From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org, amit@kernel.org,
kvm@vger.kernel.org, amit.shah@amd.com, thomas.lendacky@amd.com,
bp@alien8.de, tglx@linutronix.de, peterz@infradead.org,
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, dwmw@amazon.co.uk,
andrew.cooper3@citrix.com
Subject: Re: [PATCH 2/2] x86/bugs: Don't fill RSB on context switch with eIBRS
Date: Wed, 20 Nov 2024 10:42:38 -0800 [thread overview]
Message-ID: <20241120184238.rddzpb7fhbhtqphr@desk> (raw)
In-Reply-To: <9792424a4fe23ccc1f7ebbef121bfdd31e696d5d.1732087270.git.jpoimboe@kernel.org>
On Tue, Nov 19, 2024 at 11:27:51PM -0800, Josh Poimboeuf wrote:
> User->user Spectre v2 attacks (including RSB) across context switches
> are already mitigated by IBPB in cond_mitigation(), if enabled globally
> or if at least one of the tasks has opted in to protection. RSB filling
Is below less ambiguous?
s/if at least one of the tasks/if previous or the next task/
> without IBPB serves no purpose for protecting user space, as indirect
> branches are still vulnerable.
>
> User->kernel RSB attacks are mitigated by eIBRS. In which case the RSB
> filling on context switch isn't needed. Fix that.
>
> While at it, update and coalesce the comments describing the various RSB
> mitigations.
>
> Suggested-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
next prev parent reply other threads:[~2024-11-20 18:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-20 7:27 [PATCH 0/2] x86/bugs: RSB tweaks Josh Poimboeuf
2024-11-20 7:27 ` [PATCH 1/2] x86/bugs: Don't fill RSB on VMEXIT with eIBRS+retpoline Josh Poimboeuf
2024-11-20 18:12 ` Pawan Gupta
2024-11-20 7:27 ` [PATCH 2/2] x86/bugs: Don't fill RSB on context switch with eIBRS Josh Poimboeuf
2024-11-20 10:27 ` Shah, Amit
2024-11-20 16:21 ` jpoimboe
2024-11-21 13:28 ` Shah, Amit
2024-11-20 15:24 ` Shah, Amit
2024-11-20 18:42 ` Pawan Gupta [this message]
2024-11-21 13:29 ` [PATCH 0/2] x86/bugs: RSB tweaks Shah, Amit
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