linux-kernel - Re: [PATCH V8 26/44] x86/fault: Print PKS MSR on fault

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Date:   Fri, 18 Feb 2022 12:54:11 -0800
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH V8 26/44] x86/fault: Print PKS MSR on fault

On Fri, Feb 18, 2022 at 12:20:58PM -0800, Dave Hansen wrote:
> On 2/18/22 09:28, Edgecombe, Rick P wrote:
> > On Thu, 2022-02-17 at 22:01 -0800, Ira Weiny wrote:
> >> Are you suggesting the PKRU should be printed instead or in addition
> >> to the
> >> PKS?
> > Well I was just thinking that PKRS should only be printed if it's an
> > access via a supervisor pte.
> 
> That's not *wrong* per se, but it's not what we do for PKU:
> 
>         if (cpu_feature_enabled(X86_FEATURE_OSPKE))
>                 printk("%sPKRU: %08x\n", log_lvl, read_pkru());
> 
> If the feature is enabled, we print the register.  We don't try to be
> fancy and decide if it's relevant to the oops.  Why don't you just stick
> PKRS on the same line as PKRU whenever it's supported?

Ah good point.  I'll do that.

Thanks,
Ira