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Subject[PATCH 08/16] xen/dom0: Use host E820 map
Date
From: Ian Campbell <ian.campbell@citrix.com>

Unlike the non-paravirt Xen port we do not have distinct psuedo-physical
and I/O memory resource-spaces and therefore resources in the two
can clash. Fix this by registering a memory map which matches the
underlying I/O map. Currently this wastes the memory in the reserved
regions. Eventually we should remap this memory to the end of the
address space.

[ Impact: synthesize virtual E820 using real one as template ]

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/xen/setup.c | 45 +++++++++++++++++++++++++++++++++++++--
include/xen/interface/memory.h | 29 +++++++++++++++++++++++++
2 files changed, 71 insertions(+), 3 deletions(-)
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index dc55171..805ae53 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -19,6 +19,7 @@

#include <xen/page.h>
#include <xen/interface/callback.h>
+#include <xen/interface/memory.h>
#include <xen/interface/physdev.h>
#include <xen/features.h>

@@ -36,16 +37,54 @@ extern void xen_syscall32_target(void);
/**
* machine_specific_memory_setup - Hook for machine specific memory setup.
**/
-
char * __init xen_memory_setup(void)
{
unsigned long max_pfn = xen_start_info->nr_pages;
+ unsigned long long mem_end;
+ int rc;
+ struct xen_memory_map memmap;
+ /*
+ * This is rather large for a stack variable but this early in
+ * the boot process we know we have plenty slack space.
+ */
+ struct e820entry map[E820MAX];
+ int op = xen_initial_domain() ?
+ XENMEM_machine_memory_map :
+ XENMEM_memory_map;
+ int i;

max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
+ mem_end = PFN_PHYS((u64)max_pfn);
+
+ memmap.nr_entries = E820MAX;
+ set_xen_guest_handle(memmap.buffer, map);
+
+ rc = HYPERVISOR_memory_op(op, &memmap);
+ if (rc == -ENOSYS) {
+ memmap.nr_entries = 1;
+ map[0].addr = 0ULL;
+ map[0].size = mem_end;
+ /* 8MB slack (to balance backend allocations). */
+ map[0].size += 8ULL << 20;
+ map[0].type = E820_RAM;
+ rc = 0;
+ }
+ BUG_ON(rc);

e820.nr_map = 0;
-
- e820_add_region(0, PFN_PHYS((u64)max_pfn), E820_RAM);
+ for (i = 0; i < memmap.nr_entries; i++) {
+ unsigned long long end = map[i].addr + map[i].size;
+ if (map[i].type == E820_RAM) {
+ if (map[i].addr > mem_end)
+ continue;
+ if (end > mem_end) {
+ /* Truncate region to max_mem. */
+ map[i].size -= end - mem_end;
+ }
+ }
+ if (map[i].size > 0)
+ e820_add_region(map[i].addr, map[i].size, map[i].type);
+ }

/*
* Even though this is normal, usable memory under Xen, reserve
diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
index af36ead..e6c6bcb 100644
--- a/include/xen/interface/memory.h
+++ b/include/xen/interface/memory.h
@@ -142,4 +142,33 @@ struct xen_translate_gpfn_list {
};
DEFINE_GUEST_HANDLE_STRUCT(xen_translate_gpfn_list);

+/*
+ * Returns the pseudo-physical memory map as it was when the domain
+ * was started (specified by XENMEM_set_memory_map).
+ * arg == addr of struct xen_memory_map.
+ */
+#define XENMEM_memory_map 9
+struct xen_memory_map {
+ /*
+ * On call the number of entries which can be stored in buffer. On
+ * return the number of entries which have been stored in
+ * buffer.
+ */
+ unsigned int nr_entries;
+
+ /*
+ * Entries in the buffer are in the same format as returned by the
+ * BIOS INT 0x15 EAX=0xE820 call.
+ */
+ GUEST_HANDLE(void) buffer;
+};
+DEFINE_GUEST_HANDLE_STRUCT(xen_memory_map);
+
+/*
+ * Returns the real physical memory map. Passes the same structure as
+ * XENMEM_memory_map.
+ * arg == addr of struct xen_memory_map.
+ */
+#define XENMEM_machine_memory_map 10
+
#endif /* __XEN_PUBLIC_MEMORY_H__ */
--
1.6.0.6


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