Messages in this thread Patch in this message | | | From | NOMURA JUNICHI(野村 淳一) <> | Subject | [PATCH] x86/boot: Add a message about ignored early NMIs | Date | Thu, 11 Jan 2024 12:18:58 +0000 |
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Commit 78a509fba9c9 ("x86/boot: Ignore NMIs during very early boot") added empty handler in early boot stage to avoid boot failure by spurious NMIs.
Add a diagnostic message in case we need to know whether early NMIs have occurred and/or what happened to them.
Signed-off-by: Jun'ichi Nomura <junichi.nomura@nec.com> Suggested-by: Borislav Petkov <bp@alien8.de> Suggested-by: H. Peter Anvin <hpa@zytor.com> Link: https://lore.kernel.org/lkml/20231130103339.GCZWhlA196uRklTMNF@fat_crate.local/
diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c --- a/arch/x86/boot/compressed/ident_map_64.c +++ b/arch/x86/boot/compressed/ident_map_64.c @@ -387,7 +387,10 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code) kernel_add_identity_map(address, end); }
+extern int spurious_nmi_count; + void do_boot_nmi_trap(struct pt_regs *regs, unsigned long error_code) { /* Empty handler to ignore NMI during early boot */ + spurious_nmi_count++; } diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -357,6 +357,8 @@ unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr, return entry; }
+int spurious_nmi_count; + /* * The compressed kernel image (ZO), has been moved so that its position * is against the end of the buffer used to hold the uncompressed kernel @@ -493,6 +495,12 @@ 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 NMI ignored. Number of NMIs: 0x"); + error_puthex(spurious_nmi_count); + error_putstr("\n"); + } + return output + entry_offset; }
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