Commit bd4a58be authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Ingo Molnar
Browse files

x86/boot: Move early_setup_gdt() back into head64.c 



Move early_setup_gdt() out of the startup code that is callable from the
1:1 mapping - this is not needed, and instead, it is better to expose
the helper that does reside in __head directly.

This reduces the amount of code that needs special checks for 1:1
execution suitability. In particular, it avoids dealing with the GHCB
page (and its physical address) in startup code, which runs from the
1:1 mapping, making physical to virtual translations ambiguous.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Loughlin <kevinloughlin@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-efi@vger.kernel.org
Link: https://lore.kernel.org/r/20250504095230.2932860-26-ardb+git@google.com
parent 39ffd86d

arch/x86/boot/startup/gdt_idt.c

+1 −14
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ 
static gate_desc bringup_idt_table[NUM_EXCEPTION_VECTORS] __page_aligned_data;



/* This may run while still in the direct mapping */

static void __head startup_64_load_idt(void *vc_handler)

void __head startup_64_load_idt(void *vc_handler)

{

	struct desc_ptr desc = {

		.address = (unsigned long)rip_rel_ptr(bringup_idt_table),
@@ -43,19 +43,6 @@ static void __head startup_64_load_idt(void *vc_handler) 
	native_load_idt(&desc);

}



/* This is used when running on kernel addresses */

void early_setup_idt(void)

{

	void *handler = NULL;



	if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {

		setup_ghcb();

		handler = vc_boot_ghcb;

	}



	startup_64_load_idt(handler);

}



/*

 * Setup boot CPU state needed before kernel switches to virtual addresses.

 */

arch/x86/include/asm/setup.h

+1 −0
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ extern void reserve_standard_io_resources(void); 
extern void i386_reserve_resources(void);

extern unsigned long __startup_64(unsigned long p2v_offset, struct boot_params *bp);

extern void startup_64_setup_gdt_idt(void);

extern void startup_64_load_idt(void *vc_handler);

extern void early_setup_idt(void);

extern void __init do_early_exception(struct pt_regs *regs, int trapnr);

arch/x86/kernel/head64.c

+12 −0
Original line number Diff line number Diff line
@@ -303,3 +303,15 @@ void __init __noreturn x86_64_start_reservations(char *real_mode_data) 


	start_kernel();

}



void early_setup_idt(void)

{

	void *handler = NULL;



	if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {

		setup_ghcb();

		handler = vc_boot_ghcb;

	}



	startup_64_load_idt(handler);

}