ad8d74559b
[ Upstream commit 78a509fba9c9b1fcb77f95b7c6be30da3d24823a ] When there are two racing NMIs on x86, the first NMI invokes NMI handler and the 2nd NMI is latched until IRET is executed. If panic on NMI and panic kexec are enabled, the first NMI triggers panic and starts booting the next kernel via kexec. Note that the 2nd NMI is still latched. During the early boot of the next kernel, once an IRET is executed as a result of a page fault, then the 2nd NMI is unlatched and invokes the NMI handler. However, NMI handler is not set up at the early stage of boot, which results in a boot failure. Avoid such problems by setting up a NOP handler for early NMIs. [ mingo: Refined the changelog. ] Signed-off-by: Jun'ichi Nomura <junichi.nomura@nec.com> Signed-off-by: Derek Barbosa <debarbos@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
55 lines
1.3 KiB
C
Executable file
55 lines
1.3 KiB
C
Executable file
// SPDX-License-Identifier: GPL-2.0-only
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#include <asm/trap_pf.h>
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#include <asm/segment.h>
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#include <asm/trapnr.h>
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#include "misc.h"
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static void set_idt_entry(int vector, void (*handler)(void))
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{
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unsigned long address = (unsigned long)handler;
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gate_desc entry;
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memset(&entry, 0, sizeof(entry));
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entry.offset_low = (u16)(address & 0xffff);
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entry.segment = __KERNEL_CS;
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entry.bits.type = GATE_TRAP;
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entry.bits.p = 1;
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entry.offset_middle = (u16)((address >> 16) & 0xffff);
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entry.offset_high = (u32)(address >> 32);
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memcpy(&boot_idt[vector], &entry, sizeof(entry));
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}
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/* Have this here so we don't need to include <asm/desc.h> */
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static void load_boot_idt(const struct desc_ptr *dtr)
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{
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asm volatile("lidt %0"::"m" (*dtr));
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}
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/* Setup IDT before kernel jumping to .Lrelocated */
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void load_stage1_idt(void)
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{
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boot_idt_desc.address = (unsigned long)boot_idt;
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if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT))
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set_idt_entry(X86_TRAP_VC, boot_stage1_vc);
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load_boot_idt(&boot_idt_desc);
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}
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/* Setup IDT after kernel jumping to .Lrelocated */
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void load_stage2_idt(void)
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{
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boot_idt_desc.address = (unsigned long)boot_idt;
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set_idt_entry(X86_TRAP_PF, boot_page_fault);
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set_idt_entry(X86_TRAP_NMI, boot_nmi_trap);
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#ifdef CONFIG_AMD_MEM_ENCRYPT
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set_idt_entry(X86_TRAP_VC, boot_stage2_vc);
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#endif
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load_boot_idt(&boot_idt_desc);
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}
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