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Date:   Tue, 3 Jul 2018 11:39:24 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     lijiang <lijiang@redhat.com>
Cc:     linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de,
        hpa@zytor.com, ebiederm@xmission.com, joro@8bytes.org,
        thomas.lendacky@amd.com, dyoung@redhat.com,
        kexec@lists.infradead.org, iommu@lists.linux-foundation.org,
        bhe@redhat.com
Subject: Re: [PATCH 1/5 V5] Add a function(ioremap_encrypted) for kdump when
 AMD sme enabled
Message-ID: <20180703093924.GA5748@zn.tnic>
References: <20180702072639.10110-1-lijiang@redhat.com>
 <20180702072639.10110-2-lijiang@redhat.com>
 <20180702101451.GB28730@zn.tnic>
 <4ae1cfb5-0a4b-2aac-2575-024e2c74826f@redhat.com>
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On Tue, Jul 03, 2018 at 10:17:19AM +0800, lijiang wrote:
> for example, the elfcorehdr. In fact, the elfcorehdr and notes

You mean this?

 ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
 {
-       return read_from_oldmem(buf, count, ppos, 0);
+       return read_from_oldmem(buf, count, ppos, 0, sme_active());

That looks encrypted to me.

> call the same function(read_from_oldmem->ioremap_cache), in this case,
> it is very difficult to properly remap the memory if the caller don't
> care whether the memory is encrypted.

So beef up the logic in __ioremap_caller() to figure out based on the
address whether to access the memory encrypted or not. You can find out
the elfcorehdr address in the capture kernel.

-- 
Regards/Gruss,
    Boris.

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