From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4EA8314F9F8; Mon, 9 Dec 2024 17:02:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733763753; cv=none; b=tAMCC9xAw7krQUWWTdkFhPfaWcuNrX4M1a6AghhkHncL9Ya1nd1qo7+SLBrGXi6L8MqYgxLY1XnIeH8CkKh5cxkcu+HbLvscBGahG1/9llTwCbidt64MPWOOLYULO4qRbMpQNlyIn6Pwy0sdrFMt+ejJUZEcIE5lWkVBkKa83Ck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733763753; c=relaxed/simple; bh=TgECz1ImA/rmKbcmW5GPn4At4ClQAqIrMHIpuT+dGaI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ERpQf8dD6uGDAUGYvP308/meD6Kwe9NjnsaBmLKPSIyS1JcXnvQc93X2h7f+Db4whoqjtkVD2Lur9EBIxdimeRUMf52iedzh2oDuj7XhHBUbNSxThzOY26xCAAaJgBZs8WHTN8eHsHFWRNBz+zvaf5eblYSw9KlIapJgHLy04Jw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=JKoKI8Xk; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="JKoKI8Xk" Received: from [192.168.2.246] (unknown [70.49.166.4]) by linux.microsoft.com (Postfix) with ESMTPSA id 76CBF20ACD6A; Mon, 9 Dec 2024 09:02:24 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 76CBF20ACD6A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1733763745; bh=1BVACcjTRKyUgpLPUdy/K7pIzmBSCoBv7TYoN90iukg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=JKoKI8XkKzqZ/roYeTuGzSk9glgde3ri7vboDZbRFtqKy1un6mkxlsuU1STk8uiW1 axyqTaZgaBcgszLuuKH4W54jvSYh6UB4icrKmtXT0gIGNBcXfcDUsp9+ubCrgUuxpg 6HPAb9+A2nYqqe8fB1o0PyN6QCG5K76p/JfYa3PY= Message-ID: <380bbf4b-0828-444e-9b93-fa639cc23a1a@linux.microsoft.com> Date: Mon, 9 Dec 2024 12:02:13 -0500 Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] efi: make the min and max mmap slack slots configurable To: Ard Biesheuvel Cc: linux-efi@vger.kernel.org, stable@vger.kernel.org, Tyler Hicks , Brian Nguyen , Jacob Pan , Allen Pais , Jonathan Marek , Ilias Apalodimas , Kuppuswamy Sathyanarayanan , Jeremy Linton , "Kirill A. Shutemov" , =?UTF-8?B?S09ORE8gS0FaVU1BKOi/keiXpCDlkoznnJ8p?= , Kees Cook , "Borislav Petkov (AMD)" , Yuntao Wang , Aditya Garg , open list References: <20241209162449.48390-1-hamzamahfooz@linux.microsoft.com> Content-Language: en-US From: Hamza Mahfooz In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Ard, On 12/9/24 11:40, Ard Biesheuvel wrote: > Hello Hamza, > > Thanks for the patch. > > On Mon, 9 Dec 2024 at 17:25, Hamza Mahfooz > wrote: >> >> Recent platforms > > Which platforms are you referring to here? Grace Blackwell 200 in particular. > >> require more slack slots than the current value of >> EFI_MMAP_NR_SLACK_SLOTS, otherwise they fail to boot. So, introduce >> EFI_MIN_NR_MMAP_SLACK_SLOTS and EFI_MAX_NR_MMAP_SLACK_SLOTS >> and use them to determine a number of slots that the platform >> is willing to accept. >> > > What does 'acceptance' mean in this case? Not having allocate_pool() return EFI_BUFFER_TOO_SMALL. > >> Cc: stable@vger.kernel.org >> Cc: Tyler Hicks >> Tested-by: Brian Nguyen >> Tested-by: Jacob Pan >> Reviewed-by: Allen Pais > > I appreciate the effort of your colleagues, but if these > tested/reviewed-bys were not given on an open list, they are > meaningless, and I am going to drop them unless the people in question > reply to this thread. > >> Signed-off-by: Hamza Mahfooz >> --- >> drivers/firmware/efi/Kconfig | 23 +++++++++++++++++ >> .../firmware/efi/libstub/efi-stub-helper.c | 2 +- >> drivers/firmware/efi/libstub/efistub.h | 15 +---------- >> drivers/firmware/efi/libstub/kaslr.c | 2 +- >> drivers/firmware/efi/libstub/mem.c | 25 +++++++++++++++---- >> drivers/firmware/efi/libstub/randomalloc.c | 2 +- >> drivers/firmware/efi/libstub/relocate.c | 2 +- >> drivers/firmware/efi/libstub/x86-stub.c | 8 +++--- >> 8 files changed, 52 insertions(+), 27 deletions(-) >> > > This looks rather intrusive for a patch that is intended as cc:stable. > >> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig >> index e312d731f4a3..7fedc271d543 100644 >> --- a/drivers/firmware/efi/Kconfig >> +++ b/drivers/firmware/efi/Kconfig >> @@ -155,6 +155,29 @@ config EFI_TEST >> Say Y here to enable the runtime services support via /dev/efi_test. >> If unsure, say N. >> >> +# >> +# An