linux-kernel - Re: [PATCH] KVM: x86: Unify cross-vCPU 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] [day] [month] [year] [list]

Message-ID: <174622231823.882065.2543559051221676218.b4-ty@google.com>
Date: Fri,  2 May 2025 14:50:53 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jim Mattson <jmattson@...gle.com>, x86@...nel.org, 
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Unify cross-vCPU IBPB

On Thu, 20 Mar 2025 01:37:59 +0000, Yosry Ahmed wrote:
> Both SVM and VMX have similar implementation for executing an IBPB
> between running different vCPUs on the same CPU to create separate
> prediction domains for different vCPUs.
> 
> For VMX, when the currently loaded VMCS is changed in
> vmx_vcpu_load_vmcs(), an IBPB is executed if there is no 'buddy', which
> is the case on vCPU load. The intention is to execute an IBPB when
> switching vCPUs, but not when switching the VMCS within the same vCPU.
> Executing an IBPB on nested transitions within the same vCPU is handled
> separately and conditionally in nested_vmx_vmexit().
> 
> [...]

Applied to kvm-x86 misc, with the online=>possible change split out to its own
patch.  Thanks!

[1/2] KVM: SVM: Clear current_vmcb during vCPU free for all *possible* CPUs
      https://github.com/kvm-x86/linux/commit/1bee4838eb3a
[2/2] KVM: x86: Unify cross-vCPU IBPB
      https://github.com/kvm-x86/linux/commit/54a1a24fea19

--
https://github.com/kvm-x86/linux/tree/next