From nobody Sun Feb 8 12:36:32 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 722FCC4332F for ; Thu, 8 Dec 2022 19:04:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229995AbiLHTEA (ORCPT ); Thu, 8 Dec 2022 14:04:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229781AbiLHTDx (ORCPT ); Thu, 8 Dec 2022 14:03:53 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56E7A8DFF3; Thu, 8 Dec 2022 11:03:52 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id B43B4CE2682; Thu, 8 Dec 2022 19:03:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FF5CC433EF; Thu, 8 Dec 2022 19:03:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670526228; bh=nOb1rqG+d8zAEK4Zjd64IrjJmxoyMzvK3YWdEydV4hE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TjOuOAxixZBCl04IjpGO52FgDvhWH4b8bah7zDSb5uxlbSrHT804XFcsokQR/GnW1 8dwlbyq5TZj9EHDAl5LvJyQJAz/UaZflGUDInWSJxcPnby73b/R1BjbK/hJfT6hsEQ dLo1PngRDgnqgK+wNLIGjTQyt2Yqg2DUwGJPyfuDphY8JoJsfsphcyCvc10SYRmayn DLlLZ3zVJ2+b/EbBl0RSsQDJETBxE4t6totU/D/55Y5+PfzHMkJ7pWblSAUPpCmyHS qgtW72xKSVvfi+r/REtBsSbog33B5Yl0lWhssgOTxymiooLCHieA0kfEiCtTNtL8bk T0x0eGq0mi3Xg== From: Bjorn Helgaas To: linux-pci@vger.kernel.org Cc: Hans de Goede , Florent DELAHAYE , Konrad J Hambrick , Matt Hansen <2lprbe78@duck.com>, =?UTF-8?q?Benoit=20Gr=C3=A9goire?= , Nicholas Johnson , Mika Westerberg , Werner Sembach , mumblingdrunkard@protonmail.com, linux-kernel@vger.kernel.org, Bjorn Helgaas Subject: [PATCH v2 1/4] efi/x86: Remove EfiMemoryMappedIO from E820 map Date: Thu, 8 Dec 2022 13:03:38 -0600 Message-Id: <20221208190341.1560157-2-helgaas@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221208190341.1560157-1-helgaas@kernel.org> References: <20221208190341.1560157-1-helgaas@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Bjorn Helgaas Firmware can use EfiMemoryMappedIO to request that MMIO regions be mapped by the OS so they can be accessed by EFI runtime services, but should have no other significance to the OS (UEFI r2.10, sec 7.2). However, most bootloaders and EFI stubs convert EfiMemoryMappedIO regions to E820_TYPE_RESERVED entries, which prevent Linux from allocating space from them (see remove_e820_regions()). Some platforms use EfiMemoryMappedIO entries for PCI MMCONFIG space and PCI host bridge windows, which means Linux can't allocate BAR space for hot-added devices. Remove large EfiMemoryMappedIO regions from the E820 map to avoid this problem. Leave small (< 256KB) EfiMemoryMappedIO regions alone because on some platforms, these describe non-window space that's included in host bridge _CRS. If we assign that space to PCI devices, they don't work. On the Lenovo X1 Carbon, this leads to suspend/resume failures. The previous solution to the problem of allocating BARs in these regions was to add pci_crs_quirks[] entries to disable E820 checking for these machines (see d341838d776a ("x86/PCI: Disable E820 reserved region clipping via quirks")): Acer DMI_PRODUCT_NAME Spin SP513-54N Clevo DMI_BOARD_NAME X170KM-G Lenovo DMI_PRODUCT_VERSION *IIL* Florent reported the BAR allocation issue on the Clevo NL4XLU. We could add another quirk for the NL4XLU, but I hope this generic change can solve it for many machines without having to add quirks. This change has been tested on Clevo X170KM-G (Konrad) and Lenovo Ideapad Slim 3 (Matt) and solves the problem even when overriding the existing quirks by booting with "pci=3Duse_e820". Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D216565 Clevo NL4XLU Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D206459#c78 Clevo X170KM= -G Link: https://bugzilla.redhat.com/show_bug.cgi?id=3D1868899 Ideapad Slim= 3 Link: https://bugzilla.redhat.com/show_bug.cgi?id=3D2029207 X1 Carbon Reported-by: Florent DELAHAYE Tested-by: Konrad J Hambrick Tested-by: Matt Hansen <2lprbe78@duck.com> Signed-off-by: Bjorn Helgaas Cc: Hans de Goede --- arch/x86/platform/efi/efi.c | 46 +++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index ebc98a68c400..dee1852e95cd 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -303,6 +303,50 @@ static void __init efi_clean_memmap(void) } } =20 +/* + * Firmware can use EfiMemoryMappedIO to request that MMIO regions be + * mapped by the OS so they can be accessed by EFI runtime services, but + * should have no other significance to the OS (UEFI r2.10, sec 7.2). + * However, most bootloaders and EFI stubs convert EfiMemoryMappedIO + * regions to E820_TYPE_RESERVED entries, which prevent Linux from + * allocating space from them (see remove_e820_regions()). + * + * Some platforms use EfiMemoryMappedIO entries for PCI MMCONFIG space and + * PCI host bridge windows, which means Linux can't allocate BAR space for + * hot-added devices. + * + * Remove large EfiMemoryMappedIO regions from the E820 map to avoid this + * problem. + * + * Retain small EfiMemoryMappedIO regions because on some platforms, these + * describe non-window space that's included in host bridge _CRS. If we + * assign that space to PCI devices, they don't work. + */ +static void __init efi_remove_e820_mmio(void) +{ + efi_memory_desc_t *md; + u64 size, start, end; + int i =3D 0; + + for_each_efi_memory_desc(md) { + if (md->type =3D=3D EFI_MEMORY_MAPPED_IO) { + size =3D md->num_pages << EFI_PAGE_SHIFT; + if (size >=3D 256*1024) { + start =3D md->phys_addr; + end =3D start + size - 1; + pr_info("Remove mem%02u: MMIO range=3D[0x%08llx-0x%08llx] (%lluMB) fro= m e820 map\n", + i, start, end, size >> 20); + e820__range_remove(start, size, + E820_TYPE_RESERVED, 1); + } else { + pr_info("Not removing mem%02u: MMIO range=3D[0x%08llx-0x%08llx] (%lluK= B) from e820 map\n", + i, start, end, size >> 10); + } + } + i++; + } +} + void __init efi_print_memmap(void) { efi_memory_desc_t *md; @@ -474,6 +518,8 @@ void __init efi_init(void) set_bit(EFI_RUNTIME_SERVICES, &efi.flags); efi_clean_memmap(); =20 + efi_remove_e820_mmio(); + if (efi_enabled(EFI_DBG)) efi_print_memmap(); } --=20 2.25.1