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x86/boot: Add a message about ignored early NMIs

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  78a509fba9 ("x86/boot: Ignore NMIs during very early boot")

added an empty handler in early boot stage to avoid boot failure due to
spurious NMIs.

Add a diagnostic message to show that early NMIs have occurred.

  [ bp: Touchups. ]

  [ Committer note: tested by stopping the guest really early and
    injecting NMIs through qemu's monitor. Result:

    early console in setup code
    Spurious early NMIs ignored: 13
    ... ]

Suggested-by: Borislav Petkov <bp@alien8.de>
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Jun'ichi Nomura <junichi.nomura@nec.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/lkml/20231130103339.GCZWhlA196uRklTMNF@fat_crate.local
This commit is contained in:
NOMURA JUNICHI(野村　淳一) 2024-02-02 03:51:58 +00:00 • committed by Borislav Petkov (AMD)
parent 9ba8ec8ee6
commit ac456ca0af
3 changed files with 9 additions and 1 deletions
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2
arch/x86/boot/compressed/ident_map_64.c
View file

@ -389,5 +389,5 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
void do_boot_nmi_trap(struct pt_regs *regs, unsigned long error_code)
{
/* Empty handler to ignore NMI during early boot */
spurious_nmi_count++;
}

7
arch/x86/boot/compressed/misc.c
View file

@ -52,6 +52,7 @@ struct port_io_ops pio_ops;
memptr free_mem_ptr;
memptr free_mem_end_ptr;
int spurious_nmi_count;
static char *vidmem;
static int vidport;
@ -506,6 +507,12 @@ asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
/* Disable exception handling before booting the kernel */
cleanup_exception_handling();
if (spurious_nmi_count) {
error_putstr("Spurious early NMIs ignored: ");
error_putdec(spurious_nmi_count);
error_putstr("\n");
}
return output + entry_offset;
}

1
arch/x86/boot/compressed/misc.h
View file

@ -59,6 +59,7 @@ extern char _head[], _end[];
/* misc.c */
extern memptr free_mem_ptr;
extern memptr free_mem_end_ptr;
extern int spurious_nmi_count;
void *malloc(int size);
void free(void *where);
void __putstr(const char *s);