efi_boot_memmap is used by efi_get_memory_map() to return the >> +# EFI memory map in a dynamically allocated buffer. >> +# >> +# The buffer allocated for the EFI memory map includes extra room for >> +# a range of [EFI_MIN_NR_MMAP_SLACK_SLOTS, EFI_MAX_NR_MMAP_SLACK_SLOTS] >> +# additional EFI memory descriptors. This facilitates the reuse of the >> +# EFI memory map buffer when a second call to ExitBootServices() is >> +# needed because of intervening changes to the EFI memory map. Other >> +# related structures, e.g. x86 e820ext, need to factor in this headroom >> +# requirement as well. >> +# >> + >> +config EFI_MIN_NR_MMAP_SLACK_SLOTS >> + int >> + depends on EFI >> + default 8 >> + >> +config EFI_MAX_NR_MMAP_SLACK_SLOTS >> + int >> + depends on EFI >> + default 64 >> + > > What would be the reason for not always bumping this to 64? I personally don't mind always bumping it up, but it seemed to me like it might regress existing platforms if we did that. > >> config EFI_DEV_PATH_PARSER >> bool >> >> diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c >> index c0c81ca4237e..adf2b0c0dd34 100644 >> --- a/drivers/firmware/efi/libstub/efi-stub-helper.c >> +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c >> @@ -432,7 +432,7 @@ efi_status_t efi_exit_boot_services(void *handle, void *priv, >> if (efi_disable_pci_dma) >> efi_pci_disable_bridge_busmaster(); >> >> - status = efi_get_memory_map(&map, true); >> + status = efi_get_memory_map(&map, true, NULL); >> if (status != EFI_SUCCESS) >> return status; >> >> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h >> index 76e44c185f29..d86c6e13de5f 100644 >> --- a/drivers/firmware/efi/libstub/efistub.h >> +++ b/drivers/firmware/efi/libstub/efistub.h >> @@ -160,19 +160,6 @@ void efi_set_u64_split(u64 data, u32 *lo, u32 *hi) >> */ >> #define EFI_100NSEC_PER_USEC ((u64)10) >> >> -/* >> - * An efi_boot_memmap is used by efi_get_memory_map() to return the >> - * EFI memory map in a dynamically allocated buffer. >> - * >> - * The buffer allocated for the EFI memory map includes extra room for >> - * a minimum of EFI_MMAP_NR_SLACK_SLOTS additional EFI memory descriptors. >> - * This facilitates the reuse of the EFI memory map buffer when a second >> - * call to ExitBootServices() is needed because of intervening changes to >> - * the EFI memory map. Other related structures, e.g. x86 e820ext, need >> - * to factor in this headroom requirement as well. >> - */ >> -#define EFI_MMAP_NR_SLACK_SLOTS 8 >> - >> typedef struct efi_generic_dev_path efi_device_path_protocol_t; >> >> union efi_device_path_to_text_protocol { >> @@ -1059,7 +1046,7 @@ void efi_apply_loadoptions_quirk(const void **load_options, u32 *load_options_si >> char *efi_convert_cmdline(efi_loaded_image_t *image); >> >> efi_status_t efi_get_memory_map(struct efi_boot_memmap **map, >> - bool install_cfg_tbl); >> + bool install_cfg_tbl, unsigned int *n); >> >> efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr, >> unsigned long max); >> diff --git a/drivers/firmware/efi/libstub/kaslr.c b/drivers/firmware/efi/libstub/kaslr.c >> index 6318c40bda38..06e7a1ef34ab 100644 >> --- a/drivers/firmware/efi/libstub/kaslr.c >> +++ b/drivers/firmware/efi/libstub/kaslr.c >> @@ -62,7 +62,7 @@ static bool check_image_region(u64 base, u64 size) >> bool ret = false; >> int map_offset; >> >> - status = efi_get_memory_map(&map, false); >> + status = efi_get_memory_map(&map, false, NULL); >> if (status != EFI_SUCCESS) >> return false; >> >> diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c >> index 4f1fa302234d..cab25183b790 100644 >> --- a/drivers/firmware/efi/libstub/mem.c >> +++ b/drivers/firmware/efi/libstub/mem.c >> @@ -13,32 +13,47 @@ >> * configuration table >> * >> * Retrieve the UEFI memory map. The allocated memory leaves room for >> - * up to EFI_MMAP_NR_SLACK_SLOTS additional memory map entries. >> + * up to CONFIG_EFI_MAX_NR_MMAP_SLACK_SLOTS additional memory map entries. >> * >> * Return: status code >> */ >> efi_status_t