From: Sean Christopherson <seanjc@google.com>
To: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Jim Mattson <jmattson@google.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/6] x86/bugs: Use a static branch to guard IBPB on vCPU switch
Date: Wed, 26 Feb 2025 17:42:09 -0800 [thread overview]
Message-ID: <Z7_C8a9oGp8lskhh@google.com> (raw)
In-Reply-To: <20250227012712.3193063-5-yosry.ahmed@linux.dev>
On Thu, Feb 27, 2025, Yosry Ahmed wrote:
> Instead of using X86_FEATURE_USE_IBPB to guard the IBPB execution in KVM
> when a new vCPU is loaded, introduce a static branch, similar to
> switch_mm_*_ibpb.
>
> This makes it obvious in spectre_v2_user_select_mitigation() what
> exactly is being toggled, instead of the unclear X86_FEATURE_USE_IBPB
> (which will be shortly removed). It also provides more fine-grained
> control, making it simpler to change/add paths that control the IBPB in
> the vCPU switch path without affecting other IBPBs.
>
> Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
Acked-by: Sean Christopherson <seanjc@google.com>
next prev parent reply other threads:[~2025-02-27 1:42 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-27 1:27 [PATCH v2 0/6] IBPB cleanups and a fixup Yosry Ahmed
2025-02-27 1:27 ` [PATCH v2 1/6] x86/bugs: Move the X86_FEATURE_USE_IBPB check into callers Yosry Ahmed
2025-02-27 1:41 ` Sean Christopherson
2025-02-27 10:12 ` [tip: x86/bugs] " tip-bot2 for Yosry Ahmed
2025-02-27 1:27 ` [PATCH v2 2/6] x86/mm: Remove X86_FEATURE_USE_IBPB checks in cond_mitigation() Yosry Ahmed
2025-02-27 10:12 ` [tip: x86/bugs] " tip-bot2 for Yosry Ahmed
2025-02-27 1:27 ` [PATCH v2 3/6] x86/bugs: Remove the X86_FEATURE_USE_IBPB check in ib_prctl_set() Yosry Ahmed
2025-02-27 10:12 ` [tip: x86/bugs] " tip-bot2 for Yosry Ahmed
2025-02-27 1:27 ` [PATCH v2 4/6] x86/bugs: Use a static branch to guard IBPB on vCPU switch Yosry Ahmed
2025-02-27 1:42 ` Sean Christopherson [this message]
2025-02-27 10:12 ` [tip: x86/bugs] " tip-bot2 for Yosry Ahmed
2025-02-27 1:27 ` [PATCH v2 5/6] KVM: nVMX: Always use IBPB to properly virtualize IBRS Yosry Ahmed
2025-02-27 10:12 ` [tip: x86/bugs] " tip-bot2 for Yosry Ahmed
2025-02-27 1:27 ` [PATCH v2 6/6] x86/bugs: Remove X86_FEATURE_USE_IBPB Yosry Ahmed
2025-02-27 10:12 ` [tip: x86/bugs] " tip-bot2 for Yosry Ahmed
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