Re: [RFC PATCH v1 10/18] x86/efi: Access EFI related tables in the clear

On Thu, 09 Jun, at 11:16:40AM, Tom Lendacky wrote:

So maybe something along the lines of an enum that would have entries
(initially) like KERNEL_DATA (equal to zero) and EFI_DATA. Others could
be added later as needed.

 
Sure, that works for me, though maybe BOOT_DATA would be more
applicable considering the devicetree case too.

Would you then want to allow the protection attributes to be updated
by architecture specific code through something like a __weak function?
In the x86 case I can add this function as a non-SME specific function
that would initially just have the SME-related mask modification in it.

Would we need a new function? Couldn't we just have a new
FIXMAP_PAGE_* constant? e.g. would something like this work?

---

enum memremap_owner {
	KERNEL_DATA = 0,
	BOOT_DATA,
};

void __init *
early_memremap(resource_size_t phys_addr, unsigned long size,
	       enum memremap_owner owner)
{
	pgprot_t prot;

	switch (owner) {
	case BOOT_DATA:
		prot = FIXMAP_PAGE_BOOT;
		break;
	case KERNEL_DATA:	/* FALLTHROUGH */
	default:
		prot = FIXMAP_PAGE_NORMAL;
		
	}

	return (__force void *)__early_ioremap(phys_addr, size, prot);
}

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