From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 B25E61A9B58 for ; Tue, 16 Sep 2025 00:26:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757982406; cv=none; b=EhP9njKgbKQF+x5ZyxCDuC+d9HSw3LdRbdER06z309RDYwXhnQG1HjkvkJSxCbls+Tdf8nicg++paQxS2BTmW8Od04QkCA17Py09JNgQzOietJEp2RbOEdNiQ4O2MBNmNbiqKABnJDui0kKS/34vIWm4we/05yswxw2GxfwHrf4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757982406; c=relaxed/simple; bh=cnvhbFmTcyALwq0L6KJioIroByTdgWEgWbFNzgvWNfQ=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ljhkcbd0pNMaoFNrg6cGCS9nPSJxsYE/u1F/r4x3ApnEBlJs3ozwJBlgvJ7R41Fo6zjpySny3PkNn+Z5Q3l7loYLlRQ69taZA2G89v2iHWAUCS+b+aNqmCOmbAFgVJEnPTuMZ8X0mSG5zh6i1HLDFgGHZd1/UY+44Y4msCGU5xw= 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=hO1Do+cq; arc=none smtp.client-ip=209.85.214.202 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="hO1Do+cq" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-24457f59889so49124645ad.0 for ; Mon, 15 Sep 2025 17:26:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1757982404; x=1758587204; 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=5HErJT+zZxpaz3D/5r9TYIS9HH59s5D9HZXheG5gZRM=; b=hO1Do+cqajGpmDSBn0olUrkMBMH4NCy9veFMxrK9ew4Fu/3BwGIkiVPCMHvbjUJcV3 vrsbZ4ctBbWNS28fY2SDA1oQRaV8x3esOnGYbY4TxW3Q7oIDSkA0RnaKXmboIjClI0nT RjA+qdxLuQeRouGLf3U1w8Qmpu8eE0HGQtGyHp8WKC2gvOfXqTRtI68JobzKHLVLK35M CvR6ALwqFWoK4J+MWgsiBGUDtSgMuJ0m1KfsQ8ZaICMYiw0Gls2D+ZABkBKuezbnHMFJ wzm5zIAdBveEh92sGVxWO0nfV8FYRHCwwvm3qoLTQ4BKGGmCZECfVAjmQjTq86RbrEd0 uyjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757982404; x=1758587204; 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=5HErJT+zZxpaz3D/5r9TYIS9HH59s5D9HZXheG5gZRM=; b=cA24FASPOD6O2gg6KUNn18S3ftYvDOr4uBWsNKlNgWjq3wooTsoNpDrjjyKRlJ9H3V FiDR7JEjNPEORDKOyqvaZyiV4JoMjI/nQyTRpzFNAlmYYbckyFwjGb6mww1d7y1Vopmo wWRqZBfvrp6UAesD3AdAogEljnX1CdAxqUJdZ7oeq9JRHVaeFZywHebeu3hi8YdGhE6e 6cfTHzF9BspaBnovsb2oZFHNYrD73UGTn5jrGQ3oafRb7nrtIHtQ5QFVu5SPoScNg/Lz guhv9ZcP2vhYY4OL39jL97YFXQTPIgpN2HpHZ/I5jlICD1rF0CukX7/fKXve5FXmByaS 5G5w== X-Forwarded-Encrypted: i=1; AJvYcCVaJ6xjCm6e4tPu+3eeUgvmWlhoxVLiKLwfw21KNEotv7GzW6DzK2KMS+Qt3L1Sl0LfpL4uxmdYPSSY3qs=@vger.kernel.org X-Gm-Message-State: AOJu0YxH0poqUei4DyP3gFltIh/Go6QwTRztbhGq2zn+CUrvXRVrOEYn XvF8k2myc8WJrYGpaJkrj7z0XYEkaM2ivpJG83YojjEm9Ob8amxz9QKuwlI4Nnu9XnoMcR/kniR 8SxAMig== X-Google-Smtp-Source: AGHT+IEXcOlqEynPdUtfk1M9vVESGR/13AAj4MidAL8m/pOelS2mXMYUIsm19xBmBwuCgDsJXDfsGCPjiLQ= X-Received: from plbkl13.prod.google.com ([2002:a17:903:74d:b0:264:1805:b649]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:1acf:b0:25f:9682:74ae with SMTP id d9443c01a7336-25f9682760bmr131062305ad.29.1757982404046; Mon, 15 Sep 2025 17:26:44 -0700 (PDT) Date: Mon, 15 Sep 2025 17:25:35 -0700 In-Reply-To: <20250828005249.39339-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250828005249.39339-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.384.g4c02a37b29-goog Message-ID: <175798202141.623675.2546293939402072087.b4-ty@google.com> Subject: Re: [PATCH v2] x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Gonda , Vitaly Kuznetsov , Tom Lendacky , "=?UTF-8?q?J=C3=BCrgen=20Gro=C3=9F?=" , Korakit Seemakhupt , Jianxiong Gao , Nikolay Borisov , Binbin Wu Content-Type: text/plain; charset="utf-8" On Wed, 27 Aug 2025 17:52:49 -0700, Sean Christopherson wrote: > When running as an SNP or TDX guest under KVM, force the legacy PCI hole, > i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC > via a forced variable MTRR range. > > In most KVM-based setups, legacy devices such as the HPET and TPM are > enumerated via ACPI. ACPI enumeration includes a Memory32Fixed entry, and > optionally a SystemMemory descriptor for an OperationRegion, e.g. if the > device needs to be accessed via a Control Method. > > [...] Applied to kvm-x86 guest, thanks! [1/1] x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP https://github.com/kvm-x86/linux/commit/0dccbc75e18d -- https://github.com/kvm-x86/linux/tree/next