From nobody Sun Feb 8 05:29:09 2026 Received: from mail-yw1-f182.google.com (mail-yw1-f182.google.com [209.85.128.182]) (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 A0941305978 for ; Tue, 28 Oct 2025 10:57:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761649058; cv=none; b=tU5v2TH0m/10HTZU0O+n39YBkMm5wrE4XR6UAiz5W9E/yoqQXJqMRCPbHlUAI3usoFxivSTUHue5uXMeutUgbWSWnzMfxvfwcxT3Ktekbh/a3R9D4yIPtUAzfbkQmXNErhDg/wYkJmq17JaSbzE6LONbzttB2hqZIXn/q+3g61M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761649058; c=relaxed/simple; bh=EjZ623Y3caca5aec4q+HisSzkk9SYD6YdSbXcfO0xg8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Niln3whzJzF9xmevFCFVX0VE0CvROURCaA760ghuFdiDMEqQ7AAXvAQNN9jK07HSRKH7/UrfBQnlYHU14yTr62G/WPiwAPIoses5WFWDvtkI939pGv9ZVNIHvjCfHAdEb5fUUbid8aTNZiyjy2crcDx8aorpwTe9vjoQ+podICY= 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=Rh67uUSF; arc=none smtp.client-ip=209.85.128.182 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="Rh67uUSF" Received: by mail-yw1-f182.google.com with SMTP id 00721157ae682-78356c816fdso60085937b3.3 for ; Tue, 28 Oct 2025 03:57:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1761649055; x=1762253855; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=JKta5OIG3kDaKtHvMDVs9SJXcGqlkjKl/2SGt4edO/g=; b=Rh67uUSF6yUOSRAsHSRc/6i0MBwxfYRAEWJM51yln+IKQ6DuMXTzhLRhWMT2KPqRnG BSYbPUXmaic30e/UkPAN/YnF0nN6dWFZchnBhuhUuU+6g4D1M3kL8SUkWvJSmNgg3Xb7 Xn4dMpqg36FrjcmHeTMsXYEI9mgagSEQFsjS0gND02E9cELq9Ner6HMox0sTCJ6rl/nA jsYjqIWyhDlhkkV09s5UIG1UskkEIDyQTpVos/f3RRCzqOuwOSFv+6/IrYs/OeyO75Ql jc5xKy+ZxMhH7ZRIh74X/LbX35AjMYEKOsqECxFoLgZML0feou2GyDfxNe0TDM/PjoX+ 7M8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761649055; x=1762253855; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=JKta5OIG3kDaKtHvMDVs9SJXcGqlkjKl/2SGt4edO/g=; b=fodYaYztH88wdGkNjd2I23gsRfSvCsR1bCRNu2UBSzQj668B3lkLw5fmuA86bxtyc3 KuOFkuqFN7uMH/7d0V6bgzvqtUFOVxVQybINc+Ei4e1qnatRzzLYexGHd8zDbKVYKx90 Yf3j+xlW0ji8pUYwJgtNSs2hYuDi0zqT2c4kV8X1vaze5ZTgDkD8nk/ymA1QoEFERplx vkq4me7PibUlMuoQShJ+V5LfC44XG+k3lKY6fCJ0zobBwOSaJiRRhfPLD7kMwxFJnoew 8X8HfgS2K/fkvE/3iRN9LI7yP2szjb1a1MVCneFWp2uY9ZGUojAMkxHdAHd4rQIK+IgQ r6TA== X-Forwarded-Encrypted: i=1; AJvYcCVh2D8GEGqzJineM408d+DB4QDsfOldYgUg3oLryEJYpJC2BSiaKW7ze7dD30qXPGwnC86Pn7FAHncKpIg=@vger.kernel.org X-Gm-Message-State: AOJu0YxcgBbcKVN0IbydMAHyhqg0MizgX4zIx9QTnYwmhONxku6SJn1G smlgHUkX6bgT0RH4h2Xw6hrNRYioQDR0TpuapiVMDoYH8twRIVsjV2f5 X-Gm-Gg: ASbGncuLbpU7PbUMYPONpMVpAVAQivikk0e7e9jXZEWUPRWqtjn3/fJQmYNWeKZ/JUH uM/F9URCAyLiXMZRVsjKBnRCHIOyzHC98z5BUCtiBAJHdk2o8WDT/KZqxnOwT1GAm+Eh/LgCeyI Tc193l2Sa6UG+m5Tn6KuLXCy655D4ipE96ginXZyDFRXVeTcjyz28N2woqHpbKIR/mxIp0VUg+e U79PBYS7Fr+swQouDyRINrUmoS9NKeikix6rZR2Gz7kJqVt2VWMopup1QAPVDvZ/41Pq+WnYecQ f3K6AOaB4sl9SaXr+VKaYt+gRvBDqGCLkJLyB/TMKqp5+gw1+cu/CV+O0wgHTXxmjnIBA3d260E tZKFBUFQnsf7kAxPPta3BkjY2TseVs36jVbPW8i2iMKVD70twhzyrGUBZ8ZD+vOrN7ZoSKwLqL2 YMsfpL8rz/ X-Google-Smtp-Source: AGHT+IGQvUSHbn6/MJOvJ8swj31M4eBdE1W+SDgBok+Y6BScwqg28GcVuucyOJcpszsAmA8W5cbT7w== X-Received: by 2002:a05:690e:160a:b0:63e:28ae:97a8 with SMTP id 956f58d0204a3-63f6ba5fe3dmr2173155d50.45.1761649053935; Tue, 28 Oct 2025 03:57:33 -0700 (PDT) Received: from localhost ([2a03:2880:25ff:1::]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-63f4c45491fsm3107939d50.23.2025.10.28.03.57.