Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 17 Dec 2018 14:01:29 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Lianbo Jiang <lijiang@redhat.com>
Cc:     linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
        tglx@linutronix.de, mingo@redhat.com, x86@kernel.org,
        akpm@linux-foundation.org, bhe@redhat.com, dyoung@redhat.com,
        linux-doc@vger.kernel.org
Subject: Re: [PATCH 2/2 v3] kdump,vmcoreinfo: Export the value of sme mask to
 vmcoreinfo
Message-ID: <20181217130129.GE12165@zn.tnic>
References: <20181216131617.2612-1-lijiang@redhat.com>
 <20181216131617.2612-3-lijiang@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20181216131617.2612-3-lijiang@redhat.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, Dec 16, 2018 at 09:16:17PM +0800, Lianbo Jiang wrote:
> For AMD machine with SME feature, makedumpfile tools need to know
> whether the crash kernel was encrypted or not. If SME is enabled
> in the first kernel, the crash kernel's page table(pgd/pud/pmd/pte)
> contains the memory encryption mask, so need to remove the sme mask
> to obtain the true physical address.
> 
> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
> ---
>  arch/x86/kernel/machine_kexec_64.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index 4c8acdfdc5a7..1860fe24117d 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -352,10 +352,24 @@ void machine_kexec(struct kimage *image)
>  
>  void arch_crash_save_vmcoreinfo(void)
>  {
> +	u64 sme_mask = sme_me_mask;
> +
>  	VMCOREINFO_NUMBER(phys_base);
>  	VMCOREINFO_SYMBOL(init_top_pgt);
>  	vmcoreinfo_append_str("NUMBER(pgtable_l5_enabled)=%d\n",
>  			pgtable_l5_enabled());
> +	/*
> +	 * Currently, the local variable 'sme_mask' stores the value of
> +	 * sme_me_mask(bit 47), and also write the value of sme_mask to
> +	 * the vmcoreinfo.
> +	 * If need, the bit(sme_mask) might be redefined in the future,
> +	 * but the 'bit63' will be reserved.
> +	 * For example:
> +	 * [ misc	   ][ enc bit  ][ other misc SME info       ]
> +	 * 0000_0000_0000_0000_1000_0000_0000_0000_0000_0000_..._0000
> +	 * 63   59   55   51   47   43   39   35   31   27   ... 3
> +	 */

This text belongs into the document.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.