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Subject[PATCH] xen: implement XENMEM_machphys_mapping
Date
From: Ian Campbell <ian.campbell@citrix.com>

This hypercall allows Xen to specify a non-default location for the
machine to physical mapping. This capability is used when running a 32
bit domain 0 on a 64 bit hypervisor to shrink the hypervisor hole to
exactly the size required.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/include/asm/xen/interface.h | 6 +++---
arch/x86/include/asm/xen/interface_32.h | 5 +++++
arch/x86/include/asm/xen/interface_64.h | 13 +------------
arch/x86/include/asm/xen/page.h | 7 ++++---
arch/x86/xen/enlighten.c | 7 +++++++
arch/x86/xen/mmu.c | 15 +++++++++++++++
include/xen/interface/memory.h | 13 +++++++++++++
7 files changed, 48 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/xen/interface.h b/arch/x86/include/asm/xen/interface.h
index e8506c1..1c10c88 100644
--- a/arch/x86/include/asm/xen/interface.h
+++ b/arch/x86/include/asm/xen/interface.h
@@ -61,9 +61,9 @@ DEFINE_GUEST_HANDLE(void);
#define HYPERVISOR_VIRT_START mk_unsigned_long(__HYPERVISOR_VIRT_START)
#endif

-#ifndef machine_to_phys_mapping
-#define machine_to_phys_mapping ((unsigned long *)HYPERVISOR_VIRT_START)
-#endif
+#define MACH2PHYS_VIRT_START mk_unsigned_long(__MACH2PHYS_VIRT_START)
+#define MACH2PHYS_VIRT_END mk_unsigned_long(__MACH2PHYS_VIRT_END)
+#define MACH2PHYS_NR_ENTRIES ((MACH2PHYS_VIRT_END-MACH2PHYS_VIRT_START)>>__MACH2PHYS_SHIFT)

/* Maximum number of virtual CPUs in multi-processor guests. */
#define MAX_VIRT_CPUS 32
diff --git a/arch/x86/include/asm/xen/interface_32.h b/arch/x86/include/asm/xen/interface_32.h
index 42a7e00..8413688 100644
--- a/arch/x86/include/asm/xen/interface_32.h
+++ b/arch/x86/include/asm/xen/interface_32.h
@@ -32,6 +32,11 @@
/* And the trap vector is... */
#define TRAP_INSTR "int $0x82"

+#define __MACH2PHYS_VIRT_START 0xF5800000
+#define __MACH2PHYS_VIRT_END 0xF6800000
+
+#define __MACH2PHYS_SHIFT 2
+
/*
* Virtual addresses beyond this are not modifiable by guest OSes. The
* machine->physical mapping table starts at this address, read-only.
diff --git a/arch/x86/include/asm/xen/interface_64.h b/arch/x86/include/asm/xen/interface_64.h
index 100d266..839a481 100644
--- a/arch/x86/include/asm/xen/interface_64.h
+++ b/arch/x86/include/asm/xen/interface_64.h
@@ -39,18 +39,7 @@
#define __HYPERVISOR_VIRT_END 0xFFFF880000000000
#define __MACH2PHYS_VIRT_START 0xFFFF800000000000
#define __MACH2PHYS_VIRT_END 0xFFFF804000000000
-
-#ifndef HYPERVISOR_VIRT_START
-#define HYPERVISOR_VIRT_START mk_unsigned_long(__HYPERVISOR_VIRT_START)
-#define HYPERVISOR_VIRT_END mk_unsigned_long(__HYPERVISOR_VIRT_END)
-#endif
-
-#define MACH2PHYS_VIRT_START mk_unsigned_long(__MACH2PHYS_VIRT_START)
-#define MACH2PHYS_VIRT_END mk_unsigned_long(__MACH2PHYS_VIRT_END)
-#define MACH2PHYS_NR_ENTRIES ((MACH2PHYS_VIRT_END-MACH2PHYS_VIRT_START)>>3)
-#ifndef machine_to_phys_mapping
-#define machine_to_phys_mapping ((unsigned long *)HYPERVISOR_VIRT_START)
-#endif
+#define __MACH2PHYS_SHIFT 3

