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/include/asm/xen/page.h | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'arch/x86/include') diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index 8760cc60a21c..50f0a0f6bd6a 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -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; } -- cgit v1.2.3 From 87f1d40a706bdebdc8f959b9ac291d0d8fdfcc7e Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Mon, 13 Dec 2010 14:42:30 +0000 Subject: xen p2m: clear the old pte when adding a page to m2p_override When adding a page to m2p_override we change the p2m of the page so we need to also clear the old pte of the kernel linear mapping because it doesn't correspond anymore. When we remove the page from m2p_override we restore the original p2m of the page and we also restore the old pte of the kernel linear mapping. Before changing the p2m mappings in m2p_add_override and m2p_remove_override, check that the page passed as argument is valid and return an error if it is not. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/include/asm/xen/page.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/include') diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index 50f0a0f6bd6a..f25bdf238a33 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -42,8 +42,8 @@ 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 int m2p_add_override(unsigned long mfn, struct page *page); +extern int 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); -- cgit v1.2.3