litmus-rt-ext-res.git - LITMUS^RT with extended reservations for Forbidden Zones paper @ RTAS'20

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author	Thomas Lendacky <Thomas.Lendacky@amd.com>	2019-01-31 09:33:06 -0500
committer	Borislav Petkov <bp@suse.de>	2019-01-31 10:54:32 -0500
commit	912139cfbfa6a2bc1da052314d2c29338dae1f6a (patch)
tree	2e93dac323201a95d386f0886f2ba58541d980f8 /scripts/gdb/linux/proc.py
parent	0b053bbf07867c9942d706e70040398df59de54b (diff)

x86/microcode/amd: Don't falsely trick the late loading mechanism

The load_microcode_amd() function searches for microcode patches and attempts to apply a microcode patch if it is of different level than the currently installed level. While the processor won't actually load a level that is less than what is already installed, the logic wrongly returns UCODE_NEW thus signaling to its caller reload_store() that a late loading should be attempted. If the file-system contains an older microcode revision than what is currently running, such a late microcode reload can result in these misleading messages: x86/CPU: CPU features have changed after loading microcode, but might not take effect. x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update. These messages were issued on a system where SME/SEV are not enabled by the BIOS (MSR C001_0010[23] = 0b) because during boot, early_detect_mem_encrypt() is called and cleared the SME and SEV features in this case. However, after the wrong late load attempt, get_cpu_cap() is called and reloads the SME and SEV feature bits, resulting in the messages. Update the microcode level check to not attempt microcode loading if the current level is greater than(!) and not only equal to the current patch level. [ bp: massage commit message. ] Fixes: 2613f36ed965 ("x86/microcode: Attempt late loading only when new microcode is present") Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/154894518427.9406.8246222496874202773.stgit@tlendack-t1.amdoffice.net

Diffstat (limited to 'scripts/gdb/linux/proc.py')

0 files changed, 0 insertions, 0 deletions

/* * runtime-wrappers.c - Runtime Services function call wrappers * * Implementation summary: * ----------------------- * 1. When user/kernel thread requests to execute efi_runtime_service(), * enqueue work to efi_rts_wq. * 2. Caller thread waits for completion until the work is finished * because it's dependent on the return status and execution of * efi_runtime_service(). * For instance, get_variable() and get_next_variable(). * * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org> * * Split off from arch/x86/platform/efi/efi.c * * Copyright (C) 1999 VA Linux Systems * Copyright (C) 1999 Walt Drummond <drummond@valinux.com> * Copyright (C) 1999-2002 Hewlett-Packard Co. * Copyright (C) 2005-2008 Intel Co. * Copyright (C) 2013 SuSE Labs * * This file is released under the GPLv2. */ #define pr_fmt(fmt) "efi: " fmt #include <linux/bug.h> #include <linux/efi.h> #include <linux/irqflags.h> #include <linux/mutex.h> #include <linux/semaphore.h> #include <linux/stringify.h> #include <linux/workqueue.h> #include <linux/completion.h> #include <asm/efi.h> /* * Wrap around the new efi_call_virt_generic() macros so that the * code doesn't get too cluttered: */ #define efi_call_virt(f, args...) \ efi_call_virt_pointer(efi.systab->runtime, f, args) #define __efi_call_virt(f, args...) \ __efi_call_virt_pointer(efi.systab->runtime, f, args) struct efi_runtime_work efi_rts_work; /* * efi_queue_work: Queue efi_runtime_service() and wait until it's done * @rts: efi_runtime_service() function identifier * @rts_arg<1-5>: efi_runtime_service() function arguments * * Accesses to efi_runtime_services() are serialized by a binary * semaphore (efi_runtime_lock) and caller waits until the work is * finished, hence _only_ one work is queued at a time and the caller * thread waits for completion. */ #define efi_queue_work(_rts, _arg1, _arg2, _arg3, _arg4, _arg5) \ ({ \ efi_rts_work.status = EFI_ABORTED; \ \ if (!efi_enabled(EFI_RUNTIME_SERVICES)) { \ pr_warn_once("EFI Runtime Services are disabled!\n"); \ goto exit; \ } \ \ init_completion(&efi_rts_work.efi_rts_comp); \ INIT_WORK(&efi_rts_work.work, efi_call_rts); \ efi_rts_work.arg1 = _arg1; \ efi_rts_work.arg2 = _arg2; \ efi_rts_work.arg3 = _arg3; \ efi_rts_work.arg4 = _arg4; \ efi_rts_work.arg5 = _arg5; \ efi_rts_work.efi_rts_id = _rts; \ \ /* \ * queue_work() returns 0 if work was already on queue, \ * _ideally_ this should never happen. \ */ \ if (queue_work(efi_rts_wq, &efi_rts_work.work)) \ wait_for_completion(&efi_rts_work.efi_rts_comp); \ else \ pr_err("Failed to queue work to efi_rts_wq.\n"); \ \ exit: \ efi_rts_work.efi_rts_id = NONE; \ efi_rts_work.status; \ }) void efi_call_virt_check_flags(unsigned long flags, const char *call) { unsigned long cur_flags, mismatch; local_save_flags(cur_flags); mismatch = flags ^ cur_flags; if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK)) return; add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE); pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n", flags, cur_flags, call); local_irq_restore(flags); } /* * According to section 7.1 of the UEFI spec, Runtime Services are not fully * reentrant, and there are particular combinations of calls that need to be * serialized. (source: UEFI Specification v2.4A) * * Table 31. Rules for Reentry Into Runtime Services * +------------------------------------+-------------------------------+


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