From: Dave Hansen <dave.hansen@intel.com>
To: Amit Shah <amit@kernel.org>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
x86@kernel.org, linux-doc@vger.kernel.org
Cc: amit.shah@amd.com, thomas.lendacky@amd.com, bp@alien8.de,
tglx@linutronix.de, peterz@infradead.org, jpoimboe@kernel.org,
pawan.kumar.gupta@linux.intel.com, corbet@lwn.net,
mingo@redhat.com, dave.hansen@linux.intel.com, hpa@zytor.com,
seanjc@google.com, pbonzini@redhat.com,
daniel.sneddon@linux.intel.com, kai.huang@intel.com,
sandipan.das@amd.com, boris.ostrovsky@oracle.com,
Babu.Moger@amd.com, david.kaplan@amd.com
Subject: Re: [PATCH 1/2] x86: cpu/bugs: add support for AMD ERAPS feature
Date: Thu, 31 Oct 2024 16:11:51 -0700 [thread overview]
Message-ID: <05c12dec-3f39-4811-8e15-82cfd229b66a@intel.com> (raw)
In-Reply-To: <20241031153925.36216-2-amit@kernel.org>
On 10/31/24 08:39, Amit Shah wrote:
...
> With the Enhanced Return Address Prediction Security feature, any
> hardware TLB flush results in flushing of the RSB (aka RAP in AMD spec).
> This guarantees an RSB flush across context switches.
Check out the APM, volume 2: "5.5.1 Process Context Identifier"
... when system software switches address spaces (by writing ...
CR3[62:12]), the processor may use TLB mappings previously
stored for that address space and PCID, providing that bit 63 of
the source operand is set to 1.
tl;dr: PCIDs mean you don't necessarily flush the TLB on context switches.
next prev parent reply other threads:[~2024-10-31 23:11 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
2024-11-04 15:00 ` Shah, Amit
2024-10-31 23:11 ` Dave Hansen [this message]
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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