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
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