xen: make phys_to_machine structure dynamic
We now support the use of memory hotplug, so the physical to machine
page mapping structure must be dynamic. This is implemented as a
two-level radix tree structure, which allows us to efficiently
incrementally allocate memory for the p2m table as new pages are
added.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 5c0635a..73d3c84 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1221,7 +1221,7 @@
/* Get mfn list */
if (!xen_feature(XENFEAT_auto_translated_physmap))
- phys_to_machine_mapping = (unsigned long *)xen_start_info->mfn_list;
+ xen_build_dynamic_phys_to_machine();
pgd = (pgd_t *)xen_start_info->pt_base;
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 07c2653..c3b27de 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -56,6 +56,91 @@
#include "multicalls.h"
#include "mmu.h"
+/*
+ * This should probably be a config option. On 32-bit, it costs 1
+ * page/gig of memory; on 64-bit its 2 pages/gig. If we want it to be
+ * completely unbounded we can add another level to the p2m structure.
+ */
+#define MAX_GUEST_PAGES (16ull * 1024*1024*1024 / PAGE_SIZE)
+#define P2M_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(unsigned long))
+
+static unsigned long *p2m_top[MAX_GUEST_PAGES / P2M_ENTRIES_PER_PAGE];
+
+static inline unsigned p2m_top_index(unsigned long pfn)
+{
+ BUG_ON(pfn >= MAX_GUEST_PAGES);
+ return pfn / P2M_ENTRIES_PER_PAGE;
+}
+
+static inline unsigned p2m_index(unsigned long pfn)
+{
+ return pfn % P2M_ENTRIES_PER_PAGE;
+}
+
+void __init xen_build_dynamic_phys_to_machine(void)
+{
+ unsigned pfn;
+ unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
+
+ BUG_ON(xen_start_info->nr_pages >= MAX_GUEST_PAGES);
+
+ for(pfn = 0;
+ pfn < xen_start_info->nr_pages;
+ pfn += P2M_ENTRIES_PER_PAGE) {
+ unsigned topidx = p2m_top_index(pfn);
+
+ p2m_top[topidx] = &mfn_list[pfn];
+ }
+}
+
+unsigned long get_phys_to_machine(unsigned long pfn)
+{
+ unsigned topidx, idx;
+
+ topidx = p2m_top_index(pfn);
+ if (p2m_top[topidx] == NULL)
+ return INVALID_P2M_ENTRY;
+
+ idx = p2m_index(pfn);
+ return p2m_top[topidx][idx];
+}
+
+static void alloc_p2m(unsigned long **pp)
+{
+ unsigned long *p;
+ unsigned i;
+
+ p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL);
+ BUG_ON(p == NULL);
+
+ for(i = 0; i < P2M_ENTRIES_PER_PAGE; i++)
+ p[i] = INVALID_P2M_ENTRY;
+
+ if (cmpxchg(pp, NULL, p) != NULL)
+ free_page((unsigned long)p);
+}
+
+void set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+ unsigned topidx, idx;
+
+ if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
+ BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
+ return;
+ }
+
+ topidx = p2m_top_index(pfn);
+ if (p2m_top[topidx] == NULL) {
+ /* no need to allocate a page to store an invalid entry */
+ if (mfn == INVALID_P2M_ENTRY)
+ return;
+ alloc_p2m(&p2m_top[topidx]);
+ }
+
+ idx = p2m_index(pfn);
+ p2m_top[topidx][idx] = mfn;
+}
+
xmaddr_t arbitrary_virt_to_machine(unsigned long address)
{
unsigned int level;
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 82517e4..37f8f0b 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -27,8 +27,6 @@
extern const char xen_hypervisor_callback[];
extern const char xen_failsafe_callback[];
-unsigned long *phys_to_machine_mapping;
-EXPORT_SYMBOL(phys_to_machine_mapping);
/**
* machine_specific_memory_setup - Hook for machine specific memory setup.
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index f1063ae..7bdc8c5 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -22,6 +22,8 @@
void __init xen_init_IRQ(void);
void xen_enable_sysenter(void);
+void __init xen_build_dynamic_phys_to_machine(void);
+
void xen_setup_timer(int cpu);
void xen_setup_cpu_clockevents(void);
unsigned long xen_cpu_khz(void);