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 7639C194C95 for ; Mon, 2 Mar 2026 22:48:23 +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=1772491704; cv=none; b=dqCJd4ARMAK4bYHUlegML/dAruliCosTGHyB9w3629br2IvGZ2uzCLhloW5D5aWHZB6hTYIXQb8nOkM821GW53Cnt8lXbPA/7O7byfZs3/yYJtcfodvFQ8Gt5n2immqoGO1lQKDiJOtRWdmLwet/SK1EGH86F9k/TloYoi3tZnQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772491704; c=relaxed/simple; bh=0UkKBP3tbA5m+vfGf0CgmiUvMch83YvZUflHAoNHaDs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=nL816KSdJDPguYquFzy7Qut8676WwrsAcQtqrFUOZBum50Zl7O0nECWCShGd0p/X9vdRSJxMNdaL40Yhw8pENoi1gKT5uuvowdq5Se3pc6Ald/eSDPmTl5fMyGQuRqVmA9GyzpDbeQtYl36NGHCffOppKbtlwzPD0gwpg3w9Jqk= 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=H4fbPVni; 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="H4fbPVni" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-35982c5940cso1523563a91.1 for ; Mon, 02 Mar 2026 14:48:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1772491703; x=1773096503; 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=tXdycAUhqH01yNE4P3PLW9cPG6IWEHVkJ1VuHv/+FFM=; b=H4fbPVniIcjA2Zj/6gYS85yuAR5LGtkhq88NVF73+9KJ1ojRveFFdWKaDfxH1aHCgc Vq/+Lu7KhsyVaabq2v/KjDHlPQLNm0k6NB3BRNCNcoVYSbHwENXenso/e9r8i6VdJHRL 44bQcFhw/cCthvShRSOAzPsTJRDAP1tE6KxgS348dRUsdGEPUf7CkNk5sB9TX3QQ9L6p x1QDcf4FvsispuQkps3wQKPvb6UNVFJO5Kcb8Xr5yZjlERJDe/LdD64jYraMYT2hR/k+ 2xgBbD47AcFtYxGQuWMLp2DRVWSsu2A1DnOd8TIKOGjT2CeIwVF2tH4QUHm/hlXhPB7j 9XPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772491703; x=1773096503; 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=tXdycAUhqH01yNE4P3PLW9cPG6IWEHVkJ1VuHv/+FFM=; b=Zr7jfN/WxyAbMbjzBpzNP+u0yf1MADHE1HJLPfRiDrRumGO8FTiBhveKXoDekFsSF4 DUCIyDoPUpXNlA1I8Cd46Xz/O92dlE0JbRvYnxQPZL2CW29oXyTpDo58zSrbqOiA5XWw KWA7bRC9qInO/64WaJOAg9xF9khes1SAQCNYZrrkfcgz7ZD7IEh9E5c+OdDcT18k9mr5 su7YXz+hefIgXcw5n7B3ChkbiNuUZhj+sQoZ9rOyUu/6+aXphwQm/cq1MAwvhmVW7cfi 6dvPjhQ8JpcdsDvPyxcMZfnMmi05Yhv57gJ3AQcEVB5yDmpDz0vUneJQSsWfbCxSlPF6 479A== X-Forwarded-Encrypted: i=1; AJvYcCUIAnOB0IfJIhZuA0kgNmjzBk86TAhDxrNUtgkrcQy8YRElB1jk0yFDT84vfUB5hgr8i5Rd9NyEhvKUUl4=@vger.kernel.org X-Gm-Message-State: AOJu0YxdgkeVC23WZthUFGjYEtssBDA+DmIeybW6zV0pPK97HrtgddlI VppRq0fchVOWDT/cr604YyYT+aUsR9thSBvgbcbk+l20Mi40owOr77t3w4G1jIQEq5DRTlgtkmO EbcYPrA== X-Received: from pjao9.prod.google.com ([2002:a17:90a:1689:b0:359:877f:98db]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:588c:b0:34e:630c:616c with SMTP id 98e67ed59e1d1-35965ce42fbmr10435047a91.31.1772491702576; Mon, 02 Mar 2026 14:48:22 -0800 (PST) Date: Mon, 2 Mar 2026 14:48:21 -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: <20260209195142.2554532-1-yosry.ahmed@linux.dev> <20260209195142.2554532-2-yosry.ahmed@linux.dev> Message-ID: Subject: Re: [PATCH v2 1/2] KVM: SVM: Triple fault L1 on unintercepted EFER.SVME clear by L2 From: Sean Christopherson To: Yosry Ahmed Cc: Yosry Ahmed , Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Fri, Feb 27, 2026, Yosry Ahmed wrote: > > > What if we key off vcpu->wants_to_run? > > > > That crossed my mind too. > > > > > It's less protection against false positives from things like > > > kvm_vcpu_reset() if it didn't leave nested before clearing EFER, but > > > more protection against the #VMEXIT case you mentioned. Also should be > > > much lower on the fugliness scale imo. > > > > Yeah, I had pretty much the exact same thought process and assessment. I suggested > > the WRMSR approach because I'm not sure how I feel about using wants_to_run for > > functional behavior. But after realizing that hooking WRMSR won't handle RSM, > > I'm solidly against my WRMSR idea. > > > > Honestly, I'm leaning slightly towards dropping this patch entirely since it's > > not a bug fix. But I'm definitely not completely against it either. So what if > > we throw it in, but plan on reverting if there are any more problems (that aren't > > obviously due to goofs elsewhere in KVM). > > I am okay with that. > > > > > Is this what you were thinking? > > Yeah, exactly. Nice. No need for a v3, I'll fixup when applying (it might be a while before this gets any "thanks", as I want to land it behind all of the stable@ fixes).