Re: [PATCH v7 3/9] x86/startup_64: Simplify calculation of initial page table address

[Borislav Petkov]

On Tue, Feb 27, 2024 at 04:19:11PM +0100, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@xxxxxxxxxx>
> 
> Determining the address of the initial page table to program into CR3
> involves:
> - taking the physical address
> - adding the SME encryption mask
> 
> On the primary entry path, the code is mapped using a 1:1 virtual to
> physical translation, so the physical address can be taken directly
> using a RIP-relative LEA instruction.
> 
> On the secondary entry path, the address can be obtained by taking the
> offset from the virtual kernel base (__START_kernel_map) and adding the
> physical kernel base.
> 
> This is implemented in a slightly confusing way, so clean this up.
> 
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> ---
>  arch/x86/kernel/head_64.S | 25 ++++++--------------
>  1 file changed, 7 insertions(+), 18 deletions(-)

Reviewed-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>

-- 
Regards/Gruss,
    Boris.

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