Commit b099155e authored by Joerg Roedel's avatar Joerg Roedel Committed by Borislav Petkov
Browse files

x86/boot/compressed/64: Cleanup exception handling before booting kernel 



Disable the exception handling before booting the kernel to make sure
any exceptions that happen during early kernel boot are not directed to
the pre-decompression code.

Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210312123824.306-2-joro@8bytes.org
parent afb4a377

arch/x86/boot/compressed/idt_64.c

+14 −0
Original line number Diff line number Diff line
@@ -52,3 +52,17 @@ void load_stage2_idt(void) 


	load_boot_idt(&boot_idt_desc);

}



void cleanup_exception_handling(void)

{

	/*

	 * Flush GHCB from cache and map it encrypted again when running as

	 * SEV-ES guest.

	 */

	sev_es_shutdown_ghcb();



	/* Set a null-idt, disabling #PF and #VC handling */

	boot_idt_desc.size    = 0;

	boot_idt_desc.address = 0;

	load_boot_idt(&boot_idt_desc);

}

arch/x86/boot/compressed/misc.c

+2 −5
Original line number Diff line number Diff line
@@ -443,11 +443,8 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 
	handle_relocations(output, output_len, virt_addr);

	debug_putstr("done.\nBooting the kernel.\n");



	/*

	 * Flush GHCB from cache and map it encrypted again when running as

	 * SEV-ES guest.

	 */

	sev_es_shutdown_ghcb();

	/* Disable exception handling before booting the kernel */

	cleanup_exception_handling();



	return output;

}

arch/x86/boot/compressed/misc.h

+6 −0
Original line number Diff line number Diff line
@@ -155,6 +155,12 @@ extern pteval_t __default_kernel_pte_mask; 
extern gate_desc boot_idt[BOOT_IDT_ENTRIES];

extern struct desc_ptr boot_idt_desc;



#ifdef CONFIG_X86_64

void cleanup_exception_handling(void);

#else

static inline void cleanup_exception_handling(void) { }

#endif



/* IDT Entry Points */

void boot_page_fault(void);

void boot_stage1_vc(void);