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Date:      Sat, 3 Aug 2019 01:36:06 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r350551 - in head/sys: amd64/amd64 i386/i386 i386/include
Message-ID:  <201908030136.x731a6Qu096237@repo.freebsd.org>

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Author: jhb
Date: Sat Aug  3 01:36:05 2019
New Revision: 350551
URL: https://svnweb.freebsd.org/changeset/base/350551

Log:
  Don't reset memory attributes when mapping physical addresses for ACPI.
  
  Previously, AcpiOsMemory was using pmap_mapbios which would always map
  the requested address Write-Back (WB).  For several AMD Ryzen laptops,
  the BIOS uses AcpiOsMemory to directly access the PCI MCFG region in
  order to access PCI config registers.  This has the side effect of
  remapping the MCFG region in the direct map as WB instead of UC
  hanging the laptops during boot.
  
  On the one laptop I examined in detail, the _PIC global method used to
  switch from 8259A PICs to I/O APICs uses a pair of PCI config space
  registers at offset 0x84 in the device at 0:0:0 to as a pair of
  address/data registers to access an indirect register in the chipset
  and clear a single bit to switch modes.
  
  To fix, alter the semantics of pmap_mapbios() such that it does not
  modify the attributes of any existing mappings and instead uses the
  existing attributes.  If a new mapping is created, this new mapping
  uses WB (the default memory attribute).
  
  Special thanks to the gentleman whose name I don't have who brought
  two affected laptops to the hacker lounge at BSDCan.  Direct access to
  the affected systems permitted finding the root cause within an hour
  or so.
  
  PR:		231760, 236899
  Reviewed by:	kib, alc
  MFC after:	2 weeks
  Differential Revision:	https://reviews.freebsd.org/D20327

Modified:
  head/sys/amd64/amd64/pmap.c
  head/sys/i386/i386/pmap.c
  head/sys/i386/i386/pmap_base.c
  head/sys/i386/include/pmap_base.h

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Sat Aug  3 01:06:17 2019	(r350550)
+++ head/sys/amd64/amd64/pmap.c	Sat Aug  3 01:36:05 2019	(r350551)
@@ -1097,6 +1097,13 @@ static caddr_t crashdumpmap;
 #define	PMAP_ENTER_NORECLAIM	0x1000000	/* Don't reclaim PV entries. */
 #define	PMAP_ENTER_NOREPLACE	0x2000000	/* Don't replace mappings. */
 
+/*
+ * Internal flags for pmap_mapdev_internal() and
+ * pmap_change_attr_locked().
+ */
+#define	MAPDEV_FLUSHCACHE	0x0000001	/* Flush cache after mapping. */
+#define	MAPDEV_SETATTR		0x0000002	/* Modify existing attrs. */
+
 static void	free_pv_chunk(struct pv_chunk *pc);
 static void	free_pv_entry(pmap_t pmap, pv_entry_t pv);
 static pv_entry_t get_pv_entry(pmap_t pmap, struct rwlock **lockp);
@@ -1117,7 +1124,7 @@ static pv_entry_t pmap_pvh_remove(struct md_page *pvh,
 		    vm_offset_t va);
 
 static int pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode,
-    bool noflush);
+    int flags);
 static boolean_t pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va);
 static boolean_t pmap_demote_pde_locked(pmap_t pmap, pd_entry_t *pde,
     vm_offset_t va, struct rwlock **lockp);
@@ -7711,7 +7718,7 @@ pmap_pde_attr(pd_entry_t *pde, int cache_bits, int mas
  * NOT real memory.
  */
 static void *
-pmap_mapdev_internal(vm_paddr_t pa, vm_size_t size, int mode, bool noflush)
+pmap_mapdev_internal(vm_paddr_t pa, vm_size_t size, int mode, int flags)
 {
 	struct pmap_preinit_mapping *ppim;
 	vm_offset_t va, offset;
@@ -7745,7 +7752,8 @@ pmap_mapdev_internal(vm_paddr_t pa, vm_size_t size, in
 		for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
 			ppim = pmap_preinit_mapping + i;
 			if (ppim->pa == pa && ppim->sz == size &&
-			    ppim->mode == mode)
+			    (ppim->mode == mode ||
+			    (flags & MAPDEV_SETATTR) == 0))
 				return ((void *)(ppim->va + offset));
 		}
 		/*
@@ -7754,9 +7762,12 @@ pmap_mapdev_internal(vm_paddr_t pa, vm_size_t size, in
 		 */
 		if (pa < dmaplimit && pa + size <= dmaplimit) {
 			va = PHYS_TO_DMAP(pa);
-			PMAP_LOCK(kernel_pmap);
-			i = pmap_change_attr_locked(va, size, mode, noflush);
-			PMAP_UNLOCK(kernel_pmap);
+			if ((flags & MAPDEV_SETATTR) != 0) {
+				PMAP_LOCK(kernel_pmap);
+				i = pmap_change_attr_locked(va, size, mode, flags);
+				PMAP_UNLOCK(kernel_pmap);
+			} else
+				i = 0;
 			if (!i)
 				return ((void *)(va + offset));
 		}
@@ -7767,7 +7778,7 @@ pmap_mapdev_internal(vm_paddr_t pa, vm_size_t size, in
 	for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE)
 		pmap_kenter_attr(va + tmpsize, pa + tmpsize, mode);
 	pmap_invalidate_range(kernel_pmap, va, va + tmpsize);
-	if (!noflush)
+	if ((flags & MAPDEV_FLUSHCACHE) != 0)
 		pmap_invalidate_cache_range(va, va + tmpsize);
 	return ((void *)(va + offset));
 }
@@ -7776,28 +7787,31 @@ void *
 pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
 {
 