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Oct 2025 03:57:33 -0700 (PDT) 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 v2 1/2] x86/boot: Fix page table access in 5-level to 4-level paging transition Date: Tue, 28 Oct 2025 10:55:56 +0000 Message-ID: <20251028105637.769470-2-usamaarif642@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251028105637.769470-1-usamaarif642@gmail.com> References: <20251028105637.769470-1-usamaarif642@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When transitioning from 5-level to 4-level paging, the existing code incorrectly accesses page table entries by directly dereferencing CR3 and applying PAGE_MASK. This approach has several issues: - __native_read_cr3() returns the raw CR3 register value, which on x86_64 includes not just the physical address but also flags. Bits above the physical address width of the system i.e. above __PHYSICAL_MASK_SHIFT) are also not masked. - The PGD entry is masked by PAGE_SIZE which doesn't take into account the higher bits such as _PAGE_BIT_NOPTISHADOW. Replace this with proper accessor functions: - native_read_cr3_pa(): Uses CR3_ADDR_MASK properly clearing SME encryption bit and extracting only the physical address portion. - mask pgd value with PTE_PFN_MASK instead of PAGE_MASK, accounting for flags above physical address (_PAGE_BIT_NOPTISHADOW in particular). Fixes: e9d0e6330eb8 ("x86/boot/compressed/64: Prepare new top-level page ta= ble for trampoline") 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 Acked-by: Dave Hansen Reviewed-by: Ard Biesheuvel --- arch/x86/boot/compressed/pgtable_64.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compress= ed/pgtable_64.c index bdd26050dff77..f812b81a538c2 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -3,6 +3,7 @@ #include #include #include +#include #include #include "../string.h" #include "efi.h" @@ -168,9 +169,10 @@ asmlinkage void configure_5level_paging(struct boot_pa= rams *bp, void *pgtable) * For 4- to 5-level paging transition, set up current CR3 as * the first and the only entry in a new top-level page table. */ - *trampoline_32bit =3D __native_read_cr3() | _PAGE_TABLE_NOENC; + *trampoline_32bit =3D native_read_cr3_pa() | _PAGE_TABLE_NOENC; } else { - unsigned long src; + u64 *new_cr3; + pgd_t *pgdp; =20 /* * For 5- to 4-level paging transition, copy page table pointed @@ -180,8 +182,9 @@ asmlinkage void configure_5level_paging(struct boot_par= ams *bp, void *pgtable) * We cannot just point to the page table from trampoline as it * may be above 4G. */ - src =3D *(unsigned long *)__native_read_cr3() & PAGE_MASK; - memcpy(trampoline_32bit, (void *)src, PAGE_SIZE); + pgdp =3D (pgd_t *)native_read_cr3_pa(); + new_cr3 =3D (u64 *)(pgd_val(pgdp[0]) & PTE_PFN_MASK); + memcpy(trampoline_32bit, new_cr3, PAGE_SIZE); } =20 toggle_la57(trampoline_32bit); --=20 2.47.3 From nobody Sun Feb 8 05:29:09 2026 Received: from mail-yx1-f53.google.com (mail-yx1-f53.google.com [74.125.224.53]) (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 D77D530648C for ; Tue, 28 Oct 2025 10:57:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.224.53 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761649058; cv=none; b=ah/oWQ8th4/QJFxbH2AdvKBDdRIkjuUIwH0GMlpSBytRz4xtylTMa3qpE4nNI6KcBHmOpZZbO7XPcfqKmsDK0J8sYSoO+INU4ZfkbmcbpU9C8CIAPC4Hl0a651E5XlNLHwmTUf/tmDOyifs5DtdHVZm0MiF2YY8KAK7nZkxqOiI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761649058; c=relaxed/simple; bh=1KqnUup5Uvt5Yo1XNIDIiQ1bv9k1F2hZl1gBY/MMm2U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LvZkeLgaOvZ/ztwZlDB19DEW/yzBMVIf9ok0jg566pJLtNed9egP+TgJOJv7t3vrgHlslcxH0q7tMn/iU5bNY31LmfGeLzsm2a0hvqE4khQlwFFEzVyV5v35Gs/gQVY1eVSXaE6r+yiHPwjEFqmGItCvqyhigNbuJXHzMs/P10Q= 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=k1pl2zV3; arc=none smtp.client-ip=74.125.224.53 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="k1pl2zV3" Received: by mail-yx1-f53.google.com with SMTP id 956f58d0204a3-63e2c7a3d10so6341184d50.2 for ; Tue, 28 Oct 2025 03:57:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1761649056; x=1762253856; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ZJ35wOcr7F7ww0bBd5XJ/JWerNufHMcq0vPwHXh1FHM=; b=k1pl2zV3LSQuVho0xVx+i4kjdKZbGuCGRJmv4Y3a8fp/vz8lHa6f7hPpOsHxWb+MlU 078Cy17C7nZ/v5B1RlcWT42uVYOAToz3hAPOGPJBnSCmRozXb0vbvWiMyNp+MathsW2t hJ2cw2Xp7wqXqRB7s/Sdzeep+8J+ZfZZ+GDLGnLNxPm1HoTMzPOZLnnqpQyXnnexLa5k FsGexJV313+rYAJxOWlazQPI4k9aqTjIgVF2U/B/GYRPfMdUiIsy/oEblR9VPBmbErbC wAYesK1AW2rWQ9OZVH3FtBDbJHNT93sfX8Kd+cK+VlbKlK1DP6Y8cD98FO+15kjakrPu tD5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761649056; x=1762253856; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ZJ35wOcr7F7ww0bBd5XJ/JWerNufHMcq0vPwHXh1FHM=; b=YWhNEL6qj8w588SqUKsQwdc3xJjb4GtvhTghzqX11vau7Gtd82VI4k8iSNvNwOsUHZ S8ddvvr5V9B+METUEI0sKFLDLierpYWb1x2F2GJKRgeBzqY0IoJ+vZ7rffQcuGWdANyX MX2tHfQqIM8cFxfb0l+/Alq3HIXUgqelYQh5j0GVe0Z2a/PDl//m0XVZhQWGd6a+H8up 6IvviDm3t3U8IT3ktbcy0/hfO3BUcDertYSFgLi6Cdsgl754kHHT7/+V/CF/404O8Jg2 OyUQbr8nAG6SG+Rjj7RxLRAdKGkBarNjtxBCYICmWXE0MYx7Ysav35e/VZoWycP2l0fA IhzA== X-Forwarded-Encrypted: i=1; AJvYcCUfK8gxLcqh8IUDxF93v3XpNSurMjqgJKZ3szNG37BFprhg7BmHg2gNTk4iqxRFgF5qahTIv5KrxLx0yQA=@vger.kernel.org X-Gm-Message-State: AOJu0YwBZP7VtM3Qk2dKkf6perXnna9OKR947QOLyQPJYut55HDVLEPb VvSaRJXpgwWoi2gTSb7vTwIqPe/O+WB1oBPiRyBHc7H9GvxvIVDV/vDa X-Gm-Gg: ASbGncsvmL+QzGdzFKXRtCW4ayPnsizW69tfRtPMVVCgnlkpnQDiyFtAytti9kSXbG/ 2/39/tGfWGQkHnECt2DEMArf7Ue1WZv8KnyivsUbiOWgZUUm9bCKKPSIVpczEltOCiRVlRSZZ3m MAtz2RCWCBwidnNrOT+FFPbPA04yE44+PrPmrKiSmw5NbvfM70beyRDTfk9V8Paz6SuNk3Xf46x 4V7UbMPYUN0HSF5B+3V3mhDn/XzyYe9gak1wNeQRO1l1cT/zvhb2Guo64/6El/YuoUx5KSL5S5C 6WEvXVfDLUz6SvxKx7tqTyAFLIOzOZYJDeqBUANb/BdXoLi+ufnvva0BIJ06dAbYVXOZfsLmwx1 