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, akpm@linux-foundation.org,
x86@kernel.org, hpa@zytor.com, dyoung@redhat.com, bhe@redhat.com,
Thomas.Lendacky@amd.com, brijesh.singh@amd.com
Subject: Re: [PATCH 1/3 v2] x86/kexec: Do not map the kexec area as decrypted when SEV is active
Date: Tue, 2 Apr 2019 12:32:01 +0200 [thread overview]
Message-ID: <20190402103201.GF6826@zn.tnic> (raw)
In-Reply-To: <20190327053629.17935-2-lijiang@redhat.com>
On Wed, Mar 27, 2019 at 01:36:27PM +0800, Lianbo Jiang wrote:
> Currently, the arch_kexec_post_{alloc,free}_pages() unconditionally
> maps the kexec area as decrypted. This works fine when SME is active.
> Because in SME, the first kernel is loaded in decrypted area by the
> BIOS, so the second kernel must be also loaded into the decrypted
> memory.
>
> When SEV is active, the first kernel is loaded into the encrypted
> area, so the second kernel must be also loaded into the encrypted
> memory. Lets make sure that arch_kexec_post_{alloc,free}_pages()
> does not clear the memory encryption mask from the kexec area when
> SEV is active.
This commit message still doesn't explain the big picture why you want
this change.
And it must explain it because it might be all clear in your head now
but months from now, you, we, all would've forgotten why this change was
needed.
So pls add blurb that this whole effort is being done so that SEV VMs
can kdump too. I.e., the 10000ft picture.
Anyone must be able to figure out *why* a change has been done just by
doing git archeology. So make sure you explain it properly.
If unsure, try to put yourself in the shoes of some future kernel
developer who is trying to find out why this change has been done. Now
read the commit message you've written. Does it make any sense to him? I
think not.
Do you catch my drift?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2019-04-02 10:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-27 5:36 [PATCH 0/3 v2] Add kdump support for the SEV enabled guest Lianbo Jiang
2019-03-27 5:36 ` [PATCH 1/3 v2] x86/kexec: Do not map the kexec area as decrypted when SEV is active Lianbo Jiang
2019-04-02 10:32 ` Borislav Petkov [this message]
2019-04-26 1:59 ` lijiang
2019-04-26 13:02 ` Borislav Petkov
2019-04-28 1:29 ` lijiang
2019-03-27 5:36 ` [PATCH 2/3 v2] x86/kexec: Set the C-bit in the identity map page table " Lianbo Jiang
2019-03-27 5:36 ` [PATCH 3/3 v2] kdump,proc/vmcore: Enable kdumping encrypted memory when SEV was active Lianbo Jiang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190402103201.GF6826@zn.tnic \
--to=bp@alien8.de \
--cc=Thomas.Lendacky@amd.com \
--cc=akpm@linux-foundation.org \
--cc=bhe@redhat.com \
--cc=brijesh.singh@amd.com \
--cc=dyoung@redhat.com \
--cc=hpa@zytor.com \
--cc=kexec@lists.infradead.org \
--cc=lijiang@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).