From: Andrew Cooper <andrew.cooper3@citrix.com>
To: amit.shah@amd.com
Cc: Babu.Moger@amd.com, David.Kaplan@amd.com, Sandipan.Das@amd.com,
Thomas.Lendacky@amd.com, boris.ostrovsky@oracle.com,
bp@alien8.de, corbet@lwn.net, daniel.sneddon@linux.intel.com,
dave.hansen@linux.intel.com, hpa@zytor.com, jpoimboe@kernel.org,
kai.huang@intel.com, kvm@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, pawan.kumar.gupta@linux.intel.com,
pbonzini@redhat.com, peterz@infradead.org, seanjc@google.com,
tglx@linutronix.de, x86@kernel.org
Subject: Re: [PATCH 1/2] x86: cpu/bugs: add support for AMD ERAPS feature
Date: Mon, 4 Nov 2024 14:52:48 +0000 [thread overview]
Message-ID: <e9711ae1-b983-4f3e-89b4-513db62e4eef@citrix.com> (raw)
In-Reply-To: <c3fbf18a4ec015039388617ed899db98272cf181.camel@amd.com>
> Unfortunately, that's all we have right now in the official
> documentation.
>
> I've put up some notes in
> https://amitshah.net/2024/11/eraps-reduces-software-tax-for-hardware-bugs/
I appreciate the attempt to get a few details out, but this is very
confused on bunch of details.
Most importantly, you've described Intel RSB underflows, but named it
AMD BTC.
"Retbleed" is two totally different things. I begged the discoverers
to give it two names, and I also begged the x86 maintainers to not alias
them in Linux's view of the world, but alas.
AMD's BTC comes from a bad branch type prediction, and a late resteer
from the ret uop executing. It has nothing to do with RAS/RSB
underflow conditions.
~Andrew
next prev parent reply other threads:[~2024-11-04 14:52 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-31 15:39 [PATCH 0/2] Add support for the ERAPS feature Amit Shah
2024-10-31 15:39 ` [PATCH 1/2] x86: cpu/bugs: add support for AMD " Amit Shah
2024-10-31 23:03 ` Pawan Gupta
2024-11-04 8:57 ` Shah, Amit
2024-11-04 14:52 ` Andrew Cooper [this message]
2024-11-04 15:00 ` Shah, Amit
2024-10-31 23:11 ` Dave Hansen
2024-11-04 8:58 ` Shah, Amit
2024-11-04 16:11 ` Dave Hansen
2024-11-04 16:13 ` Shah, Amit
2024-11-04 16:26 ` Dave Hansen
2024-11-04 17:22 ` Shah, Amit
2024-11-04 17:45 ` Dave Hansen
2024-11-05 0:04 ` Andrew Cooper
2024-11-05 10:39 ` Shah, Amit
2024-11-05 14:54 ` Kaplan, David
2024-11-05 16:19 ` Dave Hansen
2024-11-05 16:25 ` Shah, Amit
2024-10-31 15:39 ` [PATCH 2/2] x86: kvm: svm: add support for ERAPS and FLUSH_RAP_ON_VMRUN Amit Shah
2024-10-31 23:13 ` Pawan Gupta
2024-11-01 4:14 ` kernel test robot
2024-11-01 9:26 ` Amit Shah
2024-11-04 5:18 ` Borislav Petkov
2024-11-04 11:16 ` Shah, Amit
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