Re: [PATCH v5 1/7] mce: fix set_mce_nospec to always unmap the whole page

Jane Chu
2022-02-02T21:21:06Z

On 2/2/2022 5:21 AM, Christoph Hellwig wrote:
>> +static inline int set_mce_nospec(unsigned long pfn)
>> {
>> unsigned long decoy_addr;
>> int rc;
>> @@ -117,10 +113,7 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
>> */
>> decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63));
>>
>> - if (unmap)
>> - rc = set_memory_np(decoy_addr, 1);
>> - else
>> - rc = set_memory_uc(decoy_addr, 1);
>> + rc = set_memory_np(decoy_addr, 1);
>> if (rc)
>> pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn);
>> return rc;
>> @@ -130,7 +123,7 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
>> /* Restore full speculative operation to the pfn. */
>> static inline int clear_mce_nospec(unsigned long pfn)
>> {
>> - return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1);
>> + return _set_memory_present((unsigned long) pfn_to_kaddr(pfn), 1);
>> }
>
> Wouldn't it make more sense to move these helpers out of line rather
> than exporting _set_memory_present?

Do you mean to move
return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_PRESENT), 0);
into clear_mce_nospec() for the x86 arch and get rid of _set_memory_present?
If so, sure I'll do that.

>
>> /*
>> - * _set_memory_prot is an internal helper for callers that have been passed
>> + * __set_memory_prot is an internal helper for callers that have been passed
>
> This looks unrelated to the patch.

My bad, will remove the remnant.

thanks!
-jane