Re: [PATCH v3 3/4] x86/mm: Flush global TLB when switching to trampoline page-table

[Borislav Petkov]

On Fri, Oct 01, 2021 at 05:48:16PM +0200, Joerg Roedel wrote:
> diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
> index 31b5856010cb..b9802b18f504 100644
> --- a/arch/x86/realmode/init.c
> +++ b/arch/x86/realmode/init.c
> @@ -17,6 +17,29 @@ u32 *trampoline_cr4_features;
>  /* Hold the pgd entry used on booting additional CPUs */
>  pgd_t trampoline_pgd_entry;
>  
> +void load_trampoline_pgtable(void)
> +{
> +#ifdef CONFIG_X86_32
> +	load_cr3(initial_page_table);
> +#else
> +	/* Exiting long mode will fail if CR4.PCIDE is set. */

So this comment is not valid anymore if this is a separate function - it
is valid only when that function is called in reboot.c so I guess you
should leave that comment there.

> +	if (boot_cpu_has(X86_FEATURE_PCID))
> +		cr4_clear_bits(X86_CR4_PCIDE);
> +
> +	write_cr3(real_mode_header->trampoline_pgd);

Is there any significance to the reordering of those calls here? The
commit message doesn't say...

-- 
Regards/Gruss,
    Boris.

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