linux-kernel - Re: [PATCH RFC V3 9/9] x86/pks: Add PKS test code

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Message-ID: <3f9ebe3b-5c1c-6a69-3779-6f90d66227bd@intel.com>
Date:   Tue, 13 Oct 2020 12:02:07 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     ira.weiny@...el.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Fenghua Yu <fenghua.yu@...el.com>, x86@...nel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH RFC V3 9/9] x86/pks: Add PKS test code

On 10/9/20 12:42 PM, ira.weiny@...el.com wrote:
>  #ifdef CONFIG_X86_32
>  	/*
>  	 * We can fault-in kernel-space virtual memory on-demand. The
> diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
> index cc3510cde64e..f9552bd9341f 100644
> --- a/include/linux/pkeys.h
> +++ b/include/linux/pkeys.h
> @@ -47,7 +47,6 @@ static inline bool arch_pkeys_enabled(void)
>  static inline void copy_init_pkru_to_fpregs(void)
>  {
>  }
> -
>  #endif /* ! CONFIG_ARCH_HAS_PKEYS */

^ Whitespace damage

>  #ifndef CONFIG_ARCH_HAS_SUPERVISOR_PKEYS
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 0c781f912f9f..f015c09ba5a1 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -2400,6 +2400,18 @@ config HYPERV_TESTING
>  	help
>  	  Select this option to enable Hyper-V vmbus testing.
>  
> +config PKS_TESTING
> +	bool "PKey(S)upervisor testing"

Seems like we need a space in there somewhere.

> +	pid = fork();
> +	if (pid == 0) {
> +		fd = open("/sys/kernel/debug/x86/run_pks", O_RDWR);
> +		if (fd < 0) {
> +			printf("cannot open file\n");
> +			return -1;
> +		}
> +

Will this return code make anybody mad?  Should we have a nicer return
code for when this is running on non-PKS hardware?

I'm not going to be too picky about this.  I'll just ask one question:
Has this found real bugs for you?

Reviewed-by: Dave Hansen <dave.hansen@...ux.intel.com>