From 550b33cfd445296868a478e8413ffb2e963eed32 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 10 Nov 2022 10:36:20 +0100 Subject: arm64: efi: Force the use of SetVirtualAddressMap() on Altra machines Ampere Altra machines are reported to misbehave when the SetTime() EFI runtime service is called after ExitBootServices() but before calling SetVirtualAddressMap(). Given that the latter is horrid, pointless and explicitly documented as optional by the EFI spec, we no longer invoke it at boot if the configured size of the VA space guarantees that the EFI runtime memory regions can remain mapped 1:1 like they are at boot time. On Ampere Altra machines, this results in SetTime() calls issued by the rtc-efi driver triggering synchronous exceptions during boot. We can now recover from those without bringing down the system entirely, due to commit 23715a26c8d81291 ("arm64: efi: Recover from synchronous exceptions occurring in firmware"). However, it would be better to avoid the issue entirely, given that the firmware appears to remain in a funny state after this. So attempt to identify these machines based on the 'family' field in the type #1 SMBIOS record, and call SetVirtualAddressMap() unconditionally in that case. Tested-by: Alexandru Elisei Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/Makefile | 2 +- drivers/firmware/efi/libstub/arm64-stub.c | 17 ++++++++++- drivers/firmware/efi/libstub/efistub.h | 28 ++++++++++++++++++ drivers/firmware/efi/libstub/smbios.c | 48 +++++++++++++++++++++++++++++++ 4 files changed, 93 insertions(+), 2 deletions(-) create mode 100644 drivers/firmware/efi/libstub/smbios.c (limited to 'drivers') diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index b1601aad7e1a..ef5045a53ce0 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -82,7 +82,7 @@ $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o lib-$(CONFIG_ARM) += arm32-stub.o -lib-$(CONFIG_ARM64) += arm64-stub.o +lib-$(CONFIG_ARM64) += arm64-stub.o smbios.o lib-$(CONFIG_X86) += x86-stub.o lib-$(CONFIG_RISCV) += riscv-stub.o lib-$(CONFIG_LOONGARCH) += loongarch-stub.o diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 259e4b852d63..f9de5217ea65 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -15,6 +15,21 @@ #include "efistub.h" +static bool system_needs_vamap(void) +{ + const u8 *type1_family = efi_get_smbios_string(1, family); + + /* + * Ampere Altra machines crash in SetTime() if SetVirtualAddressMap() + * has not been called prior. + */ + if (!type1_family || strcmp(type1_family, "Altra")) + return false; + + efi_warn("Working around broken SetVirtualAddressMap()\n"); + return true; +} + efi_status_t check_platform_features(void) { u64 tg; @@ -24,7 +39,7 @@ efi_status_t check_platform_features(void) * UEFI runtime regions 1:1 and so calling SetVirtualAddressMap() is * unnecessary. */ - if (VA_BITS_MIN >= 48) + if (VA_BITS_MIN >= 48 && !system_needs_vamap()) efi_novamap = true; /* UEFI mandates support for 4 KB granularity, no need to check */ diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index a30fb5d8ef05..eb03d5a9aac8 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -975,4 +975,32 @@ efi_enable_reset_attack_mitigation(void) { } void efi_retrieve_tpm2_eventlog(void); +struct efi_smbios_record { + u8 type; + u8 length; + u16 handle; +}; + +struct efi_smbios_type1_record { + struct efi_smbios_record header; + + u8 manufacturer; + u8 product_name; + u8 version; + u8 serial_number; + efi_guid_t uuid; + u8 wakeup_type; + u8 sku_number; + u8 family; +}; + +#define efi_get_smbios_string(__type, __name) ({ \ + int size = sizeof(struct efi_smbios_type ## __type ## _record); \ + int off = offsetof(struct efi_smbios_type ## __type ## _record, \ + __name); \ + __efi_get_smbios_string(__type, off, size); \ +}) + +const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize); + #endif diff --git a/drivers/firmware/efi/libstub/smbios.c b/drivers/firmware/efi/libstub/smbios.c new file mode 100644 index 000000000000..460418b7f5f5 --- /dev/null +++ b/drivers/firmware/efi/libstub/smbios.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0-only +// Copyright 2022 Google LLC +// Author: Ard Biesheuvel + +#include + +#include "efistub.h" + +typedef struct efi_smbios_protocol efi_smbios_protocol_t; + +struct efi_smbios_protocol { + efi_status_t (__efiapi *add)(efi_smbios_protocol_t *, efi_handle_t, + u16 *, struct efi_smbios_record *); + efi_status_t (__efiapi *update_string)(efi_smbios_protocol_t *, u16 *, + unsigned long *, u8 *); + efi_status_t (__efiapi *remove)(efi_smbios_protocol_t *, u16); + efi_status_t (__efiapi *get_next)(efi_smbios_protocol_t *, u16 *, u8 *, + struct efi_smbios_record **, + efi_handle_t *); + + u8 major_version; + u8 minor_version; +}; + +const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize) +{ + struct efi_smbios_record *record; + efi_smbios_protocol_t *smbios; + efi_status_t status; + u16 handle = 0xfffe; + const u8 *strtable; + + status = efi_bs_call(locate_protocol, &EFI_SMBIOS_PROTOCOL_GUID, NULL, + (void **)&smbios) ?: + efi_call_proto(smbios, get_next, &handle, &type, &record, NULL); + if (status != EFI_SUCCESS) + return NULL; + + strtable = (u8 *)record + recsize; + for (int i = 1; i < ((u8 *)record)[offset]; i++) { + int len = strlen(strtable); + + if (!len) + return NULL; + strtable += len + 1; + } + return strtable; +} -- cgit v1.2.3