efi_get_memory_map(struct efi_boot_memmap **map, >> - bool install_cfg_tbl) >> + bool install_cfg_tbl, >> + unsigned int *n) > > What is the purpose of 'n'? Having single letter names for function > parameters is not great for legibility. > >> { >> int memtype = install_cfg_tbl ? EFI_ACPI_RECLAIM_MEMORY >> : EFI_LOADER_DATA; >> efi_guid_t tbl_guid = LINUX_EFI_BOOT_MEMMAP_GUID; >> + unsigned int nr = CONFIG_EFI_MIN_NR_MMAP_SLACK_SLOTS; >> struct efi_boot_memmap *m, tmp; >> efi_status_t status; >> unsigned long size; >> >> + BUILD_BUG_ON(!is_power_of_2(CONFIG_EFI_MIN_NR_MMAP_SLACK_SLOTS) || >> + !is_power_of_2(CONFIG_EFI_MAX_NR_MMAP_SLACK_SLOTS) || >> + CONFIG_EFI_MIN_NR_MMAP_SLACK_SLOTS >= >> + CONFIG_EFI_MAX_NR_MMAP_SLACK_SLOTS); >> + >> tmp.map_size = 0; >> status = efi_bs_call(get_memory_map, &tmp.map_size, NULL, &tmp.map_key, >> &tmp.desc_size, &tmp.desc_ver); >> if (status != EFI_BUFFER_TOO_SMALL) >> return EFI_LOAD_ERROR; >> >> - size = tmp.map_size + tmp.desc_size * EFI_MMAP_NR_SLACK_SLOTS; >> - status = efi_bs_call(allocate_pool, memtype, sizeof(*m) + size, >> - (void **)&m); >> + do { >> + size = tmp.map_size + tmp.desc_size * nr; >> + status = efi_bs_call(allocate_pool, memtype, sizeof(*m) + size, >> + (void **)&m); >> + nr <<= 1; >> + } while (status == EFI_BUFFER_TOO_SMALL && >> + nr <= CONFIG_EFI_MAX_NR_MMAP_SLACK_SLOTS); >> + > > Under what circumstances would you expect AllocatePool() to return > EFI_BUFFER_TOO_SMALL? What is the purpose of this loop? We have observed that allocate_pool() will return EFI_BUFFER_TOO_SMALL if EFI_MMAP_NR_SLACK_SLOTS is less than 32. The loop is there so only the minimum number of extra slots are allocated. > > How did you test this code? I was able to successfully boot the platform with this patch applied, without it we need to append `efi=disable_early_pci_dma` to the kernel's cmdline be able to boot the system. > >> if (status != EFI_SUCCESS) >> return status; >> >> + if (n) >> + *n = nr; >> + >> if (install_cfg_tbl) { >> /* >> * Installing a configuration table might allocate memory, and >> diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c >> index c41e7b2091cd..e80a65e7b87a 100644 >> --- a/drivers/firmware/efi/libstub/randomalloc.c >> +++ b/drivers/firmware/efi/libstub/randomalloc.c >> @@ -65,7 +65,7 @@ efi_status_t efi_random_alloc(unsigned long size, >> efi_status_t status; >> int map_offset; >> >> - status = efi_get_memory_map(&map, false); >> + status = efi_get_memory_map(&map, false, NULL); >> if (status != EFI_SUCCESS) >> return status; >> >> diff --git a/drivers/firmware/efi/libstub/relocate.c b/drivers/firmware/efi/libstub/relocate.c >> index d694bcfa1074..b7b0aad95ba4 100644 >> --- a/drivers/firmware/efi/libstub/relocate.c >> +++ b/drivers/firmware/efi/libstub/relocate.c >> @@ -28,7 +28,7 @@ efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align, >> unsigned long nr_pages; >> int i; >> >> - status = efi_get_memory_map(&map, false); >> + status = efi_get_memory_map(&map, false, NULL); >> if (status != EFI_SUCCESS) >> goto fail; >> >> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c >> index 188c8000d245..cb14f0d2a3d9 100644 >> --- a/drivers/firmware/efi/libstub/x86-stub.c >> +++ b/drivers/firmware/efi/libstub/x86-stub.c >> @@ -740,15 +740,15 @@ static efi_status_t allocate_e820(struct boot_params *params, >> struct efi_boot_memmap *map; >> efi_status_t status; >> __u32 nr_desc; >> + __u32 nr; >> >> - status = efi_get_memory_map(&map, false); >> + status = efi_get_memory_map(&map, false, &nr); >> if (status != EFI_SUCCESS) >> return status; >> >> nr_desc = map->map_size / map->desc_size; >> - if (nr_desc > ARRAY_SIZE(params->e820_table) - EFI_MMAP_NR_SLACK_SLOTS) { >> - u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table) + >> - EFI_MMAP_NR_SLACK_SLOTS; >> + if (nr_desc > ARRAY_SIZE(params->e820_table) - nr) { >> + u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table) + nr; >> >> status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size); >> } >> -- >> 2.47.1 >>