Provide pmap_large_map() KPI on amd64.

The KPI allows to map very large contigous physical memory regions
into KVA, which are not covered by DMAP.

I see both with QEMU and with some real hardware started shipping, the
regions for NVDIMMs might be very far apart from the normal RAM, and
we expect that at least initial users of NVDIMM could install very
large amount of such memory.  IMO it is not reasonable to extend DMAP
to cover that far-away regions both because it could overflow existing
4T window for DMAP in KVA, and because it costs in page table pages
allocations, for gap and for possibly unused NV RAM.

Also, KPI provides some special functionality for fast cache flushing
based on the knowledge of the NVRAM mapping use.

Reviewed by:	alc, markj
Sponsored by:	The FreeBSD Foundation
Approved by:	re (gjb)
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D17070

2 files changed, 15 insertions, 1 deletions

diff --git a/sys/amd64/include/pmap.h b/sys/amd64/include/pmap.h
index 5b83307bbb68..2e0840ede15c 100644
--- a/sys/amd64/include/pmap.h
+++ b/sys/amd64/include/pmap.h
@@ -216,6 +216,10 @@
 #define	KPML4I		(NPML4EPG-1)
 #define	KPDPI		(NPDPEPG-2)	/* kernbase at -2GB */
 
+/* Large map: index of the first and max last pml4 entry */
+#define	LMSPML4I	(PML4PML4I + 1)
+#define	LMEPML4I	(DMPML4I - 1)
+
 /*
  * XXX doesn't really belong here I guess...
  */
@@ -413,11 +417,16 @@ void	pmap_bootstrap(vm_paddr_t *);
 int	pmap_cache_bits(pmap_t pmap, int mode, boolean_t is_pde);
 int	pmap_change_attr(vm_offset_t, vm_size_t, int);
 void	pmap_demote_DMAP(vm_paddr_t base, vm_size_t len, boolean_t invalidate);
+void	pmap_flush_cache_range(vm_offset_t, vm_offset_t);
+void	pmap_flush_cache_phys_range(vm_paddr_t, vm_paddr_t, vm_memattr_t);
 void	pmap_init_pat(void);
 void	pmap_kenter(vm_offset_t va, vm_paddr_t pa);
 void	*pmap_kenter_temporary(vm_paddr_t pa, int i);
 vm_paddr_t pmap_kextract(vm_offset_t);
 void	pmap_kremove(vm_offset_t);
+int	pmap_large_map(vm_paddr_t, vm_size_t, void **, vm_memattr_t);
+void	pmap_large_map_wb(void *sva, vm_size_t len);
+void	pmap_large_unmap(void *sva, vm_size_t len);
 void	*pmap_mapbios(vm_paddr_t, vm_size_t);
 void	*pmap_mapdev(vm_paddr_t, vm_size_t);
 void	*pmap_mapdev_attr(vm_paddr_t, vm_size_t, int);
diff --git a/sys/amd64/include/vmparam.h b/sys/amd64/include/vmparam.h
index 136e235cde45..22f75c1bf272 100644
--- a/sys/amd64/include/vmparam.h
+++ b/sys/amd64/include/vmparam.h
@@ -156,7 +156,9 @@
  * 0x0000000000000000 - 0x00007fffffffffff   user map
  * 0x0000800000000000 - 0xffff7fffffffffff   does not exist (hole)
  * 0xffff800000000000 - 0xffff804020100fff   recursive page table (512GB slot)
- * 0xffff804020101000 - 0xfffff7ffffffffff   unused
+ * 0xffff804020100fff - 0xffff807fffffffff   unused
+ * 0xffff808000000000 - 0xffff847fffffffff   large map (can be tuned up)
+ * 0xffff848000000000 - 0xfffff7ffffffffff   unused (large map extends there)
  * 0xfffff80000000000 - 0xfffffbffffffffff   4TB direct map
  * 0xfffffc0000000000 - 0xfffffdffffffffff   unused
  * 0xfffffe0000000000 - 0xffffffffffffffff   2TB kernel map
@@ -173,6 +175,9 @@
 #define	DMAP_MIN_ADDRESS	KVADDR(DMPML4I, 0, 0, 0)
 #define	DMAP_MAX_ADDRESS	KVADDR(DMPML4I + NDMPML4E, 0, 0, 0)
 
+#define	LARGEMAP_MIN_ADDRESS	KVADDR(LMSPML4I, 0, 0, 0)
+#define	LARGEMAP_MAX_ADDRESS	KVADDR(LMEPML4I + 1, 0, 0, 0)
+
 #define	KERNBASE		KVADDR(KPML4I, KPDPI, 0, 0)
 
 #define	UPT_MAX_ADDRESS		KVADDR(PML4PML4I, PML4PML4I, PML4PML4I, PML4PML4I)