linux-kernel - [PATCH AUTOSEL 5.15 14/26] x86/boot: Move EFI range reservation after cmdline parsing

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Message-Id: <20211227190327.1042326-14-sashal@kernel.org>
Date:   Mon, 27 Dec 2021 14:03:15 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mike Rapoport <rppt@...nel.org>, Borislav Petkov <bp@...e.de>,
        Sasha Levin <sashal@...nel.org>, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, akpm@...ux-foundation.org,
        rafael.j.wysocki@...el.com, peterz@...radead.org,
        andriy.shevchenko@...ux.intel.com, jgross@...e.com
Subject: [PATCH AUTOSEL 5.15 14/26] x86/boot: Move EFI range reservation after cmdline parsing

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

[ Upstream commit 2f5b3514c33fecad4003ce0f22ca9691492d310b ]

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.

See also https://lore.kernel.org/r/e8dd8993c38702ee6dd73b3c11f158617e665607.camel@intel.com

  [ bp: Turn 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/20211213112757.2612-4-bp@alien8.de
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 40ed44ead0631..48596f9fddf45 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
-- 
2.34.1