From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Dimitri John Ledkov <dimitri.ledkov@canonical.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available
Date: Thu, 28 Jul 2022 09:39:20 -0300 [thread overview]
Message-ID: <YuKDeFg8TtV9zcw9@quatroqueijos> (raw)
In-Reply-To: <YuKCpLOLeDOI7GII@zn.tnic>
On Thu, Jul 28, 2022 at 02:35:48PM +0200, Borislav Petkov wrote:
> drop stable@
>
> On Thu, Jul 28, 2022 at 09:26:02AM -0300, Thadeu Lima de Souza Cascardo wrote:
> > Some cloud hypervisors do not provide IBPB on very recent CPU processors,
> > including AMD processors affected by Retbleed.
>
> Which hypervisors are those? How relevant is that use case?
Azure for sure, and I guess AWS would be affected as well.
>
> How do I reproduce it here?
>
qemu -cpu host,ibpb=off on an affected AMD processor worked for me. With EFI,
so with something like -drive if=pflash,index=0,file=OVMF_CODE_4M.fd -drive
if=pflash,index=1,file=OVMF_VARS_4M.fd.
Cascardo.
> Thx.
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-07-28 12:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-28 12:26 [PATCH] x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available Thadeu Lima de Souza Cascardo
2022-07-28 12:35 ` Borislav Petkov
2022-07-28 12:39 ` Thadeu Lima de Souza Cascardo [this message]
2022-07-28 14:33 ` Dimitri John Ledkov
2022-07-28 15:18 ` Borislav Petkov
2022-07-28 15:50 ` Borislav Petkov
2022-07-28 17:01 ` Thadeu Lima de Souza Cascardo
2022-07-29 18:22 ` Borislav Petkov
2022-07-28 15:16 ` Peter Zijlstra
2022-07-29 8:11 ` [tip: x86/urgent] " tip-bot2 for Thadeu Lima de Souza Cascardo
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=YuKDeFg8TtV9zcw9@quatroqueijos \
--to=cascardo@canonical.com \
--cc=bp@alien8.de \
--cc=dimitri.ledkov@canonical.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--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).