From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f174.google.com (mail-yw1-f174.google.com [209.85.128.174]) (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 C6FB1283CA3 for ; Mon, 3 Nov 2025 14:10:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762179009; cv=none; b=L/N8jeZl/wSeQW+lMqVLv8RcFRMVxfx7oJobizizdSyUEe/z/lR6nbJFaQ+9cuaJYfsBf7tAxHQtKav0Xa8hdbzw2zAyfFlkgKn4OldfQX+T5yGO/wVpyaBbPHz2u6JgSYEUEZHsGM387j1X226zjTxMga3IgJfqljgedekfJDA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762179009; c=relaxed/simple; bh=kvR+F866SCLceHUacVTlInqOmhhQYvk+JX3lcueuQxo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=TBDBVAf5c0DeUNsspXJXWVBCyTdV649e3nRuOpIcfU1q6cJF8MoNcPC5/duKglJBQCTJLxYWaQ1HO5uj/mCawO9a4CNxicwSJdUQ1u5Wx3+4LvkQXiz4cuG/vOYQRzXMo6x/BiFuyoGYrd81lhpsAmp3CxMm9g07PGx+E/7NKOY= 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=hKkidALW; arc=none smtp.client-ip=209.85.128.174 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="hKkidALW" Received: by mail-yw1-f174.google.com with SMTP id 00721157ae682-7867497ad2fso14566387b3.0 for ; Mon, 03 Nov 2025 06:10:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1762179006; x=1762783806; 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=69ZIdxIDNMyXZ/xRq3HrmYW4BOl2xzIyC5pgSkkI/HU=; b=hKkidALWt0Ysxm6eappFrc2IUZQmlAhBeXLwc7nIGt29/xwqEXTIha3lJoEdTndQZq Mh8TQ4IoGXvLxCSpb3+CniWyhHlyREK/trjnDptB+WMxZ5ZGOTTCi1Y1V/hjUvZLa7om L4voJnSt1gwuqoe63K2L+ynEvfeFVKXIuDL8ZyLNb3bZeIOP1bpkAY5OtM6zumUfn3EZ oUb23wT+c1CgVsdnjIiypTX4Tc9UDLlWa1bpcMiIitlrqCPfKQfdtKwMFs2+chaoXXhy Fr5EbmZHzGEfkL22bLp9TvgCO97jHrwgDYXaYJF3Zf4u4QJKUlmhyX9J7kRMZ1jFAOMn 7ttg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762179006; x=1762783806; 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=69ZIdxIDNMyXZ/xRq3HrmYW4BOl2xzIyC5pgSkkI/HU=; b=VldaUfU7qZhcEHBa424vVwW7kKX2/AxLxfdN/XUrnAfiJgWV8DWbvPGHd2/5h+VZ22 aOzvcQFyWAp+VoI6GS8CqXz2Oe/2WaMho31l5GKMTWGJU4bHcfj9DoMIgC2v/5AQyWoe fIWnnuX7xG9up9L4/cFhX7Ydej3OioanfiMmgjC0adFkTi6pV7ONTqp3VYKKGYMDQyoq v9ACQCKTUFy4AOCQTzuowRBr10dNR/hKw+XR/ad6QUuStEuPstTHDAAeEHQGr+hlmpzk Z6RChptn1JCTNOHzMhVLBd3681NEyVWWJUNSpuaQqpQo3phQbBeuOXl/X0irpyM6LBXc /V1w== X-Forwarded-Encrypted: i=1; AJvYcCUiM62LKqv4o6BQTMjDdO9MZOWFIT6yQitZ7wzN5aYqtTQPNtLkZIy/fuRrueLBhPNuZ9jtmmRkI4yi7Ug=@vger.kernel.org X-Gm-Message-State: AOJu0Ywq9uRWPfDBDXbEnCrq36XTXteZkmQFhZIOJRn9l302PjMSV8pw UKwTot/nRTCEn33NQ0xiXGCqHU9doOA24/n5jHZJluilWSeBOhCjIHQa X-Gm-Gg: ASbGncuAly4xk/1y65BKc9Rooehzu0s4fOst05ndw8VZb2Pf7xCOzetwjoYllTx1+iP IyHati4k8vksw1RxQZuQ+sACgRBSKJo7cV+fiRlto9EJ1bQKZfx0MyO67bAFWQ1zNQ+Kd/zPRv/ Zt4lJy8hCXHOJX858lGfdte357n8EoRfEkqb5KAb3m7nVmIe20zo0qF+06tD2TmQmkkK9eaYw5X TdgBqTjWRWZwBuVThxHCaleVS7qqZ1u4DCZyDYfmviSROLi5GY6ANuN0OQTAPhGmMnR7eoGoja6 EDX2589ZA/8Bf8hmU6BOE++8mOPylGowS/uliTpThj9xLuUWuaEB9f4EwgqOTZ/Nc6m/D3p4voT czTZKYe0eGg08ZxkxyzM+uCY1srjSu8c+ApSMAkID97AA3cp53Dk1LGJRiR/K1f4CqNQJGmwU41 tHGHMhfxBVhw== X-Google-Smtp-Source: AGHT+IGD6jontoCLUBayhIbAtJav+5thxwXtcpelKDJ0KvQPHTZJga3plVryThbhDNEe0gpi2QFgWA== X-Received: by 2002:a05:690c:4984:b0:786:706c:7e8d with SMTP id 00721157ae682-786706c8b65mr43383617b3.27.1762179005542; Mon, 03 Nov 2025 06:10:05 -0800 (PST) Received: from localhost ([2a03:2880:25ff:4f::]) by smtp.gmail.com with ESMTPSA id 00721157ae682-786920630a4sm837387b3.55.2025.11.03.06.10.