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s390/mm: tag normal pages vs pages used in page tables

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The ESSA instruction has a new option that allows to tag pages that
are not used as a page table. Without the tag the hypervisor has to
assume that any guest page could be used in a page table inside the
guest. This forces the hypervisor to flush all guest TLB entries
whenever a host page table entry is invalidated. With the tag
the host can skip the TLB flush if the page is tagged as normal page.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2016-06-14 12:56:01 +02:00
parent 520eccdfe1
commit c9b5ad546e
8 changed files with 209 additions and 22 deletions
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2
arch/s390/mm/pgalloc.c
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@@ -57,6 +57,7 @@ unsigned long *crst_table_alloc(struct mm_struct *mm)
if (!page)
return NULL;
arch_set_page_dat(page, 2);
return (unsigned long *) page_to_phys(page);
}
@@ -214,6 +215,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
__free_page(page);
return NULL;
}
arch_set_page_dat(page, 0);
/* Initialize page table */
table = (unsigned long *) page_to_phys(page);
if (mm_alloc_pgste(mm)) {