From: Borislav Petkov <bp@alien8.de>
To: "Peter Zijlstra" <peterz@infradead.org>, "Jörg Rödel" <joro@8bytes.org>
Cc: x86@kernel.org, Joan Bruguera <joanbrugueram@gmail.com>,
linux-kernel@vger.kernel.org, Juergen Gross <jgross@suse.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
xen-devel <xen-devel@lists.xenproject.org>,
Jan Beulich <jbeulich@suse.com>,
Roger Pau Monne <roger.pau@citrix.com>,
Kees Cook <keescook@chromium.org>,
mark.rutland@arm.com, Andrew Cooper <Andrew.Cooper3@citrix.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2 2/7] x86/boot: Delay sev_verify_cbit() a bit
Date: Thu, 19 Jan 2023 14:18:47 +0100 [thread overview]
Message-ID: <Y8lDN73cNOmNuciV@zn.tnic> (raw)
In-Reply-To: <20230116143645.649204101@infradead.org>
On Mon, Jan 16, 2023 at 03:25:35PM +0100, Peter Zijlstra wrote:
> Per the comment it is important to call sev_verify_cbit() before the
> first RET instruction, this means we can delay calling this until more
Make that "... this means that this can be delayed until... "
And I believe this is not about the first RET insn but about the *next* RET
which will pop poisoned crap from the unencrypted stack and do shits with it.
Also, there's this over sev_verify_cbit():
* sev_verify_cbit() is called before switching to a new long-mode page-table
* at boot.
so you can't move it under the
movq %rax, %cr3
Looking at this more, there's a sme_enable() call on the BSP which is already in
C.
So, can we do that C-bit verification once on the BSP, *in C* which would be a
lot easier, and be done with it?
Once it is verified there, the bit is the same on all APs so all good.
Right?
joro?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-01-19 13:19 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-16 14:25 [PATCH v2 0/7] x86: retbleed=stuff fixes Peter Zijlstra
2023-01-16 14:25 ` [PATCH v2 1/7] x86/boot: Remove verify_cpu() from secondary_startup_64() Peter Zijlstra
2023-01-17 9:25 ` Ingo Molnar
2023-01-18 9:45 ` Peter Zijlstra
2023-01-18 11:46 ` kirill.shutemov
2023-01-19 19:35 ` H. Peter Anvin
2023-01-26 14:15 ` Peter Zijlstra
2023-01-16 14:25 ` [PATCH v2 2/7] x86/boot: Delay sev_verify_cbit() a bit Peter Zijlstra
2023-01-19 13:18 ` Borislav Petkov [this message]
2023-01-20 12:43 ` Jörg Rödel
2023-01-16 14:25 ` [PATCH v2 3/7] x86/power: De-paravirt restore_processor_state() Peter Zijlstra
2023-01-20 20:26 ` Borislav Petkov
2023-01-16 14:25 ` [PATCH v2 4/7] x86/power: Inline write_cr[04]() Peter Zijlstra
2023-01-20 20:29 ` Borislav Petkov
2023-01-16 14:25 ` [PATCH v2 5/7] x86/callthunk: No callthunk for restore_processor_state() Peter Zijlstra
2023-01-16 14:25 ` [PATCH v2 6/7] x86/power: Sprinkle some noinstr Peter Zijlstra
2023-01-17 9:31 ` Ingo Molnar
2023-01-17 11:29 ` Peter Zijlstra
2023-01-17 11:54 ` Ingo Molnar
2023-01-16 14:25 ` [PATCH v2 7/7] PM / hibernate: Add minimal noinstr annotations Peter Zijlstra
2023-01-18 1:54 ` [PATCH v2 0/7] x86: retbleed=stuff fixes Joan Bruguera
2023-05-16 13:59 ` Josh Poimboeuf
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=Y8lDN73cNOmNuciV@zn.tnic \
--to=bp@alien8.de \
--cc=Andrew.Cooper3@citrix.com \
--cc=hpa@zytor.com \
--cc=jbeulich@suse.com \
--cc=jgross@suse.com \
--cc=joanbrugueram@gmail.com \
--cc=joro@8bytes.org \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=peterz@infradead.org \
--cc=rafael@kernel.org \
--cc=roger.pau@citrix.com \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xenproject.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