[AMD Official Use Only - General]
Hello Boris,
>> It is basically an index into the 4K page within the hugepage mapped
>> in the RMP table or in other words an index into the RMP table entry
>> for 4K page(s) corresponding to a hugepage.
>So pte_index(address) and for 1G pages, pmd_index(address).
>So no reinventing the wheel if we already have helpers for that.
>Yes that makes sense and pte_index(address) is exactly what is required for 2M hugepages.
>Will use pte_index() for 2M pages and pmd_index() for 1G pages.
Had a relook into this.
As I mentioned earlier, this is computing an index into a 4K page within a hugepage mapping,
therefore, though pte_index() works for 2M pages, but pmd_index() will not work for 1G pages.
We basically need to do :
pfn |= (address >> PAGE_SHIFT) & mask;
where mask is the (number of 4K pages per hugepage) - 1
So this still needs the original code but with a fix for mask computation as following :
static inline size_t pages_per_hpage(int level)
return page_level_size(level) / PAGE_SIZE;
}
static int handle_user_rmp_page_fault(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
...
pfn = pte_pfn(*pte);
/* If its large page then calculte the fault pfn */
if (level > PG_LEVEL_4K) {
+ /*
+ * index into the 4K page within the hugepage mapping
+ * in the RMP table
+ */
unsigned long mask;
- mask = pages_per_hpage(level) - pages_per_hpage(level - 1);
+ mask = pages_per_hpage(level) - 1;
pfn |= (address >> PAGE_SHIFT) & mask;
Thanks,
Ashish