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Nov 2025 06:10:04 -0800 (PST) From: Usama Arif To: dwmw@amazon.co.uk, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, ardb@kernel.org, hpa@zytor.com Cc: x86@kernel.org, apopple@nvidia.com, thuth@redhat.com, nik.borisov@suse.com, kas@kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, kernel-team@meta.com, Usama Arif , Michael van der Westhuizen , Tobias Fleig Subject: [PATCH v3 0/2] x86: Fix kexec 5-level to 4-level paging transition Date: Mon, 3 Nov 2025 14:09:21 +0000 Message-ID: <20251103141002.2280812-1-usamaarif642@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This series addresses critical bugs in the kexec path when transitioning from a kernel using 5-level page tables to one using 4-level page tables. The root cause is improper handling of PGD entry value during the page level transition. Specifically PGD entry value is masked with PAGE_MASK instead of PTE_PFN_MASK, failing to account for high-order software bits like _PAGE_BIT_NOPTISHADOW (bit 58). When bit 58 (_PAGE_BIT_NOPTISHADOW) is set in the source kernel, the target 4-level kernel doesn't recognize it and fails to mask it properly, leading to kexec failure. Patch 1: Fixes the x86 boot compressed code path by replacing direct CR3 dereferencing with read_cr3_pa() and using PTE_PFN_MASK instead of PAGE_MASK. Patch 2: Applies the same fix to the EFI stub code path. (Done in a separate patch as Fixes tag is different). Co-developed-by: Kiryl Shutsemau Signed-off-by: Kiryl Shutsemau Signed-off-by: Usama Arif Reported-by: Michael van der Westhuizen Reported-by: Tobias Fleig The patches are based on aaa9c3550b60d6259d6ea8b1175ade8d1242444e (next-20251022) v2 -> v3: - Use native_pgd_val instead of pgd_val to fix broken build with allmodconfig. I wanted to keep the code between pgtable_64.c and x86-5lvl.c consistent so changed it in both patches (Borislav Petkov and Ard Biesheuvel) - Commit message improvements (Dave Hansen) v1 -> v2: - Remove patch 3 to fix kexec for source kernel in 5-level to 4-level transition where the 4 level kernel doesnt have patch 1 and 2 (Dave Hansen) - Add include for asm/pgtable.h to fix build for x86_64-allnoconfig (kernel test bot) - Use native_read_cr3_pa and for both paths (Ard Biesheuvel) Usama Arif (2): x86/boot: Fix page table access in 5-level to 4-level paging transition efi/libstub: Fix page table access in 5-level to 4-level paging transition arch/x86/boot/compressed/pgtable_64.c | 11 +++++++---- drivers/firmware/efi/libstub/x86-5lvl.c | 4 ++-- 2 files changed, 9 insertions(+), 6 deletions(-) -- 2.47.3