From eff4f7477b38b5b794ce1ede7766af1dcb6f8fde Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Wed, 9 Aug 2023 23:55:34 +0200
Subject: Fix missing DMA32 limit

Rumpdisk needs to allocate dma32 memory areas, so we do always need this
limit.

The non-Xen x86_64 case had a typo, and the 32bit PAE case didn't have
the DMA32 limit.

Also, we have to cope with VM_PAGE_DMA32_LIMIT being either above or below
VM_PAGE_DIRECTMAP_LIMIT depending on the cases.
---
 i386/i386/vm_param.h  |  8 +++++---
 i386/i386at/biosmem.c | 19 +++++++++++++++++++
 vm/vm_user.c          |  8 ++++++++
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/i386/i386/vm_param.h b/i386/i386/vm_param.h
index 05aeab33..19b5d9c1 100644
--- a/i386/i386/vm_param.h
+++ b/i386/i386/vm_param.h
@@ -143,7 +143,8 @@
 #define VM_PAGE_DIRECTMAP_LIMIT DECL_CONST(0x400000000000, UL)
 #define VM_PAGE_HIGHMEM_LIMIT   DECL_CONST(0x10000000000000, ULL)
 #else
-#define VM_PAGE_MAX_SEGS 3
+#define VM_PAGE_MAX_SEGS 4
+#define VM_PAGE_DMA32_LIMIT     DECL_CONST(0x100000000, UL)
 #define VM_PAGE_DIRECTMAP_LIMIT (VM_MAX_KERNEL_ADDRESS \
 				 - VM_MIN_KERNEL_ADDRESS \
 				 - VM_KERNEL_MAP_SIZE)
@@ -152,7 +153,7 @@
 #else /* MACH_XEN */
 #ifdef __LP64__
 #define VM_PAGE_MAX_SEGS 4
-#define VM_PAGE_DMA32_LIMIT     DECL_CONST(0x10000000, UL)
+#define VM_PAGE_DMA32_LIMIT     DECL_CONST(0x100000000, UL)
 #define VM_PAGE_DIRECTMAP_LIMIT (VM_MAX_KERNEL_ADDRESS \
 				 - VM_MIN_KERNEL_ADDRESS \
 				 - VM_KERNEL_MAP_SIZE + 1)
@@ -162,7 +163,8 @@
 				 - VM_MIN_KERNEL_ADDRESS \
 				 - VM_KERNEL_MAP_SIZE + 1)
 #ifdef PAE
-#define VM_PAGE_MAX_SEGS 3
+#define VM_PAGE_MAX_SEGS 4
+#define VM_PAGE_DMA32_LIMIT     DECL_CONST(0x100000000, UL)
 #define VM_PAGE_HIGHMEM_LIMIT   DECL_CONST(0x10000000000000, ULL)
 #else /* PAE */
 #define VM_PAGE_MAX_SEGS 3
diff --git a/i386/i386at/biosmem.c b/i386/i386at/biosmem.c
index 880989fe..6d0a03ae 100644
--- a/i386/i386at/biosmem.c
+++ b/i386/i386at/biosmem.c
@@ -692,7 +692,9 @@ biosmem_bootstrap_common(void)
     biosmem_set_segment(VM_PAGE_SEG_DMA, phys_start, phys_end);
 
     phys_start = VM_PAGE_DMA_LIMIT;
+
 #ifdef VM_PAGE_DMA32_LIMIT
+#if VM_PAGE_DMA32_LIMIT < VM_PAGE_DIRECTMAP_LIMIT
     phys_end = VM_PAGE_DMA32_LIMIT;
     error = biosmem_map_find_avail(&phys_start, &phys_end);
 
@@ -702,7 +704,9 @@ biosmem_bootstrap_common(void)
     biosmem_set_segment(VM_PAGE_SEG_DMA32, phys_start, phys_end);
 
     phys_start = VM_PAGE_DMA32_LIMIT;
+#endif
 #endif /* VM_PAGE_DMA32_LIMIT */
+
     phys_end = VM_PAGE_DIRECTMAP_LIMIT;
     error = biosmem_map_find_avail(&phys_start, &phys_end);
 
@@ -712,6 +716,21 @@ biosmem_bootstrap_common(void)
     biosmem_set_segment(VM_PAGE_SEG_DIRECTMAP, phys_start, phys_end);
 
     phys_start = VM_PAGE_DIRECTMAP_LIMIT;
+
+#ifdef VM_PAGE_DMA32_LIMIT
+#if VM_PAGE_DMA32_LIMIT > VM_PAGE_DIRECTMAP_LIMIT
+    phys_end = VM_PAGE_DMA32_LIMIT;
+    error = biosmem_map_find_avail(&phys_start, &phys_end);
+
+    if (error)
+        return;
+
+    biosmem_set_segment(VM_PAGE_SEG_DMA32, phys_start, phys_end);
+
+    phys_start = VM_PAGE_DMA32_LIMIT;
+#endif
+#endif /* VM_PAGE_DMA32_LIMIT */
+
     phys_end = VM_PAGE_HIGHMEM_LIMIT;
     error = biosmem_map_find_avail(&phys_start, &phys_end);
 
diff --git a/vm/vm_user.c b/vm/vm_user.c
index df597267..18f79eda 100644
--- a/vm/vm_user.c
+++ b/vm/vm_user.c
@@ -607,11 +607,19 @@ kern_return_t vm_allocate_contiguous(
 	selector = VM_PAGE_SEL_DMA;
 	if (pmax > VM_PAGE_DMA_LIMIT)
 #ifdef VM_PAGE_DMA32_LIMIT
+#if VM_PAGE_DMA32_LIMIT < VM_PAGE_DIRECTMAP_LIMIT
 		selector = VM_PAGE_SEL_DMA32;
 	if (pmax > VM_PAGE_DMA32_LIMIT)
+#endif
 #endif
 		selector = VM_PAGE_SEL_DIRECTMAP;
 	if (pmax > VM_PAGE_DIRECTMAP_LIMIT)
+#ifdef VM_PAGE_DMA32_LIMIT
+#if VM_PAGE_DMA32_LIMIT > VM_PAGE_DIRECTMAP_LIMIT
+		selector = VM_PAGE_SEL_DMA32;
+	if (pmax > VM_PAGE_DMA32_LIMIT)
+#endif
+#endif
 		selector = VM_PAGE_SEL_HIGHMEM;
 
 	size = vm_page_round(size);
-- 
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