linux-kernel - [PATCHv2 09/10] x86/xen: export xen_alloc_p2m

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Date:	Fri, 24 Jul 2015 12:47:47 +0100
From:	David Vrabel <david.vrabel@...rix.com>
To:	<xen-devel@...ts.xenproject.org>
CC:	David Vrabel <david.vrabel@...rix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	Daniel Kiper <daniel.kiper@...cle.com>
Subject: [PATCHv2 09/10] x86/xen: export xen_alloc_p2m_entry()

Rename alloc_p2m() to xen_alloc_p2m_entry() and export it.

This is useful for ensuring that a p2m entry is allocated (i.e., not a
shared missing or identity entry) so that subsequent set_phys_to_machine()
calls will require no further allocations.

Signed-off-by: David Vrabel <david.vrabel@...rix.com>
---
 arch/x86/include/asm/xen/page.h |  2 ++
 arch/x86/xen/p2m.c              | 16 ++++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index c44a5d5..960b380 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -45,6 +45,8 @@ extern unsigned long *xen_p2m_addr;
 extern unsigned long  xen_p2m_size;
 extern unsigned long  xen_max_p2m_pfn;
 
+extern int xen_alloc_p2m_entry(unsigned long pfn);
+
 extern unsigned long get_phys_to_machine(unsigned long pfn);
 extern bool set_phys_to_machine(unsigned long pfn, unsigned long mfn);
 extern bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 8b7f18e..ef93ccf 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -503,7 +503,7 @@ static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
  * the new pages are installed with cmpxchg; if we lose the race then
  * simply free the page we allocated and use the one that's there.
  */
-static bool alloc_p2m(unsigned long pfn)
+int xen_alloc_p2m_entry(unsigned long pfn)
 {
 	unsigned topidx, mididx;
 	unsigned long *top_mfn_p, *mid_mfn;
@@ -524,7 +524,7 @@ static bool alloc_p2m(unsigned long pfn)
 		/* PMD level is missing, allocate a new one */
 		ptep = alloc_p2m_pmd(addr, pte_pg);
 		if (!ptep)
-			return false;
+			return -ENOMEM;
 	}
 
 	if (p2m_top_mfn) {
@@ -541,7 +541,7 @@ static bool alloc_p2m(unsigned long pfn)
 
 			mid_mfn = alloc_p2m_page();
 			if (!mid_mfn)
-				return false;
+				return -ENOMEM;
 
 			p2m_mid_mfn_init(mid_mfn, p2m_missing);
 
@@ -567,7 +567,7 @@ static bool alloc_p2m(unsigned long pfn)
 
 		p2m = alloc_p2m_page();
 		if (!p2m)
-			return false;
+			return -ENOMEM;
 
 		if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
 			p2m_init(p2m);
@@ -590,8 +590,9 @@ static bool alloc_p2m(unsigned long pfn)
 			free_p2m_page(p2m);
 	}
 
-	return true;
+	return 0;
 }
+EXPORT_SYMBOL(xen_alloc_p2m);
 
 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
 				      unsigned long pfn_e)
@@ -648,7 +649,10 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 {
 	if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
-		if (!alloc_p2m(pfn))
+		int ret;
+
+		ret = xen_alloc_p2m_entry(pfn);
+		if (ret < 0)
 			return false;
 
 		return __set_phys_to_machine(pfn, mfn);
-- 
2.1.4

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