linux-kernel - [PATCH v2 2/2] x86/efi: Apply EFI Memory Attributes after kexec

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Message-ID: <20241112185217.48792-2-nsaenz@amazon.com>
Date: Tue, 12 Nov 2024 18:52:17 +0000
From: Nicolas Saenz Julienne <nsaenz@...zon.com>
To: Ard Biesheuvel <ardb@...nel.org>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>, Matt Fleming
	<matt@...eblueprint.co.uk>, <linux-efi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <stanspas@...zon.de>,
	<nh-open-source@...zon.com>, Nicolas Saenz Julienne <nsaenz@...zon.com>,
	<stable@...r.kernel.org>
Subject: [PATCH v2 2/2] x86/efi: Apply EFI Memory Attributes after kexec

Kexec bypasses EFI's switch to virtual mode. In exchange, it has its own
routine, kexec_enter_virtual_mode(), which replays the mappings made by
the original kernel. Unfortunately, that function fails to reinstate
EFI's memory attributes, which would've otherwise been set after
entering virtual mode. Remediate this by calling
efi_runtime_update_mappings() within kexec's routine.

Cc: stable@...r.kernel.org
Fixes: 18141e89a76c ("x86/efi: Add support for EFI_MEMORY_ATTRIBUTES_TABLE")
Signed-off-by: Nicolas Saenz Julienne <nsaenz@...zon.com>

---

Notes:
- Tested with QEMU/OVMF.

 arch/x86/platform/efi/efi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 375ebd78296a..a7ff189421c3 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -765,6 +765,7 @@ static void __init kexec_enter_virtual_mode(void)
 
 	efi_sync_low_kernel_mappings();
 	efi_native_runtime_setup();
+	efi_runtime_update_mappings();
 #endif
 }
 
-- 
2.40.1