xen: add m2p override mechanism (448f2831) · Commits · 戴 / test

arch/x86/include/asm/xen/page.h

+13 −3

Original line number	Diff line number	Diff line
		@@ -42,6 +42,11 @@ extern unsigned int machine_to_phys_order;
		extern unsigned long get_phys_to_machine(unsigned long pfn);
		extern bool set_phys_to_machine(unsigned long pfn, unsigned long mfn);

		extern void m2p_add_override(unsigned long mfn, struct page *page);
		extern void m2p_remove_override(struct page *page);
		extern struct page *m2p_find_override(unsigned long mfn);
		extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn);

		static inline unsigned long pfn_to_mfn(unsigned long pfn)
		{
		unsigned long mfn;
		@@ -72,9 +77,6 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
		if (xen_feature(XENFEAT_auto_translated_physmap))
		return mfn;

		if (unlikely((mfn >> machine_to_phys_order) != 0))
		return ~0;

		pfn = 0;
		/*
		* The array access can fail (e.g., device space beyond end of RAM).
		@@ -83,6 +85,14 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
		*/
		__get_user(pfn, &machine_to_phys_mapping[mfn]);

		/*
		* If this appears to be a foreign mfn (because the pfn
		* doesn't map back to the mfn), then check the local override
		* table to see if there's a better pfn to use.
		*/
		if (get_phys_to_machine(pfn) != mfn)
		pfn = m2p_find_override_pfn(mfn, pfn);

		return pfn;
		}

arch/x86/xen/p2m.c

+80 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,8 @@

		#include <linux/init.h>
		#include <linux/module.h>
		#include <linux/list.h>
		#include <linux/hash.h>

		#include <asm/cache.h>
		#include <asm/setup.h>
		@@ -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;
		}

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