From: Nikolay Borisov <nik.borisov@suse.com>
To: Josh Poimboeuf <jpoimboe@kernel.org>, x86@kernel.org
Cc: 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,
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, dwmw@amazon.co.uk,
andrew.cooper3@citrix.com
Subject: Re: [PATCH v3 5/6] x86/bugs: Don't fill RSB on context switch with eIBRS
Date: Tue, 8 Apr 2025 16:51:43 +0300 [thread overview]
Message-ID: <80e2557d-b4b0-4097-9662-8772d2af25fe@suse.com> (raw)
In-Reply-To: <8979e2e1d9f48aa4480c2ebd5ea0f9e31f9707e5.1743617897.git.jpoimboe@kernel.org>
On 2.04.25 г. 21:19 ч., 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 either the prev or the next task has opted in to protection. RSB
> filling 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, so remove it.
>
> Suggested-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Reviewed-by: Amit Shah <amit.shah@amd.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
next prev parent reply other threads:[~2025-04-08 13:51 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-02 18:19 [PATCH v3 0/6] x86/bugs: RSB mitigation fixes and documentation Josh Poimboeuf
2025-04-02 18:19 ` [PATCH v3 1/6] x86/bugs: Rename entry_ibpb() Josh Poimboeuf
2025-04-02 18:29 ` Borislav Petkov
2025-04-02 18:44 ` Josh Poimboeuf
2025-04-02 18:48 ` Borislav Petkov
2025-04-02 19:37 ` Ingo Molnar
2025-04-03 0:34 ` Josh Poimboeuf
2025-04-02 18:19 ` [PATCH v3 2/6] x86/bugs: Use SBPB in __write_ibpb() if applicable Josh Poimboeuf
2025-04-02 20:41 ` Tom Lendacky
2025-04-03 2:12 ` Josh Poimboeuf
2025-04-02 21:04 ` Jim Mattson
2025-04-03 2:17 ` Josh Poimboeuf
2025-04-09 18:07 ` Jim Mattson
2025-04-09 18:29 ` Kaplan, David
2025-04-09 18:46 ` Jim Mattson
2025-04-02 18:19 ` [PATCH v3 3/6] x86/bugs: Fix RSB clearing in indirect_branch_prediction_barrier() Josh Poimboeuf
2025-04-04 14:45 ` Nikolay Borisov
2025-04-04 15:17 ` Josh Poimboeuf
2025-04-04 22:56 ` Nikolay Borisov
2025-04-05 0:56 ` Josh Poimboeuf
2025-04-08 7:15 ` Nikolay Borisov
2025-04-02 18:19 ` [PATCH v3 4/6] x86/bugs: Don't fill RSB on VMEXIT with eIBRS+retpoline Josh Poimboeuf
2025-04-08 13:50 ` Nikolay Borisov
2025-04-02 18:19 ` [PATCH v3 5/6] x86/bugs: Don't fill RSB on context switch with eIBRS Josh Poimboeuf
2025-04-08 13:51 ` Nikolay Borisov [this message]
2025-04-02 18:19 ` [PATCH v3 6/6] x86/bugs: Add RSB mitigation document Josh Poimboeuf
2025-04-02 19:58 ` Ingo Molnar
2025-04-03 0:38 ` Josh Poimboeuf
2025-04-03 2:57 ` Bagas Sanjaya
2025-04-03 7:48 ` Josh Poimboeuf
2025-04-04 2:39 ` Andrew Cooper
2025-04-04 19:30 ` Josh Poimboeuf
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