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 85FF033BBCD for ; Thu, 5 Feb 2026 23:24:00 +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=1770333840; cv=none; b=Bnf6LHD2J/V2nmKvuWY06Ap44Mh4oSDm2ZwM7f9uzgNW+6fUPKjiABcJJwx52AQyiF1eWTcqX64yGGrM4CJ02vOTwoiTctksxyZwYA2kqWlYb9y8JTF/ns36ggPnUHU+OrHVct4zfwhWzVuNq1LuFIPgkeEVeUGJfKqEPj90JDA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770333840; c=relaxed/simple; bh=kYJ0xbtYMF9eSWTHi1gW1Fy43B/P9OPaa7XaKm1WNzY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=MR4QnWLwjYYcku4qlq8vA//hJokxs0doXwmHzLG+Q3yX85i1JMQpy+uupuVj5QCpDlukvGNztL8+a3NVI2fzECYlC3C8vo32I6ZodddzXiuKyj/8lU530FODIlQW3xhPv5uTAewrr2HzcZxwqicGDZqarLXek7nbfDrEZYSW0/M= 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=sb5fyJXR; 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="sb5fyJXR" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-34c48a76e75so1427000a91.1 for ; Thu, 05 Feb 2026 15:24:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1770333840; x=1770938640; 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=sjrOHBwOAp+rfRNqktTmxKMOj6iLbUuyVutwNWbVhG0=; b=sb5fyJXRwqQhs/nRjbTFG1HV+pm90DN/h41vwLmCHtifIZ6YiiV9RNjjOHzywEurGE zQQ0XP+/MWsaoBQneZpjCZkKJzRqRbs5xcA9o1lY0p52xUyoAicD4WRheN684uil2eN2 0oKZ68/hS+RwpP3V8wyz3TPJH9d2LW9U4zj+DRAp855njdYoVuetRCHd18CS+A+5778D +ZRzf1ZuoIT8X5HCmQXmeJPTMEShU4+XoimJihlciQNdh5JhVhG+bc9GBQmyLv2/Xc8E CREBjfum/NVXsRmF3ybOVsJY4w0tAPfXB0UTZPa+gjUeIYmzNU+bEfXbeXCTRvtuRWyC Oejw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770333840; x=1770938640; 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=sjrOHBwOAp+rfRNqktTmxKMOj6iLbUuyVutwNWbVhG0=; b=pSZa0//rXCXp5E5ukTAHHmkBMicY4BqLcHXXcCa0qLFAZdi2950bBUzruY7BONnpAt YAe2eZbT1YN3PVvWMjyih9lvCdWhyKuxpgyoo/TcuHVLpSx8PEuSWcvf7eLvuerha8Va vb2Orhvymt8CoAPUMCh5ddm/hSpmGa8YP9NQzlb5YgAQlb1zDrysGRkP8Ge2N7lKAMlc Hi32MWI6452pn3AozJUHibVhVjjLHVqwAM0v2fpYURa8OosbuxAdnJPRYk+PmzAYZNY+ BEIXVC8GFCgV0Sj4imSpV04R53qlQ9boduBmKVz7jn/DugVd0Ul8E5QU7tpFKbmS4y7M IB0w== X-Forwarded-Encrypted: i=1; AJvYcCWph9X0buhb3dys48YCIjk06SF6sGpB8TRVdR9A3vxcktARfBbuILFW8oPAksRR1g5qTteUKBmhHXpa+cs=@vger.kernel.org X-Gm-Message-State: AOJu0YxJVoKWqG+kkbl/fUtb4LQionFn6QQwQ+1tOsMI/JXnho/T2H5S cBs9Jo7tu7R/z6jMD1sJKN0l/pAw6qPVpveXhxb8tPRC9da+84we53UBkRxSB0T5FqsH4rp9ITg WEmWWwg== X-Received: from pjed23.prod.google.com ([2002:a17:90a:1157:b0:34c:2f52:23aa]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:28cc:b0:32e:4924:6902 with SMTP id 98e67ed59e1d1-354b3c406ccmr629203a91.3.1770333839918; Thu, 05 Feb 2026 15:23:59 -0800 (PST) Date: Thu, 5 Feb 2026 15:23:58 -0800 In-Reply-To: <20260205231537.1278753-1-jmattson@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260205231537.1278753-1-jmattson@google.com> Message-ID: Subject: Re: [PATCH v2] Introduce KVM_X86_QUIRK_VMCS12_FREEZE_IN_SMM_CC From: Sean Christopherson To: Jim Mattson Cc: Paolo Bonzini , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Josh Hilke Content-Type: text/plain; charset="us-ascii" On Thu, Feb 05, 2026, Jim Mattson wrote: > Add KVM_X86_QUIRK_VMCS12_FREEZE_IN_SMM_CC to allow L1 to set FREEZE_IN_SMM > in vmcs12's GUEST_IA32_DEBUGCTL field, as permitted prior to > commit 6b1dd26544d0 ("KVM: VMX: Preserve host's DEBUGCTLMSR_FREEZE_IN_SMM > while running the guest"). The quirk is enabled by default for backwards > compatibility; userspace can disable it via KVM_CAP_DISABLE_QUIRKS2 for > consistency with the constraints on WRMSR(IA32_DEBUGCTL). > > Note that the quirk only bypasses the consistency check. The vmcs02 bit is > still owned by the host, and PMCs are not frozen during virtualized SMM. > In particular, if a host administrator decides that PMCs should not be > frozen during physical SMM, then L1 has no say in the matter. > > Fixes: 095686e6fcb4 ("KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter") > Signed-off-by: Jim Mattson I'll tag for stable, but otherwise LGTM. It's too late for 6.19, but I'll get it queued up for 6.20 after giving others a chance to react. It'll miss the initial batch of pull requests, but I'll try to send a fixes for the second half of the merge window (I just realized I need to create+send the pull requests...)