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Subject[PATCH 02/24] xen: separate p2m allocation from setting
Date
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

When doing very early p2m setting, we need to separate setting
from allocation, so split things up accordingly.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/xen/mmu.c | 61 +++++++++++++++++++++++++++++++++++++--------------
arch/x86/xen/mmu.h | 3 ++
2 files changed, 47 insertions(+), 17 deletions(-)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index eceff87..d534986 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -233,47 +233,74 @@ unsigned long get_phys_to_machine(unsigned long pfn)
}
EXPORT_SYMBOL_GPL(get_phys_to_machine);

-static void alloc_p2m(unsigned long **pp, unsigned long *mfnp)
+/* install a new p2m_top page */
+bool install_p2mtop_page(unsigned long pfn, unsigned long *p)
{
- unsigned long *p;
+ unsigned topidx = p2m_top_index(pfn);
+ unsigned long **pfnp, *mfnp;
unsigned i;

- p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL);
- BUG_ON(p == NULL);
+ pfnp = &p2m_top[topidx];
+ mfnp = &p2m_top_mfn[topidx];

for (i = 0; i < P2M_ENTRIES_PER_PAGE; i++)
p[i] = INVALID_P2M_ENTRY;

- if (cmpxchg(pp, p2m_missing, p) != p2m_missing)
- free_page((unsigned long)p);
- else
+ if (cmpxchg(pfnp, p2m_missing, p) == p2m_missing) {
*mfnp = virt_to_mfn(p);
+ return true;
+ }
+
+ return false;
}

-void set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+static void alloc_p2m(unsigned long pfn)
{
- unsigned topidx, idx;
+ unsigned long *p;

- if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
- BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
- return;
- }
+ p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL);
+ BUG_ON(p == NULL);
+
+ if (!install_p2mtop_page(pfn, p))
+ free_page((unsigned long)p);
+}
+
+/* Try to install p2m mapping; fail if intermediate bits missing */
+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+ unsigned topidx, idx;

if (unlikely(pfn >= MAX_DOMAIN_PAGES)) {
BUG_ON(mfn != INVALID_P2M_ENTRY);
- return;
+ return true;
}

topidx = p2m_top_index(pfn);
if (p2m_top[topidx] == p2m_missing) {
- /* no need to allocate a page to store an invalid entry */
if (mfn == INVALID_P2M_ENTRY)
- return;
- alloc_p2m(&p2m_top[topidx], &p2m_top_mfn[topidx]);
+ return true;
+ return false;
}

idx = p2m_index(pfn);
p2m_top[topidx][idx] = mfn;
+
+ return true;
+}
+
+void set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+ if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
+ BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
+ return;
+ }
+
+ if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
+ alloc_p2m(pfn);
+
+ if (!__set_phys_to_machine(pfn, mfn))
+ BUG();
+ }
}

unsigned long arbitrary_virt_to_mfn(void *vaddr)
diff --git a/arch/x86/xen/mmu.h b/arch/x86/xen/mmu.h
index 24d1b44..da73026 100644
--- a/arch/x86/xen/mmu.h
+++ b/arch/x86/xen/mmu.h
@@ -11,6 +11,9 @@ enum pt_level {
};


+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
+bool install_p2mtop_page(unsigned long pfn, unsigned long *p);
+
void set_pte_mfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags);


--
1.6.0.6


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