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From: Greg Kroah-Hartman <>
To: Tom Lendacky <>
Cc:, Ard Biesheuvel <>
Subject: Re: [PATCH] x86/sme: Explicitly map new EFI memmap table as encrypted
Date: Sun, 12 Dec 2021 14:20:24 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Sat, Dec 11, 2021 at 11:19:00AM -0600, Tom Lendacky wrote:
> commit 1ff2fc02862d52e18fd3daabcfe840ec27e920a8 upstream
> to be applied to 4.14, 4.19 and 5.4.
> Reserving memory using efi_mem_reserve() calls into the x86
> efi_arch_mem_reserve() function. This function will insert a new EFI
> memory descriptor into the EFI memory map representing the area of
> memory to be reserved and marking it as EFI runtime memory. As part
> of adding this new entry, a new EFI memory map is allocated and mapped.
> The mapping is where a problem can occur. This new memory map is mapped
> using early_memremap() and generally mapped encrypted, unless the new
> memory for the mapping happens to come from an area of memory that is
> marked as EFI_BOOT_SERVICES_DATA memory. In this case, the new memory will
> be mapped unencrypted. However, during replacement of the old memory map,
> efi_mem_type() is disabled, so the new memory map will now be long-term
> mapped encrypted (in efi.memmap), resulting in the map containing invalid
> data and causing the kernel boot to crash.
> Since it is known that the area will be mapped encrypted going forward,
> explicitly map the new memory map as encrypted using early_memremap_prot().
> Cc: <> # 4.14.x
> Fixes: 8f716c9b5feb ("x86/mm: Add support to access boot related data in the clear")
> Link:
> Signed-off-by: Tom Lendacky <>
> [ardb: incorporate Kconfig fix by Arnd]
> Signed-off-by: Ard Biesheuvel <>
> ---
>  arch/x86/Kconfig               | 1 +
>  arch/x86/platform/efi/quirks.c | 3 ++-
>  2 files changed, 3 insertions(+), 1 deletion(-)

Now queued up, thanks.

greg k-h

  reply	other threads:[~2021-12-12 13:20 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-11 17:19 [PATCH] x86/sme: Explicitly map new EFI memmap table as encrypted Tom Lendacky
2021-12-12 13:20 ` Greg Kroah-Hartman [this message]
2021-12-14  9:09 ` Greg Kroah-Hartman
2021-12-14 11:54   ` Tom Lendacky
2021-12-14 13:40     ` Greg Kroah-Hartman
  -- strict thread matches above, loose matches on Subject: below --
2021-10-20 18:02 Tom Lendacky
2021-10-21 13:21 ` Tom Lendacky
2021-10-22 14:48   ` Ard Biesheuvel
2021-10-22 16:21     ` Tom Lendacky

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