linux-kernel - Re: [PATCH v7 1/3] efi/x86: Fix EFI memory map corruption with kexec

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Message-ID: <20240603144639.GCZl3XTwmFHwi-KUZW@fat_crate.local>
Date: Mon, 3 Jun 2024 16:46:39 +0200
From: Borislav Petkov <bp@...en8.de>
To: "Kalra, Ashish" <ashish.kalra@....com>
Cc: Mike Rapoport <rppt@...nel.org>, tglx@...utronix.de, mingo@...hat.com,
	dave.hansen@...ux.intel.com, x86@...nel.org, rafael@...nel.org,
	hpa@...or.com, peterz@...radead.org, adrian.hunter@...el.com,
	sathyanarayanan.kuppuswamy@...ux.intel.com, jun.nakajima@...el.com,
	rick.p.edgecombe@...el.com, thomas.lendacky@....com,
	michael.roth@....com, seanjc@...gle.com, kai.huang@...el.com,
	bhe@...hat.com, kirill.shutemov@...ux.intel.com, bdas@...hat.com,
	vkuznets@...hat.com, dionnaglaze@...gle.com, anisinha@...hat.com,
	jroedel@...e.de, ardb@...nel.org, kexec@...ts.infradead.org,
	linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/3] efi/x86: Fix EFI memory map corruption with kexec

On Mon, Jun 03, 2024 at 09:01:49AM -0500, Kalra, Ashish wrote:
> If we skip efi_arch_mem_reserve() (which should probably be anyway skipped
> for kexec case), then for kexec boot, EFI memmap is memremapped in the same
> virtual address as the first kernel and not the allocated memblock address.

Are you saying that we should simply do

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index fdf07dd6f459..410cb0743289 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -577,6 +577,9 @@ void __init efi_mem_reserve(phys_addr_t addr, u64 size)
 	if (WARN_ON_ONCE(efi_enabled(EFI_PARAVIRT)))
 		return;
 
+	if (kexec_in_progress)
+		return;
+
 	if (!memblock_is_region_reserved(addr, size))
 		memblock_reserve(addr, size);
 
and skip that whole call?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette