From 448f2831934381e9d3c4d93e700ba7bbe14612dc Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 15 Dec 2010 13:19:33 +0000 Subject: xen: add m2p override mechanism Add a simple hashtable based mechanism to override some portions of the m2p, so that we can find out the pfn corresponding to an mfn of a granted page. In fact entries corresponding to granted pages in the m2p hold the original pfn value of the page in the source domain that granted it. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/p2m.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+) (limited to 'arch/x86/xen/p2m.c') diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 259ec3bb8b6f..8db19d50c467 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -27,6 +27,8 @@ #include #include +#include +#include #include #include @@ -37,6 +39,8 @@ #include "xen-ops.h" +static void __init m2p_override_init(void); + unsigned long xen_max_p2m_pfn __read_mostly; #define P2M_PER_PAGE (PAGE_SIZE / sizeof(unsigned long)) @@ -234,6 +238,8 @@ void __init xen_build_dynamic_phys_to_machine(void) p2m_top[topidx][mididx] = &mfn_list[pfn]; } + + m2p_override_init(); } unsigned long get_phys_to_machine(unsigned long pfn) @@ -374,3 +380,77 @@ bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) return true; } + +#define M2P_OVERRIDE_HASH_SHIFT 10 +#define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT) + +static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH); +static DEFINE_SPINLOCK(m2p_override_lock); + +static void __init m2p_override_init(void) +{ + unsigned i; + + m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH, + sizeof(unsigned long)); + + for (i = 0; i < M2P_OVERRIDE_HASH; i++) + INIT_LIST_HEAD(&m2p_overrides[i]); +} + +static unsigned long mfn_hash(unsigned long mfn) +{ + return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT); +} + +/* Add an MFN override for a particular page */ +void m2p_add_override(unsigned long mfn, struct page *page) +{ + unsigned long flags; + page->private = mfn; + + spin_lock_irqsave(&m2p_override_lock, flags); + list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); + spin_unlock_irqrestore(&m2p_override_lock, flags); +} + +void m2p_remove_override(struct page *page) +{ + unsigned long flags; + spin_lock_irqsave(&m2p_override_lock, flags); + list_del(&page->lru); + spin_unlock_irqrestore(&m2p_override_lock, flags); +} + +struct page *m2p_find_override(unsigned long mfn) +{ + unsigned long flags; + struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)]; + struct page *p, *ret; + + ret = NULL; + + spin_lock_irqsave(&m2p_override_lock, flags); + + list_for_each_entry(p, bucket, lru) { + if (p->private == mfn) { + ret = p; + break; + } + } + + spin_unlock_irqrestore(&m2p_override_lock, flags); + + return ret; +} + +unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn) +{ + struct page *p = m2p_find_override(mfn); + unsigned long ret = pfn; + + if (p) + ret = page_to_pfn(p); + + return ret; +} -- cgit v1.2.1