-	return (pmap_mapdev_internal(pa, size, mode, false));
+	return (pmap_mapdev_internal(pa, size, mode, MAPDEV_FLUSHCACHE |
+	    MAPDEV_SETATTR));
 }
 
 void *
 pmap_mapdev(vm_paddr_t pa, vm_size_t size)
 {
 
-	return (pmap_mapdev_internal(pa, size, PAT_UNCACHEABLE, false));
+	return (pmap_mapdev_attr(pa, size, PAT_UNCACHEABLE));
 }
 
 void *
 pmap_mapdev_pciecfg(vm_paddr_t pa, vm_size_t size)
 {
 
-	return (pmap_mapdev_internal(pa, size, PAT_UNCACHEABLE, true));
+	return (pmap_mapdev_internal(pa, size, PAT_UNCACHEABLE,
+	    MAPDEV_SETATTR));
 }
 
 void *
 pmap_mapbios(vm_paddr_t pa, vm_size_t size)
 {
 
-	return (pmap_mapdev_internal(pa, size, PAT_WRITE_BACK, false));
+	return (pmap_mapdev_internal(pa, size, PAT_WRITE_BACK,
+	    MAPDEV_FLUSHCACHE));
 }
 
 void
@@ -7936,13 +7950,13 @@ pmap_change_attr(vm_offset_t va, vm_size_t size, int m
 	int error;
 
 	PMAP_LOCK(kernel_pmap);
-	error = pmap_change_attr_locked(va, size, mode, false);
+	error = pmap_change_attr_locked(va, size, mode, MAPDEV_FLUSHCACHE);
 	PMAP_UNLOCK(kernel_pmap);
 	return (error);
 }
 
 static int
-pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode, bool noflush)
+pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode, int flags)
 {
 	vm_offset_t base, offset, tmpva;
 	vm_paddr_t pa_start, pa_end, pa_end1;
@@ -8059,7 +8073,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size
 					/* Run ended, update direct map. */
 					error = pmap_change_attr_locked(
 					    PHYS_TO_DMAP(pa_start),
-					    pa_end - pa_start, mode, noflush);
+					    pa_end - pa_start, mode, flags);
 					if (error != 0)
 						break;
 					/* Start physical address run. */
@@ -8089,7 +8103,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size
 					/* Run ended, update direct map. */
 					error = pmap_change_attr_locked(
 					    PHYS_TO_DMAP(pa_start),
-					    pa_end - pa_start, mode, noflush);
+					    pa_end - pa_start, mode, flags);
 					if (error != 0)
 						break;
 					/* Start physical address run. */
@@ -8117,7 +8131,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size
 					/* Run ended, update direct map. */
 					error = pmap_change_attr_locked(
 					    PHYS_TO_DMAP(pa_start),
-					    pa_end - pa_start, mode, noflush);
+					    pa_end - pa_start, mode, flags);
 					if (error != 0)
 						break;
 					/* Start physical address run. */
@@ -8132,7 +8146,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size
 		pa_end1 = MIN(pa_end, dmaplimit);
 		if (pa_start != pa_end1)
 			error = pmap_change_attr_locked(PHYS_TO_DMAP(pa_start),
-			    pa_end1 - pa_start, mode, noflush);
+			    pa_end1 - pa_start, mode, flags);
 	}
 
 	/*
@@ -8141,7 +8155,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size
 	 */
 	if (changed) {
 		pmap_invalidate_range(kernel_pmap, base, tmpva);
-		if (!noflush)
+		if ((flags & MAPDEV_FLUSHCACHE) != 0)
 			pmap_invalidate_cache_range(base, tmpva);
 	}
 	return (error);

Modified: head/sys/i386/i386/pmap.c
==============================================================================
--- head/sys/i386/i386/pmap.c	Sat Aug  3 01:06:17 2019	(r350550)
+++ head/sys/i386/i386/pmap.c	Sat Aug  3 01:36:05 2019	(r350551)
@@ -5404,10 +5404,12 @@ pmap_pde_attr(pd_entry_t *pde, int cache_bits)
  * NOT real memory.
  */
 static void *
-__CONCAT(PMTYPE, mapdev_attr)(vm_paddr_t pa, vm_size_t size, int mode)
+__CONCAT(PMTYPE, mapdev_attr)(vm_paddr_t pa, vm_size_t size, int mode,
+    int flags)
 {
 	struct pmap_preinit_mapping *ppim;
 	vm_offset_t va, offset;
+	vm_page_t m;
 	vm_size_t tmpsize;
 	int i;
 
