[RFC v2 4/5] x86/crash: make the page that stores the LUKS volume key inaccessible

[Dave Hansen]

On 11/4/22 04:29, Coiby Xu wrote:
> +	if (kexec_crash_image->luks_volume_key_addr) {
> +		start = kexec_crash_image->luks_volume_key_addr;
> +		end = start + kexec_crash_image->luks_volume_key_sz - 1;
> +		page = pfn_to_page(start >> PAGE_SHIFT);
> +		nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
> +		set_memory_np((unsigned long)page_address(page), nr_pages);
> +	}

Why does this go pfn -> page -> vaddr?  What good does having the page
do?  Can you just do phys_to_virt() on the start address?  Maybe:

 	start_paddr = kexec_crash_image->luks_volume_key_addr;
 	end_paddr   = start_paddr + kexec_crash_image->luks_volume_key_sz - 1;
 	nr_pages = (PAGE_ALIGN(end_paddr) - PAGE_ALIGN_DOWN(start_paddr))/
PAGE_SIZE;
 	set_memory_np((unsigned long)phys_to_virt(start_paddr), nr_pages);

Also, if you resend this, please just cc the x86 folks on the series.
The other patches and cover letter have desperately needed context
around this.