From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f195.google.com (mail-pf1-f195.google.com [209.85.210.195]) (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 72A82303A03 for ; Thu, 16 Oct 2025 08:19:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760602754; cv=none; b=X4RdANv4A3nTndyusBhCRt/5gDcWDbbXeFluOd/hFkAD9cRZdFeFwhEoqIr1cexryYkWm0K+KndmF97myHmmE6qxfnEU2X2Il3z5HtY4w6P7f94gxA9caHzoP1jXJ7gpzahMy1qNAChXBzNjscUqAwNHVdyBlTOJ/qzJx0UxoA4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760602754; c=relaxed/simple; bh=8cVKadBnNqQelkNfiWowVZi0bC+Sd9kYaA6vARK1Cdo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=WtWAm8U7Q/6Ppjs9Tri++Hs0tZnMA6WBCbO1qyiejnai2eUBMRtlQMdyxxtL6fxO5ceWLAPi1+yeATseYl+6KDBHqAzdb+txnU4CecJd+Q3ljQ9MxbEvI/gc8AokwIMqqnclSDRvrchSpuYdbfpvCk9JTrQe9Zqsr4qfBhluoAk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=MtN+P3+w; arc=none smtp.client-ip=209.85.210.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MtN+P3+w" Received: by mail-pf1-f195.google.com with SMTP id d2e1a72fcca58-79ef9d1805fso452073b3a.1 for ; Thu, 16 Oct 2025 01:19:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1760602753; x=1761207553; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=aNn+teilF/m2S5Y0Gs7r6IivDfLkDWPYH0vOCAjEYEI=; b=MtN+P3+wWuyIoD12cb9U673AUsuJ9teTgGHN7QaTYcDLP58Szno9BTZwSlE+Q3KGea WBs6M4S5eXgjWeMTJzmmfK7evKt1UdODGO6X9m8UEgu4YA1ej0YroElr9zUlsRUp4mL2 jBOWLlFmZi5o/cXVBAaBmET2tKGWruk30pw1NohCNpkYUrteOOt4BWP4/EnKV3V4AFdn 0GFq7RGIT9K9sJFF4URA9rev0l1gHOWekwSsmH+13119og19LTUukaOiFGt+hVR9sgly 78b2ElWXjMTZ0GfiDkL4Ocgp5nW31BvJtYAytZQwnC78BnopDs1Ol6t0Qy0CUJTbrh6M FeaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760602753; x=1761207553; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=aNn+teilF/m2S5Y0Gs7r6IivDfLkDWPYH0vOCAjEYEI=; b=fmR9oN4a9eD+xNexw/6HhBysevPnfNFMI7qLuv9XFbjXyQCAn+x0gmkeSdjKK6/viW Px7+/kueFtLh1DxzJCzpDGymqfQuJ/F/5GDtPwIf6LP42Mgo+deE/gfwOt30zl91N1c8 qtdk6uGER3QCgHO0Cnq4xtnQxyDuK7Ahq9TQzGRyCmsT0Pf4Q8EHwn6BGu1WhZtSirIA W+G7+p1zgPq2mk1gsEJvWS3GFAecEuiKMzpSXHn6Nrh/0K1ZIk8mIXP0NnzUXB3Ks7os dVB7wxW79HHF7RWYITppayG2YI0crOzf0j/5DsAbe8hnM9hilYN772jWZt43dmMf6rML THHQ== X-Forwarded-Encrypted: i=1; AJvYcCXaql2RqhvEoLR6gQemoTVr0y0Z1P2oXVR5DbTSd3LmSVNO6ZZuVBwQhXhrSR8gdo1CC16d1bPVoGg=@vger.kernel.org X-Gm-Message-State: AOJu0YxE3QIiGGyaOH0As1ZsLqoDJ7lAhGGEPqq5saatqL7y/rbRIrFl v3AqYQNRrOV1KdhF0+yQd8HfoxSDnjtTT3XTLg36oK0pvFPGkviYqr4= X-Gm-Gg: ASbGncuoQvD6kzjFqmaCtMruL9v3fsNJobXUN7GeCqSxzaox61ySdTXUwjg9Yqf3tUg hJsfUgJVVz4xCbf28welF/F1FTjSHDnr1xVtf3npgn3jUng+fFEd8YfmKmPtmS1qxuBYjhiEkBR NvD50RQQmxk+iquD4AGBMfEno3gmm+peNMYiEDhUUwg9mZGbyWZWEfbkQ7yzZRpuo8lCt8X/NAX 3Y6g1KyL2sY1bcnH+HE6wzCGXQGsyb4C3ZRImun95gC7LZzdnQbeB47GWtSBeXAAJLacBDLTXoS DZvH+kR6jbDDt7HR7MxAXFUjmANXP+6f+l8/h8OH67NEGpkoWvpx99YxRehWlle7CGkJWPFWFf6 beaq7yvkG6ZaANiE391dMIwAjbSpamzWc/Nz0D7625uCJLDNxhHQEQDDR05OIdBdxDw/uK4f3+B Y6zHG90w== X-Google-Smtp-Source: AGHT+IEsXtrMGo2lro2BmjiMPP+RR1rwWwgZU12zOACeOUGh+HQJMzgQiRxJdGRfDEBihQlF/0H8Sg== X-Received: by 2002:a05:6a00:3d54:b0:781:be:277e with SMTP id d2e1a72fcca58-7938513618fmr35273590b3a.4.1760602752628; Thu, 16 Oct 2025 01:19:12 -0700 (PDT) Received: from kotori-desktop ([139.227.17.209]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7992b065ac2sm21232797b3a.16.2025.10.16.01.19.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Oct 2025 01:19:11 -0700 (PDT) From: Tomita Moeko To: Lukas Wunner , Bjorn Helgaas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" Cc: Tomita Moeko , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] x86/pci: Check signature before assigning shadow ROM Date: Thu, 16 Oct 2025 16:19:00 +0800 Message-ID: <20251016081900.7129-1-tomitamoeko@gmail.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Recent IGD platforms without VBIOS or UEFI CSM support do not contain VGA ROM at 0xC0000. Check whether the VGA ROM region is a valid PCI option ROM with 0xAA55 signature before assigning the shadow ROM to the default PCI VGA controller. Signed-off-by: Tomita Moeko --- Changelog: v2: * Use memmap() instead of iomap() as the shadow ROM is copied to RAM by BIOS * Only map the first 2 bytes for the signature check. Link: https://lore.kernel.org/all/20250406090835.7721-1-tomitamoeko@gmail.com/ arch/x86/pci/fixup.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c index 25076a5acd96..10dce90e0e00 100644 --- a/arch/x86/pci/fixup.c +++ b/arch/x86/pci/fixup.c @@ -357,6 +357,18 @@ static void pci_fixup_video(struct pci_dev *pdev) struct pci_bus *bus; u16 config; struct resource *res; + void *rom; + u16 sig; + + /* Does VBIOS region contain a valid PCI ROM? */ + rom = memremap(0xC0000, sizeof(sig), MEMREMAP_WB); + if (!rom) + return; + + memcpy(&sig, rom, sizeof(sig)); + memunmap(rom); + if (sig != 0xAA55) + return; /* Is VGA routed to us? */ bus = pdev->bus; -- 2.51.0