[PATCH] i386: PARAVIRT: add kmap_atomic_pte for mapping highpte pages
Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space. These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.
Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.
This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings. Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.
[ Zach - vmi.c will need some attention after this patch. It wasn't
immediately obvious to me what needs to be done. ]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 645d440..bca8e2d 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -27,6 +27,8 @@
unsigned int nr_free_highpages(void);
extern unsigned long totalhigh_pages;
+void kmap_flush_unused(void);
+
#else /* CONFIG_HIGHMEM */
static inline unsigned int nr_free_highpages(void) { return 0; }
@@ -44,9 +46,13 @@
#define kmap_atomic(page, idx) \
({ pagefault_disable(); page_address(page); })
+#define kmap_atomic_prot(page, idx, prot) kmap_atomic(page, idx)
+
#define kunmap_atomic(addr, idx) do { pagefault_enable(); } while (0)
#define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx))
#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
+
+#define kmap_flush_unused() do {} while(0)
#endif
#endif /* CONFIG_HIGHMEM */