bI/vNej2IAIHqepgBPx9nKJQoikVL9xH2QB4m6iN9faLYYbP5O+LzEsqHCvsMJUwNCPrG+Hr0fR 2goANTQME4 X-Google-Smtp-Source: AGHT+IE5U5L7FKFd11F0WQt1XNgBpiVo/IPo5RbWpv/iMvxvj22k5V3U3KCHcVeLyLEWrxgu6b4b4w== X-Received: by 2002:a05:690e:1503:b0:63e:1ee2:eb03 with SMTP id 956f58d0204a3-63f6ba8a0e8mr2831102d50.45.1761649055428; Tue, 28 Oct 2025 03:57:35 -0700 (PDT) Received: from localhost ([2a03:2880:25ff:6::]) by smtp.gmail.com with ESMTPSA id 00721157ae682-785ed1dde2bsm26598297b3.52.2025.10.28.03.57.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Oct 2025 03:57:34 -0700 (PDT) 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 v2 2/2] efi/libstub: Fix page table access in 5-level to 4-level paging transition Date: Tue, 28 Oct 2025 10:55:57 +0000 Message-ID: <20251028105637.769470-3-usamaarif642@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251028105637.769470-1-usamaarif642@gmail.com> References: <20251028105637.769470-1-usamaarif642@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When transitioning from 5-level to 4-level paging, the existing code incorrectly accesses page table entries by directly dereferencing CR3 and applying PAGE_MASK. This approach has several issues: - __native_read_cr3() returns the raw CR3 register value, which on x86_64 includes not just the physical address but also flags Bits above the physical address width of the system (i.e. above __PHYSICAL_MASK_SHIFT) are also not masked. - The pgd value is masked by PAGE_SIZE which doesn't take into account the higher bits such as _PAGE_BIT_NOPTISHADOW. Replace this with proper accessor functions: - native_read_cr3_pa(): Uses CR3_ADDR_MASK properly clearing SME encryption bit and extracting only the physical address portion. - mask pgd value with PTE_PFN_MASK instead of PAGE_MASK, accounting for flags above physical address (_PAGE_BIT_NOPTISHADOW in particular). Fixes: cb1c9e02b0c1 ("x86/efistub: Perform 4/5 level paging switch from the= stub") 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 Reviewed-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/x86-5lvl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/firmware/efi/libstub/x86-5lvl.c b/drivers/firmware/efi= /libstub/x86-5lvl.c index f1c5fb45d5f7c..36b4a611f6adf 100644 --- a/drivers/firmware/efi/libstub/x86-5lvl.c +++ b/drivers/firmware/efi/libstub/x86-5lvl.c @@ -66,7 +66,7 @@ void efi_5level_switch(void) bool have_la57 =3D native_read_cr4() & X86_CR4_LA57; bool need_toggle =3D want_la57 ^ have_la57; u64 *pgt =3D (void *)la57_toggle + PAGE_SIZE; - u64 *cr3 =3D (u64 *)__native_read_cr3(); + pgd_t *cr3 =3D (pgd_t *)native_read_cr3_pa(); u64 *new_cr3; =20 if (!la57_toggle || !need_toggle) @@ -82,7 +82,7 @@ void efi_5level_switch(void) new_cr3[0] =3D (u64)cr3 | _PAGE_TABLE_NOENC; } else { /* take the new root table pointer from the current entry #0 */ - new_cr3 =3D (u64 *)(cr3[0] & PAGE_MASK); + new_cr3 =3D (u64 *)(pgd_val(cr3[0]) & PTE_PFN_MASK); =20 /* copy the new root table if it is not 32-bit addressable */ if ((u64)new_cr3 > U32_MAX) --=20 2.47.3