linux-kernel - Re: [PATCH 20/31] mips/kvm: Hook into TLB fault handlers.

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Message-ID: <51B2779F.3030903@caviumnetworks.com>
Date:	Fri, 7 Jun 2013 17:15:27 -0700
From:	David Daney <ddaney@...iumnetworks.com>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
CC:	David Daney <ddaney.cavm@...il.com>, <linux-mips@...ux-mips.org>,
	<ralf@...ux-mips.org>, <kvm@...r.kernel.org>,
	Sanjay Lal <sanjayl@...asys.com>,
	<linux-kernel@...r.kernel.org>,
	David Daney <david.daney@...ium.com>
Subject: Re: [PATCH 20/31] mips/kvm: Hook into TLB fault handlers.

On 06/07/2013 04:34 PM, Sergei Shtylyov wrote:
> Hello.
>
> On 06/08/2013 03:03 AM, David Daney wrote:
>
>> From: David Daney <david.daney@...ium.com>
>>
>> If the CPU is operating in guest mode when a TLB related excpetion
>> occurs, give KVM a chance to do emulation.
>>
>> Signed-off-by: David Daney <david.daney@...ium.com>
>> ---
>>   arch/mips/mm/fault.c       | 8 ++++++++
>>   arch/mips/mm/tlbex-fault.S | 6 ++++++
>>   2 files changed, 14 insertions(+)
>>
>> diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
>> index 0fead53..9391da49 100644
>> --- a/arch/mips/mm/fault.c
>> +++ b/arch/mips/mm/fault.c
> [...]
>> @@ -50,6 +51,13 @@ asmlinkage void __kprobes do_page_fault(struct
>> pt_regs *regs, unsigned long writ
>>              field, regs->cp0_epc);
>>   #endif
>> +#ifdef CONFIG_KVM_MIPSVZ
>> +    if (test_tsk_thread_flag(current, TIF_GUESTMODE)) {
>> +        if (mipsvz_page_fault(regs, write, address))
>
>     Any reason not to collapse these into single *if*?
>

It makes the conditional call to mipsvz_page_fault() less obvious.

Certainly the same semantics can be achieved several different ways.

David Daney


>> +            return;
>> +    }
>> +#endif
>> +
>>
>
>


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