linux-kernel - Re: [PATCH 0/2 v4] kdump,vmcoreinfo: Export the value of sme mask to vmcoreinfo

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Date:   Wed, 26 Dec 2018 11:33:49 +0800
From:   Dave Young <dyoung@...hat.com>
To:     Lianbo Jiang <lijiang@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        akpm@...ux-foundation.org, bhe@...hat.com,
        linux-doc@...r.kernel.org, Kazuhito Hagio <khagio@...hat.com>,
        anderson@...hat.com
Subject: Re: [PATCH 0/2 v4] kdump,vmcoreinfo: Export the value of sme mask to
 vmcoreinfo

Add Kazu and Dave in cc

On 12/20/18 at 01:40pm, Lianbo Jiang wrote:
> This patchset did two things:
> a. add a new document for vmcoreinfo
> 
> This document lists some variables that export to vmcoreinfo, and briefly
> describles what these variables indicate. It should be instructive for
> many people who do not know the vmcoreinfo, and it also normalizes the
> exported variable as a convention between kernel and use-space.
> 
> b. export the value of sme mask to vmcoreinfo
> 
> 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.
> 
> Changes since v1:
> 1. No need to export a kernel-internal mask to userspace, so copy the
> value of sme_me_mask to a local variable 'sme_mask' and write the value
> of sme_mask to vmcoreinfo.
> 2. Add comment for the code.
> 3. Improve the patch log.
> 4. Add the vmcoreinfo documentation.
> 
> Changes since v2:
> 1. Improve the vmcoreinfo document, add more descripts for these
> variables exported.
> 2. Fix spelling errors in the document.
> 
> Changes since v3:
> 1. Still improve the vmcoreinfo document, and make it become more
> clear and easy to read.
> 2. Move sme_mask comments in the code to the vmcoreinfo document.
> 3. Improve patch log.
> 
> Lianbo Jiang (2):
>   kdump: add the vmcoreinfo documentation
>   kdump,vmcoreinfo: Export the value of sme mask to vmcoreinfo
> 
>  Documentation/kdump/vmcoreinfo.txt | 513 +++++++++++++++++++++++++++++
>  arch/x86/kernel/machine_kexec_64.c |   3 +
>  2 files changed, 516 insertions(+)
>  create mode 100644 Documentation/kdump/vmcoreinfo.txt
> 
> -- 
> 2.17.1
>