From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (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 4680A30E856 for ; Mon, 9 Feb 2026 21:19:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770671983; cv=none; b=kosovZ2QAtZrNS+Rc+3ur+ncZwATt9fRqubHw8+KHc3dz48gicVUpKoIvE9IO81T7jb9yEcZp25UzHopYzM9POJkuynnXaEa+SlNpBAChqLvddQzk9ODSPOi+d0waRkFzS7cO+u9AXDAzZyekT/zjjvZeLbz6iTy8pWA6Of9BjA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770671983; c=relaxed/simple; bh=Y4LgqKz4HV88xl/cRgqz4S3s9scHVfLf5Jfxz1PMyI0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Dep4ax9JZohZ2h4G4ieHLqTerhpY9R1nob2kxUIHaQYhifMhrsTjrD+8lkYfbkSVcsv7vMAQeaR1bh5wlTsvk1dvsZNARTtNS61ut08nBTHVvGcd6OGr22yiw2WH9aq1nYwCPYHdwrImFLafbSx89sDkLqJDa5S5n0R2Gg+x9Sw= 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=pAY/Dpn3; arc=none smtp.client-ip=209.85.215.202 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="pAY/Dpn3" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-b630b4d8d52so2195441a12.3 for ; Mon, 09 Feb 2026 13:19:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1770671981; x=1771276781; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=0tmTg43Su2XIUd3mvKAV1dcrfYudwS1bYBY0CWZrNEo=; b=pAY/Dpn3sSg+MgA5b94gWuob5ZFfYpoFjVL8/Uy0IFEKlGb+o+g+1ZmnAClLrc64t5 6h3ch+0oKuVGMUI0Q4ZzmhzQBYEJnlBhFLMGR/ZAwvU5XxZQ33OSFM0jFWOEsdQyL/n8 Q3LoKMTMxAvXC/qXVC3kXz26eujzSdcNnHTP3XUQk8oIIM+ahzvBdtJx4vy0aGGjJcZo keao3CH5IWxQjmUzQDTZW+zJ7RupFT3Jjh8M6YfC+KSdl77AJw3p8RTcL9GWAInn5RJg djlu0L3b5OxQR5drlsYrjIPQhPcnP4yz7oUn3dyXyC4SFulLGWfC8FcMUwYXhzKnVLHx lTcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770671981; x=1771276781; h=content-transfer-encoding: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=0tmTg43Su2XIUd3mvKAV1dcrfYudwS1bYBY0CWZrNEo=; b=BKTcO7kYa0gWg413aBuJPF87AItfLzscOJQSKT/TNSbeCp+eazNq47tLFNfQ60Hcjv Tf7G8nmR4EVyPefFTYmWcbQEZZc7Km7Gi4ewWZnyAdcBXndeqZZhS2LG0mYCCSojqOg4 9COLkAvaoQy7rYssImk79G6UODLU12DyASS/XSzx9Pv4lGiU/el3enRjRQwB/tGXWaWM YGCIJgbWvnrv1Kapm7Bafovk9FSaeEROqaXgwGMi83M/1px3BBrMnivDXSLRxXLW+PC1 5yV/W7M9zEmwmWYAcsk1ZiHLSA15uCSsAyZexxRx0PnksVJKtgk/eEWDWFvqOFyTxQdy dQVQ== X-Forwarded-Encrypted: i=1; AJvYcCVUVjq6fxk+P0xMnulPL1wyPifcymYav/TCD5kA07KeKb/iW7AzMrgLNLjVSS+8fhF+TY4MI9MUOfo3sH0=@vger.kernel.org X-Gm-Message-State: AOJu0YxlqK41oH/MwWscs4K773dVLJ81cUeDAUNXoKu4OcWeSKkmPQJu Lyoqu+nreNFXcFHsLxDfx0BpnLW3r0VTuzVVAgZhG39kujMiOFKNxOUGIFXlNcCkQPIwFEHPriA Q1TPJJw== X-Received: from pgbfm15.prod.google.com ([2002:a05:6a02:498f:b0:c63:58d6:3345]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:2e18:b0:38d:f08d:b349 with SMTP id adf61e73a8af0-393ad33a4c4mr12100704637.43.1770671981490; Mon, 09 Feb 2026 13:19:41 -0800 (PST) Date: Mon, 9 Feb 2026 13:19:39 -0800 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260207041011.913471-1-seanjc@google.com> <20260207041011.913471-5-seanjc@google.com> Message-ID: Subject: Re: [GIT PULL] KVM: x86: Misc changes for 6.20 From: Sean Christopherson To: Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Mon, Feb 09, 2026, Paolo Bonzini wrote: > On Sat, Feb 7, 2026 at 5:10=E2=80=AFAM Sean Christopherson wrote: > > - Add WARNs to guard against modifying KVM's CPU caps outside of the i= ntended > > setup flow, as nested VMX in particular is sensitive to unexpected c= hanges > > in KVM's golden configuration. >=20 > Possible follow-up: does it make sense to sync kvm_caps.supported_xss > by calling kvm_setup_xss_caps() from kvm_finalize_cpu_caps()? Ha! I did that in v1[*], but Xiaoyao didn't like that it hid the XSS setup= , which very technically aren't part of kvm_cpu_caps. For the current code base, t= he pros and cons of each approach seem to largely cancel each other out, so I think= my vote is to keep things as-is for now, and revisit things if/when we end up with = more common code that needs to run right before kvm_finalize_cpu_caps(). [*] https://lore.kernel.org/all/20260123221542.2498217-2-seanjc@google.com