From 23e42a83c15ff793f09906ddfa40574155fbcc5d Mon Sep 17 00:00:00 2001
From: Andrew Turner <andrew@FreeBSD.org>
Date: Sun, 28 Jun 2020 15:03:07 +0000
Subject: [PATCH] Use EFI memory map to determine attributes for Acpi mappings
 on arm64.

AcpiOsMapMemory is used for device memory when e.g. an _INI method wants
to access physical memory, however, aarch64 pmap_mapbios is hardcoded to
writeback. Search for the correct memory type to use in pmap_mapbios.

Submitted by:	Greg V <greg_unrelenting.technology>
Differential Revision:	https://reviews.freebsd.org/D25201
---
 sys/arm64/arm64/machdep.c   | 44 ++++++++++++++++++++++++++++++++++++-
 sys/arm64/arm64/pmap.c      |  2 +-
 sys/arm64/include/machdep.h |  1 +
 3 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c
index f5950eae1aab..fa698c7dbdaa 100644
--- a/sys/arm64/arm64/machdep.c
+++ b/sys/arm64/arm64/machdep.c
@@ -120,6 +120,7 @@ int has_pan;
  * passed into the kernel and used by the EFI code to call runtime services.
  */
 vm_paddr_t efi_systbl_phys;
+static struct efi_map_header *efihdr;
 
 /* pagezero_* implementations are provided in support.S */
 void pagezero_simple(void *);
@@ -1071,11 +1072,52 @@ cache_setup(void)
 	}
 }
 
+int
+memory_mapping_mode(vm_paddr_t pa)
+{
+	struct efi_md *map, *p;
+	size_t efisz;
+	int ndesc, i;
+
+	if (efihdr == NULL)
+		return (VM_MEMATTR_WRITE_BACK);
+
+	/*
+	 * Memory map data provided by UEFI via the GetMemoryMap
+	 * Boot Services API.
+	 */
+	efisz = (sizeof(struct efi_map_header) + 0xf) & ~0xf;
+	map = (struct efi_md *)((uint8_t *)efihdr + efisz);
+
+	if (efihdr->descriptor_size == 0)
+		return (VM_MEMATTR_WRITE_BACK);
+	ndesc = efihdr->memory_size / efihdr->descriptor_size;
+
+	for (i = 0, p = map; i < ndesc; i++,
+	    p = efi_next_descriptor(p, efihdr->descriptor_size)) {
+		if (pa < p->md_phys ||
+		    pa >= p->md_phys + p->md_pages * EFI_PAGE_SIZE)
+			continue;
+		if (p->md_type == EFI_MD_TYPE_IOMEM ||
+		    p->md_type == EFI_MD_TYPE_IOPORT)
+			return (VM_MEMATTR_DEVICE);
+		else if ((p->md_attr & EFI_MD_ATTR_WB) != 0 ||
+		    p->md_type == EFI_MD_TYPE_RECLAIM)
+			return (VM_MEMATTR_WRITE_BACK);
+		else if ((p->md_attr & EFI_MD_ATTR_WT) != 0)
+			return (VM_MEMATTR_WRITE_THROUGH);
+		else if ((p->md_attr & EFI_MD_ATTR_WC) != 0)
+			return (VM_MEMATTR_WRITE_COMBINING);
+		break;
+	}
+
+	return (VM_MEMATTR_DEVICE);
+}
+
 void
 initarm(struct arm64_bootparams *abp)
 {
 	struct efi_fb *efifb;
-	struct efi_map_header *efihdr;
 	struct pcpu *pcpup;
 	char *env;
 #ifdef FDT
diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
index 43a16d185ed9..709d7d17c0c8 100644
--- a/sys/arm64/arm64/pmap.c
+++ b/sys/arm64/arm64/pmap.c
@@ -5449,7 +5449,7 @@ pmap_mapbios(vm_paddr_t pa, vm_size_t size)
 		/* L3 table is linked */
 		va = trunc_page(va);
 		pa = trunc_page(pa);
-		pmap_kenter(va, size, pa, VM_MEMATTR_WRITE_BACK);
+		pmap_kenter(va, size, pa, memory_mapping_mode(pa));
 	}
 
 	return ((void *)(va + offset));
diff --git a/sys/arm64/include/machdep.h b/sys/arm64/include/machdep.h
index 4a39020d8f73..f3bd5d6c4838 100644
--- a/sys/arm64/include/machdep.h
+++ b/sys/arm64/include/machdep.h
@@ -56,6 +56,7 @@ vm_offset_t parse_boot_param(struct arm64_bootparams *abp);
 #ifdef FDT
 void parse_fdt_bootargs(void);
 #endif
+int memory_mapping_mode(vm_paddr_t pa);
 extern void (*pagezero)(void *);
 
 #endif /* _KERNEL */