/*
* int HYPERVISOR_set_segment_base(unsigned int which, unsigned long base)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 20c3872..95a3122 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -5,6 +5,7 @@
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/pfn.h>
+#include <linux/mm.h>

#include <asm/uaccess.h>
#include <asm/page.h>
@@ -35,6 +36,8 @@ typedef struct xpaddr {
#define MAX_DOMAIN_PAGES \
((unsigned long)((u64)CONFIG_XEN_MAX_DOMAIN_MEMORY * 1024 * 1024 * 1024 / PAGE_SIZE))

+extern unsigned long *machine_to_phys_mapping;
+extern unsigned int machine_to_phys_order;

extern unsigned long get_phys_to_machine(unsigned long pfn);
extern void set_phys_to_machine(unsigned long pfn, unsigned long mfn);
@@ -62,10 +65,8 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
if (xen_feature(XENFEAT_auto_translated_physmap))
return mfn;

-#if 0
if (unlikely((mfn >> machine_to_phys_order) != 0))
- return max_mapnr;
-#endif
+ return ~0;

pfn = 0;
/*
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index c12a3c8..62d229a 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -62,6 +62,11 @@ DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
enum xen_domain_type xen_domain_type = XEN_NATIVE;
EXPORT_SYMBOL_GPL(xen_domain_type);

+unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
+EXPORT_SYMBOL(machine_to_phys_mapping);
+unsigned int machine_to_phys_order;
+EXPORT_SYMBOL(machine_to_phys_order);
+
struct start_info *xen_start_info;
EXPORT_SYMBOL_GPL(xen_start_info);

@@ -890,6 +895,8 @@ asmlinkage void __init xen_start_kernel(void)

xen_setup_features();

+ xen_setup_machphys_mapping();
+
/* Install Xen paravirt ops */
pv_info = xen_info;
pv_init_ops = xen_init_ops;
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index f0d8190..367a7d2 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -57,6 +57,7 @@
#include <xen/page.h>
#include <xen/interface/xen.h>
#include <xen/interface/version.h>
+#include <xen/interface/memory.h>
#include <xen/hvc-console.h>

#include "multicalls.h"
@@ -1866,6 +1867,20 @@ static int xen_page_is_ram(unsigned long pfn)
return native_page_is_ram(pfn);
}

+__init void xen_setup_machphys_mapping(void)
+{
+ struct xen_machphys_mapping mapping;
+ unsigned long machine_to_phys_nr_ents;
+
+ if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) {
+ machine_to_phys_mapping = (unsigned long *)mapping.v_start;
+ machine_to_phys_nr_ents = mapping.max_mfn + 1;
+ } else {
+ machine_to_phys_nr_ents = MACH2PHYS_NR_ENTRIES;
+ }
+ machine_to_phys_order = fls(machine_to_phys_nr_ents - 1);
+}
+
__init void xen_ident_map_ISA(void)
{
unsigned long pa;
diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
index e6c6bcb..f548f7c 100644
--- a/include/xen/interface/memory.h
+++ b/include/xen/interface/memory.h
@@ -97,6 +97,19 @@ struct xen_machphys_mfn_list {
DEFINE_GUEST_HANDLE_STRUCT(xen_machphys_mfn_list);

/*
+ * Returns the location in virtual address space of the machine_to_phys
+ * mapping table. Architectures which do not have a m2p table, or which do not
+ * map it by default into guest address space, do not implement this command.
+ * arg == addr of xen_machphys_mapping_t.
+ */
+#define XENMEM_machphys_mapping 12
+struct xen_machphys_mapping {
+ unsigned long v_start, v_end; /* Start and end virtual addresses. */
+ unsigned long max_mfn; /* Maximum MFN that can be looked up. */
+};
+DEFINE_GUEST_HANDLE_STRUCT(xen_machphys_mapping_t);
+
+/*
* Sets the GPFN at which a particular page appears in the specified guest's
* pseudophysical address space.
* arg == addr of xen_add_to_physmap_t.
--
1.6.0.6


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