Re: [RFC Part1 PATCH v3 15/17] x86: Add support for changing memory encryption attribute in early boot

[Brijesh Singh <brijesh.singh@amd.com>]

Hi Boris,


On 8/28/17 5:51 AM, Borislav Petkov wrote:

[..]

> +static int __init early_set_memory_enc_dec(resource_size_t paddr,
>> +					   unsigned long size, bool enc)
>> +{
>> +	unsigned long vaddr, vaddr_end, vaddr_next;
>> +	unsigned long psize, pmask;
>> +	int split_page_size_mask;
>> +	pte_t *kpte;
>> +	int level;
>> +
>> +	vaddr = (unsigned long)__va(paddr);
>> +	vaddr_next = vaddr;
>> +	vaddr_end = vaddr + size;
>> +
>> +	/*
>> +	 * We are going to change the physical page attribute from C=1 to C=0
>> +	 * or vice versa. Flush the caches to ensure that data is written into
>> +	 * memory with correct C-bit before we change attribute.
>> +	 */
>> +	clflush_cache_range(__va(paddr), size);
>> +
>> +	for (; vaddr < vaddr_end; vaddr = vaddr_next) {
>> +		kpte = lookup_address(vaddr, &level);
>> +		if (!kpte || pte_none(*kpte))
>> +			return 1;
> Return before flushing TLBs? Perhaps you mean
>
> 			ret = 1;
> 			goto out;
>
> here and out does
>
> 	__flush_tlb_all();
> 	return ret;

thanks, good catch. I will fix in next rev.

-Brijesh