linux-kernel - Re: [PATCHv2] perf kvm: add kvm-stat for arm64

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Message-ID: <20200915132109.GB32758@leoy-ThinkPad-X240s>
Date:   Tue, 15 Sep 2020 21:21:09 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will@...nel.org>,
        John Garry <john.garry@...wei.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Suleiman Souhlal <suleiman@...gle.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCHv2] perf kvm: add kvm-stat for arm64

On Tue, Sep 15, 2020 at 08:15:41PM +0900, Sergey Senozhatsky wrote:
> On (20/09/15 19:57), Sergey Senozhatsky wrote:
> > On (20/09/15 18:36), Leo Yan wrote:
> > > > +#define HVC_STUB_ERR		  0xbadca11
> > > > +
> > > > +/* Per asm/kvm_asm.h */
> > > > +#define ARM_EXCEPTION_IRQ		0
> > > > +#define ARM_EXCEPTION_EL1_SERROR	1
> > > > +#define ARM_EXCEPTION_TRAP		2
> > > > +#define ARM_EXCEPTION_IL		3
> > >
> > > Nitpick: from completeness, we also can give out KVM exiting reason
> > > for 'ARM_EXCEPTION_IL'.
> >
> > OK, let me take a look.
> 
> I think ARM_EXCEPTION_IL are reported as HYP_GONE. According to
> arch/arm64/include/asm/kvm_asm.h
> 
> ---
> #define ARM_EXCEPTION_IRQ	  0
> #define ARM_EXCEPTION_EL1_SERROR  1
> #define ARM_EXCEPTION_TRAP	  2
> #define ARM_EXCEPTION_IL	  3
> 
> #define kvm_arm_exception_type					\
> 	{ARM_EXCEPTION_IRQ,		"IRQ"		},	\
> 	{ARM_EXCEPTION_EL1_SERROR, 	"SERROR"	},	\
> 	{ARM_EXCEPTION_TRAP, 		"TRAP"		},	\
> 	{ARM_EXCEPTION_HYP_GONE,	"HYP_GONE"	}
> ---
> 
> So it should be reported already.

Thanks for double checking.  But I still think this is incorrect,
ARM_EXCEPTION_HYP_GONE is defined as HVC_STUB_ERR (0xbadca11), which
is different from ARM_EXCEPTION_IL (3).  So I don't understand why you
have the conclusion that 'ARM_EXCEPTION_IL are reported as HYP_GONE'.

Sorry if I miss anything for this.

Thanks,
Leo