linux-kernel - Re: [PATCH 04/23] KVM: x86: Add IBPB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230826154922.mdmjzwqwdgufb3y4@treble>
Date:   Sat, 26 Aug 2023 08:49:22 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Babu Moger <babu.moger@....com>,
        Paolo Bonzini <pbonzini@...hat.com>, David.Kaplan@....com,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Nikolay Borisov <nik.borisov@...e.com>,
        gregkh@...uxfoundation.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 04/23] KVM: x86: Add IBPB_BRTYPE support

On Fri, Aug 25, 2023 at 11:15:49AM -0700, Sean Christopherson wrote:
> On Fri, Aug 25, 2023, Josh Poimboeuf wrote:
> > Add support for the IBPB_BRTYPE CPUID flag, which indicates that IBPB
> > includes branch type prediction flushing.
> 
> Please add:
> 
>   Note, like SRSO_NO, advertise support for IBPB_BRTYPE even if it's not
>   enumerated by in the raw CPUID, i.e. bypass the cpuid_count() in
>   __kvm_cpu_cap_mask().  Some CPUs that gained support via a uCode patch
>   don't report IBPB_BRTYPE via CPUID (the kernel forces the flag).
> 
>   Opportunistically use kvm_cpu_cap_check_and_set() for SRSS_NO instead

"SRSO_NO"

>   of manually querying host support (cpu_feature_enabled() and
>   boot_cpu_has() yield the same end result in this case).

Sounds good.

> Feel free to take this through tip if this is urgent enough to go into 6.6,
> otherwise I'll grab it for 6.7.

Ingo grabbed all the patches except for the two KVM ones, so I think
he's expecting you to take them.

> Acked-by: Sean Christopherson <seanjc@...gle.com>

Thanks!

-- 
Josh