linux-kernel - [PATCH 08/13] xen: add service function to copy physical memory areas

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Date:	Wed, 18 Feb 2015 07:52:01 +0100
From:	Juergen Gross <jgross@...e.com>
To:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	konrad.wilk@...cle.com, david.vrabel@...rix.com,
	boris.ostrovsky@...cle.com
Cc:	Juergen Gross <jgross@...e.com>
Subject: [PATCH 08/13] xen: add service function to copy physical memory areas

In case a pre-allocated memory area is to be moved in order to avoid
a conflict with the target E820 map we need a way to copy data between
physical addresses.

Add a function doing this via early_memremap().

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/xen/setup.c   | 29 +++++++++++++++++++++++++++++
 arch/x86/xen/xen-ops.h |  1 +
 2 files changed, 30 insertions(+)

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 9c49d71..eb219c1 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -766,6 +766,35 @@ phys_addr_t __init xen_find_free_area(phys_addr_t size)
 }
 
 /*
+ * Like memcpy, but with physical addresses for dest and src.
+ */
+void __init xen_phys_memcpy(phys_addr_t dest, phys_addr_t src, phys_addr_t n)
+{
+	phys_addr_t dest_off, src_off, dest_len, src_len, len;
+	void *from, *to;
+
+	while (n) {
+		dest_off = dest & ~PAGE_MASK;
+		src_off = src & ~PAGE_MASK;
+		dest_len = n;
+		if (dest_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off)
+			dest_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off;
+		src_len = n;
+		if (src_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off)
+			src_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off;
+		len = min(dest_len, src_len);
+		to = early_memremap(dest - dest_off, dest_len + dest_off);
+		from = early_memremap(src - src_off, src_len + src_off);
+		memcpy(to, from, len);
+		early_iounmap(to, dest_len + dest_off);
+		early_iounmap(from, src_len + src_off);
+		n -= len;
+		dest += len;
+		src += len;
+	}
+}
+
+/*
  * Reserve Xen mfn_list.
  * See comment above "struct start_info" in <xen/interface/xen.h>
  * We tried to make the the memblock_reserve more selective so
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 8181e01..9bf9df8 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -45,6 +45,7 @@ void __init xen_remap_memory(void);
 void __init xen_add_reserved_area(phys_addr_t start, phys_addr_t size,
 	int (*func)(phys_addr_t, phys_addr_t), int reserve);
 phys_addr_t __init xen_find_free_area(phys_addr_t size);
+void __init xen_phys_memcpy(phys_addr_t dest, phys_addr_t src, phys_addr_t n);
 char * __init xen_memory_setup(void);
 char * xen_auto_xlated_memory_setup(void);
 void __init xen_arch_setup(void);
-- 
2.1.4

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