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

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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: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo 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
This commit is contained in:
Ard Biesheuvel 2025-05-04 11:52:31 +02:00 committed by Ingo Molnar
parent 39ffd86dd7
commit bd4a58beaa
3 changed files with 14 additions and 14 deletions
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15
arch/x86/boot/startup/gdt_idt.c
View File

@ -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.
*/

1
arch/x86/include/asm/setup.h
View File

@ -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);

12
arch/x86/kernel/head64.c
View File

@ -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);
}