On Tue, Nov 11, 2014 at 06:43:44AM +0100, Juergen Gross wrote:
Today get_phys_to_machine() is always called when the mfn for a pfn
is to be obtained. Add a wrapper __pfn_to_mfn() as inline function
to be able to avoid calling get_phys_to_machine() when possible as
s/when/where/
soon as the switch to a linear mapped p2m list has been done.
But your inline function still calls get_phys_to_machine?
Signed-off-by: Juergen Gross jgr...@suse.com
---
arch/x86/include/asm/xen/page.h | 27 +--
arch/x86/xen/mmu.c | 2 +-
arch/x86/xen/p2m.c | 6 +++---
3 files changed, 25 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 28fa795..07d8a7b 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -59,6 +59,22 @@ extern int clear_foreign_p2m_mapping(struct
gnttab_unmap_grant_ref *unmap_ops,
struct page **pages, unsigned int count);
extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long
pfn);
+/*
+ * When to use pfn_to_mfn(), __pfn_to_mfn() or get_phys_to_machine():
+ * - pfn_to_mfn() returns either INVALID_P2M_ENTRY or the mfn. In case of an
+ * identity entry the identity indicator will be cleared.
Why don't you say : In case of identity PFN the same PFN is returned.
But you did miss that also the FOREIGN_FRAME_BIT is cleared.
+ * - __pfn_to_mfn() returns the found entry of the p2m table. A possibly set
s/of the/in the/
+ * identity indicator will be still set. __pfn_to_mfn() is encapsulating
.. be still set if the PFN is an identity one.
+ * get_phys_to_machine() and might skip that function if possible to speed
+ * up the common path.
How is is skipping that function? The patch below does no such thing?
+ * - get_phys_to_machine() is basically the same as __pfn_to_mfn(), but
+ * without any short cuts for the common fast path.
Right. Perhpas we should call it 'slow_p2m' instead of the
'get_phys_to_machine'.
+ */
+static inline unsigned long __pfn_to_mfn(unsigned long pfn)
+{
+ return get_phys_to_machine(pfn);
+}
+
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