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

Jane Chu
2022-02-02T23:08:04Z

On 2/2/2022 1:20 PM, Jane Chu wrote:
> 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.

Looks like I can't do that. It's either exporting
_set_memory_present(), or exporting change_page_attr_set(). Perhaps the
former is more conventional?

-jane