@@ -5415,9 +5417,11 @@ __CONCAT(PMTYPE, mapdev_attr)(vm_paddr_t pa, vm_size_t
 	size = round_page(offset + size);
 	pa = pa & PG_FRAME;
 
-	if (pa < PMAP_MAP_LOW && pa + size <= PMAP_MAP_LOW)
+	if (pa < PMAP_MAP_LOW && pa + size <= PMAP_MAP_LOW) {
 		va = pa + PMAP_MAP_LOW;
-	else if (!pmap_initialized) {
+		if ((flags & MAPDEV_SETATTR) == 0)
+			return ((void *)(va + offset));
+	} else if (!pmap_initialized) {
 		va = 0;
 		for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
 			ppim = pmap_preinit_mapping + i;
@@ -5440,15 +5444,25 @@ __CONCAT(PMTYPE, mapdev_attr)(vm_paddr_t pa, vm_size_t
 		for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
 			ppim = pmap_preinit_mapping + i;
 			if (ppim->pa == pa && ppim->sz == size &&
-			    ppim->mode == mode)
+			    (ppim->mode == mode ||
+			    (flags & MAPDEV_SETATTR) == 0))
 				return ((void *)(ppim->va + offset));
 		}
 		va = kva_alloc(size);
 		if (va == 0)
 			panic("%s: Couldn't allocate KVA", __func__);
 	}
-	for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE)
+	for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE) {
+		if ((flags & MAPDEV_SETATTR) == 0 && pmap_initialized) {
+			m = PHYS_TO_VM_PAGE(pa);
+			if (m != NULL && VM_PAGE_TO_PHYS(m) == pa) {
+				pmap_kenter_attr(va + tmpsize, pa + tmpsize,
+				    m->md.pat_mode);
+				continue;
+			}
+		}
 		pmap_kenter_attr(va + tmpsize, pa + tmpsize, mode);
+	}
 	pmap_invalidate_range_int(kernel_pmap, va, va + tmpsize);
 	pmap_invalidate_cache_range(va, va + size);
 	return ((void *)(va + offset));

Modified: head/sys/i386/i386/pmap_base.c
==============================================================================
--- head/sys/i386/i386/pmap_base.c	Sat Aug  3 01:06:17 2019	(r350550)
+++ head/sys/i386/i386/pmap_base.c	Sat Aug  3 01:36:05 2019	(r350551)
@@ -776,21 +776,23 @@ void *
 pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
 {
 
-	return (pmap_methods_ptr->pm_mapdev_attr(pa, size, mode));
+	return (pmap_methods_ptr->pm_mapdev_attr(pa, size, mode,
+	    MAPDEV_SETATTR));
 }
 
 void *
 pmap_mapdev(vm_paddr_t pa, vm_size_t size)
 {
 
-	return (pmap_methods_ptr->pm_mapdev_attr(pa, size, PAT_UNCACHEABLE));
+	return (pmap_methods_ptr->pm_mapdev_attr(pa, size, PAT_UNCACHEABLE,
+	    MAPDEV_SETATTR));
 }
 
 void *
 pmap_mapbios(vm_paddr_t pa, vm_size_t size)
 {
 
-	return (pmap_methods_ptr->pm_mapdev_attr(pa, size, PAT_WRITE_BACK));
+	return (pmap_methods_ptr->pm_mapdev_attr(pa, size, PAT_WRITE_BACK, 0));
 }
 
 void

Modified: head/sys/i386/include/pmap_base.h
==============================================================================
--- head/sys/i386/include/pmap_base.h	Sat Aug  3 01:06:17 2019	(r350550)
+++ head/sys/i386/include/pmap_base.h	Sat Aug  3 01:36:05 2019	(r350551)
@@ -34,6 +34,9 @@
 #ifndef _MACHINE_PMAP_BASE_H_
 #define	_MACHINE_PMAP_BASE_H_
 
+/* Internal flags for pmap_mapdev_attr(). */
+#define	MAPDEV_SETATTR		0x0000001	/* Modify existing attrs. */
+
 struct pmap_methods {
 	void (*pm_ksetrw)(vm_offset_t);
 	void (*pm_remap_lower)(bool);
@@ -93,7 +96,7 @@ struct pmap_methods {
 	boolean_t (*pm_is_referenced)(vm_page_t);
 	void (*pm_remove_write)(vm_page_t);
 	int (*pm_ts_referenced)(vm_page_t);
-	void *(*pm_mapdev_attr)(vm_paddr_t, vm_size_t, int);
+	void *(*pm_mapdev_attr)(vm_paddr_t, vm_size_t, int, int);
 	void (*pm_unmapdev)(vm_offset_t, vm_size_t);
 	void (*pm_page_set_memattr)(vm_page_t, vm_memattr_t);
 	vm_paddr_t (*pm_extract)(pmap_t, vm_offset_t);



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