linux-kernel - [PATCH 3/3] x86/boot: Move EFI range reservation after cmdline parsing

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Message-Id: <20211213112757.2612-4-bp@alien8.de>
Date:   Mon, 13 Dec 2021 12:27:57 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        Juergen Gross <jgross@...e.com>,
        John Dorminy <jdorminy@...hat.com>, anjaneya.chagam@...el.com,
        dan.j.williams@...el.com, Hugh Dickins <hughd@...gle.com>,
        "Patrick J. Volkerding" <volkerdi@...il.com>
Subject: [PATCH 3/3] x86/boot: Move EFI range reservation after cmdline parsing

From: Mike Rapoport <rppt@...nel.org>

The memory reservation in arch/x86/platform/efi/efi.c depends on at
least two command line parameters. Put it back later in the boot process
and move efi_memblock_x86_reserve_range() out of early_memory_reserve().

An attempt to fix this was done in

  8d48bf8206f7 ("x86/boot: Pull up cmdline preparation and early param parsing")

but that caused other troubles so it got reverted.

The bug this is addressing is:

Dan reports that Anjaneya Chagam can no longer use the efi=nosoftreserve
kernel command line parameter to suppress "soft reservation" behavior.

This is due to the fact that the following call-chain happens at boot:

early_reserve_memory
|-> efi_memblock_x86_reserve_range
    |-> efi_fake_memmap_early

which does

        if (!efi_soft_reserve_enabled())
                return;

and that would have set EFI_MEM_NO_SOFT_RESERVE after having parsed
"nosoftreserve".

However, parse_early_param() gets called *after* it, leading to the boot
cmdline not being taken into account.

 [ bp: Productize into a proper patch. ]

Signed-off-by: Mike Rapoport <rppt@...nel.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lore.kernel.org/r/e8dd8993c38702ee6dd73b3c11f158617e665607.camel@intel.com
---
 arch/x86/kernel/setup.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 49b596db5631..e04f5e6eb33f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -713,9 +713,6 @@ static void __init early_reserve_memory(void)
 
 	early_reserve_initrd();
 
-	if (efi_enabled(EFI_BOOT))
-		efi_memblock_x86_reserve_range();
-
 	memblock_x86_reserve_range_setup_data();
 
 	reserve_ibft_region();
@@ -890,6 +887,9 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
+	if (efi_enabled(EFI_BOOT))
+		efi_memblock_x86_reserve_range();
+
 #ifdef CONFIG_MEMORY_HOTPLUG
 	/*
 	 * Memory used by the kernel cannot be hot-removed because Linux
-- 
2.29.2