FAILED: Patch "x86/kexec: Copy ACPI root pointer address from config table" failed to apply to 6.1-stable tree

FAILED: Patch "x86/kexec: Copy ACPI root pointer address from config table" failed to apply to 6.1-stable tree

[Sasha Levin]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From e00ac9e5afb5d80c0168ec88d8e8662a54af8249 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Tue, 17 Feb 2026 12:09:35 +0100
Subject: [PATCH] x86/kexec: Copy ACPI root pointer address from config table

Dave reports that kexec may fail when the first kernel boots via the EFI
stub but without EFI runtime services, as in that case, the RSDP address
field in struct bootparams is never assigned. Kexec copies this value
into the version of struct bootparams that it provides to the incoming
kernel, which may have no other means to locate the ACPI root pointer.

So take the value from the EFI config tables if no root pointer has been
set in the first kernel's struct bootparams.

Fixes: a1b87d54f4e4 ("x86/efistub: Avoid legacy decompressor when doing EFI boot")
Cc: <stable@vger.kernel.org> # v6.1
Reported-by: Dave Young <dyoung@redhat.com>
Tested-by: Dave Young <dyoung@redhat.com>
Link: https://lore.kernel.org/linux-efi/aZQg_tRQmdKNadCg@darkstar.users.ipa.redhat.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/kernel/kexec-bzimage64.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 7508d0ccc7403..251edc5a040fc 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -193,6 +193,13 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
 	struct efi_info *current_ei = &boot_params.efi_info;
 	struct efi_info *ei = &params->efi_info;
 
+	if (!params->acpi_rsdp_addr) {
+		if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
+			params->acpi_rsdp_addr = efi.acpi20;
+		else if (efi.acpi != EFI_INVALID_TABLE_ADDR)
+			params->acpi_rsdp_addr = efi.acpi;
+	}
+
 	if (!efi_enabled(EFI_RUNTIME_SERVICES))
 		return 0;
 
-- 
2.51.0