'nopv' for all the hypervisor
>> platforms.
>>
>> Signed-off-by: Zhenzhong Duan<zhenzhong.duan@...cle.com>
>> Reviewed-by: Juergen Gross<jgross@...e.com>
>> Cc: Boris Ostrovsky<boris.ostrovsky@...cle.com>
>> Cc: Juergen Gross<jgross@...e.com>
>> Cc: Stefano Stabellini<sstabellini@...nel.org>
>> Cc: Thomas Gleixner<tglx@...utronix.de>
>> Cc: Ingo Molnar<mingo@...hat.com>
>> Cc: Borislav Petkov<bp@...en8.de>
>> ---
>>   Documentation/admin-guide/kernel-parameters.txt |  4 ----
>>   arch/x86/xen/enlighten_hvm.c                    | 12 +-----------
>>   2 files changed, 1 insertion(+), 15 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index 21e08af..d5c3dcc 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -5251,10 +5251,6 @@
>>   			Disables the ticketlock slowpath using Xen PV
>>   			optimizations.
>>   
>> -	xen_nopv	[X86]
>> -			Disables the PV optimizations forcing the HVM guest to
>> -			run as generic HVM guest with no PV drivers.
>> -
> So someone upgrades the kernel and suddenly things work differently?
>
> At least there should be a warning that the option has been replaced
> with 'nopv' (but I would actually keep this option working as well).

OK, I'll add new patch to map xen_nopv to nopv. So if 'xen_nopv' is 
used, we go

to the path for 'nopv'. I will be same effect.

Thanks

Zhenzhong