From: Borislav Petkov <bp@alien8.de>
To: lijiang <lijiang@redhat.com>
Cc: thomas.lendacky@amd.com, jroedel@suse.de, brijesh.singh@amd.com,
bhe@redhat.com, tiwai@suse.de, x86@kernel.org,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, baiyaowei@cmss.chinamobile.com, hpa@zytor.com,
bhelgaas@google.com, tglx@linutronix.de, dyoung@redhat.com,
akpm@linux-foundation.org, dan.j.williams@intel.com
Subject: Re: [PATCH v7 RESEND 2/4] kexec: allocate unencrypted control pages for kdump in case SME is enabled
Date: Fri, 28 Sep 2018 09:57:11 +0200 [thread overview]
Message-ID: <20180928075654.GA20768@zn.tnic> (raw)
In-Reply-To: <ef91c6cd-03dd-1a72-eea8-97d05d0ad370@redhat.com>
On Fri, Sep 28, 2018 at 11:52:21AM +0800, lijiang wrote:
> There are two functions that are usually called in pairs, they are:
> arch_kexec_post_alloc_pages() and arch_kexec_pre_free_pages().
>
> One marks the pages as decrypted, another one marks the pages as encrypted.
>
> But for the crash control pages, no need to call arch_kexec_pre_free_pages(),
> there are three reasons:
> 1. Crash pages are reserved in memblock, these pages are only used by kdump,
> no other people uses these pages;
>
> 2. Whenever crash pages are allocated, these pages are always marked as
> decrypted(when SME is active);
>
> 3. If we plan to call the arch_kexe_pre_free_pages(), we have to store these
> pages to somewhere, which will have more code changes.
I don't think any of that answers the question *why* control pages do
not need to be marked encrypted again. And I think the reason is simple:
because you don't really need to, because once the crash kernel is done,
you reboot the box.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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next prev parent reply other threads:[~2018-09-28 7:58 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 7:19 [PATCH v7 RESEND 0/4] Support kdump for AMD secure memory encryption(SME) Lianbo Jiang
2018-09-27 7:19 ` [PATCH v7 RESEND 1/4] x86/ioremap: add a function ioremap_encrypted() to remap kdump old memory Lianbo Jiang
2018-09-27 13:17 ` Borislav Petkov
2018-09-27 14:53 ` lijiang
2018-09-27 16:10 ` Borislav Petkov
2018-09-28 0:33 ` lijiang
2018-09-27 7:19 ` [PATCH v7 RESEND 2/4] kexec: allocate unencrypted control pages for kdump in case SME is enabled Lianbo Jiang
2018-09-27 16:53 ` Borislav Petkov
2018-09-28 3:52 ` lijiang
2018-09-28 7:57 ` Borislav Petkov [this message]
2018-09-28 10:09 ` lijiang
2018-09-29 8:53 ` Borislav Petkov
2018-09-27 7:19 ` [PATCH v7 RESEND 3/4] iommu/amd: Remap the device table of IOMMU with the memory encryption mask for kdump Lianbo Jiang
2018-09-27 7:19 ` [PATCH v7 RESEND 4/4] kdump/vmcore: support encrypted old memory with SME enabled Lianbo Jiang
2018-09-28 8:38 ` Borislav Petkov
2018-09-29 6:24 ` lijiang
2018-09-29 8:30 ` Borislav Petkov
2018-09-29 9:36 ` lijiang
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