linux-kernel - Re: [PATCH v2 3/4] x86/bugs: KVM: Add support for SRSO_MSR

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: <20250108191447.GHZ37Op2mdA5Zu6aKM@fat_crate.local>
Date: Wed, 8 Jan 2025 20:14:47 +0100
From: Borislav Petkov <bp@...en8.de>
To: Jim Mattson <jmattson@...gle.com>
Cc: Sean Christopherson <seanjc@...gle.com>,
	Borislav Petkov <bp@...nel.org>, X86 ML <x86@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	KVM <kvm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/4] x86/bugs: KVM: Add support for SRSO_MSR_FIX

On Wed, Jan 08, 2025 at 10:37:57AM -0800, Jim Mattson wrote:
> Surely, IBPB-on-VMexit is worse for performance than safe-RET?!?

We don't need safe-RET with SRSO_USER_KERNEL_NO=1. And there's no safe-RET for
virt only. So IBPB-on-VMEXIT is the next best thing. The good thing is, those
machines have BpSpecReduce too so you won't be doing IBPB-on-VMEXIT either but
what we're talking about here - BpSpecReduce.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette