From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8AD336C0C8 for ; Tue, 17 Feb 2026 15:37:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771342626; cv=none; b=owVNeSlHAmpWcx21OPMVIGMBpCsyisPvyO9gf5jHd9+MVy3D/nPd1ZIoX3POGG4nC0ZaTKnt8vh9JoAelzrm8+l38+5bsNy+YxDhxWg67f91PrOadpzMPPY773CjpgCKRnGovJgPQjZq+iMFHUi8vri5NQR9/e2lsL6wez+G39I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771342626; c=relaxed/simple; bh=TphFOmg5HX47PxcNF0aXXEWkqBDunsNyhd0Q+qPBanw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=pzajXvBKcBj14usEFTKjmLv0uUqoL4uvYBWY2XYqc8VDUfYoadKbouXOkcuoi8yNk53YC0KrUFiw3xgVrAh0BBreJJm2OCmbujvMtvGPGxrppesQSasaP7BwP0bIaOGJEBm+8sxr//ur2O+QJqVj1jJz8DgLlJyE4q0RRrK88EY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=R+oT34JJ; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="R+oT34JJ" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-35449510446so4177684a91.0 for ; Tue, 17 Feb 2026 07:37:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1771342625; x=1771947425; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=WTxcxfGLHAARjNrp3hq8o4WxaX/qmkiZ+kEfmNnUDlY=; b=R+oT34JJ8+26th6EN6YO/RzQry07+uSnZfEI3LqHol5B4zzrNVScqYOuLW0MwX4Njv 30xMQKsSFC0g+cZggH9xsDkFgMmMrzaFIqYQ7VOcYbIjC679eU1EBApuWVUkkY26z7zU jXUQwgdl3vQpd+Io//Dhjw4Ud40PTmvPXZIdzveW8u+1HgcYOZgyAzxxFyv0gfkScub4 tSNhTGi64vYTuVpwAOU/lvW13KzIlye/91zyQXB/A3OCiFkdj1okps3tUVdU0NnwLUmC Hsw+dAT7NXAbkR91EoTR2NOjk4zfverLyjhxLUUGv1NJtpUERblVt7vRQZGd66r3hJiA VDYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771342625; x=1771947425; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=WTxcxfGLHAARjNrp3hq8o4WxaX/qmkiZ+kEfmNnUDlY=; b=O89RyCmQto3SmNarP44+Z36lwSpscucr8q4oAVAt1B9Uz1i9hSlEqCIQvBziIHUOdJ aaBeK8EMFvvI3xCbSN6vmjY6E/5012CL+IeVwJuFdiYL5UrVdsxQNCDzpNDzxwzUWPhZ 4H7Hlp1FbDApZI97n+CsBrkdIHXxGn2/cASe006L+Jyo9gTcZ40FLpOyP1CQcXAWospa 851jOhLCIRWcY9MDFs2ZKN+LW7qZDKY2FMzmtLCqBluzksCmY62rUrw2YLS/WwdpeXOZ aedEDBqMPY/FEyVEdJ1TxpjKD+WR1wuv8xd0VSLy+5ViQCyfW65WhcRK/Ta5dNUMf4xv wZAw== X-Forwarded-Encrypted: i=1; AJvYcCXKRu42Ao0lnKOL4PML/8xqp+D5CqgVp54An6zujn8yg1vmdkex9kRGAoo4pk1P9+AwmBk=@vger.kernel.org X-Gm-Message-State: AOJu0Yy4HfNeXfxX//9VpAdvrrdKtTobDpWlowZEkuDPTvz4rXWx0DNG I41b+6lFZLP2HU2c/Pmm0LWFS0Pw3rbhntyIjbtkjY43xMRFdoskZgOfCVH17nd1uVmrhe28fKO OBjK3Ig== X-Received: from pjbjz3.prod.google.com ([2002:a17:90b:14c3:b0:353:d0b3:8611]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:d60c:b0:33b:bed8:891c with SMTP id 98e67ed59e1d1-356aad70cc4mr12681639a91.23.1771342624794; Tue, 17 Feb 2026 07:37:04 -0800 (PST) Date: Tue, 17 Feb 2026 07:37:03 -0800 In-Reply-To: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260215140402.24659-1-76824143@qq.com> Message-ID: Subject: Re: [PATCH 1/3] KVM: x86: Enhance kvm_vcpu_eligible_for_directed_yield to detect golden targets From: Sean Christopherson To: 76824143@qq.com Cc: pbonzini@redhat.com, kvm@vger.kernel.org, zhanghao Content-Type: text/plain; charset="us-ascii" On Sun, Feb 15, 2026, 76824143@qq.com wrote: > From: zhanghao > > Detect "golden targets" - vCPUs that are preempted and ready. > These are ideal yield targets as they can be immediately scheduled. > > This check reduces unnecessary yield attempts to vCPUs that are > unlikely to benefit from directed yield. > > Signed-off-by: zhanghao > --- > virt/kvm/kvm_main.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 61dca8d37abc..476ecdb18bdd 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3927,6 +3927,9 @@ static bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) > #ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT > bool eligible; > > + if (READ_ONCE(vcpu->preempted) && READ_ONCE(vcpu->mode) == IN_GUEST_MODE) This is nonsensical. It should be impossible for a vCPU to be preempted while IN_GUEST_MODE is true. Even if a host IRQ arrives while the guest is active, KVM should set vcpu->mode back to OUTSIDE_GUEST_MODE prior to servicing the IRQ. Even more confusing, the next patch explicitly rejects IN_GUEST_MODE vCPUs from kvm_vcpu_on_spin(). > + return true; > + > eligible = !vcpu->spin_loop.in_spin_loop || > vcpu->spin_loop.dy_eligible; > > -- > 2.39.2 >