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Date: Fri, 28 Nov 2014 11:53:57 +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, x86@...nel.org, tglx@...utronix.de,
mingo@...hat.com, hpa@...or.com, andrew.cooper3@...rix.com
Cc: Juergen Gross <jgross@...e.com>
Subject: [PATCH V4 08/10] xen: Hide get_phys_to_machine() to be able to tune common path
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
soon as the switch to a linear mapped p2m list has been done.
Signed-off-by: Juergen Gross <jgross@...e.com>
Reviewed-by: David Vrabel <david.vrabel@...rix.com>
---
arch/x86/include/asm/xen/page.h | 26 ++++++++++++++++++++------
arch/x86/xen/mmu.c | 2 +-
arch/x86/xen/p2m.c | 6 +++---
3 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 28fa795..410a6ec 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -59,6 +59,21 @@ 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. No indicator
+ * bits (identity or foreign) are set.
+ * - __pfn_to_mfn() returns the found entry of the p2m table. A possibly set
+ * identity or foreign indicator will be still set. __pfn_to_mfn() is
+ * encapsulating get_phys_to_machine().
+ * - get_phys_to_machine() is to be called by __pfn_to_mfn() only to allow
+ * for future optimizations.
+ */
+static inline unsigned long __pfn_to_mfn(unsigned long pfn)
+{
+ return get_phys_to_machine(pfn);
+}
+
static inline unsigned long pfn_to_mfn(unsigned long pfn)
{
unsigned long mfn;
@@ -66,7 +81,7 @@ static inline unsigned long pfn_to_mfn(unsigned long pfn)
if (xen_feature(XENFEAT_auto_translated_physmap))
return pfn;
- mfn = get_phys_to_machine(pfn);
+ mfn = __pfn_to_mfn(pfn);
if (mfn != INVALID_P2M_ENTRY)
mfn &= ~(FOREIGN_FRAME_BIT | IDENTITY_FRAME_BIT);
@@ -79,7 +94,7 @@ static inline int phys_to_machine_mapping_valid(unsigned long pfn)
if (xen_feature(XENFEAT_auto_translated_physmap))
return 1;
- return get_phys_to_machine(pfn) != INVALID_P2M_ENTRY;
+ return __pfn_to_mfn(pfn) != INVALID_P2M_ENTRY;
}
static inline unsigned long mfn_to_pfn_no_overrides(unsigned long mfn)
@@ -113,7 +128,7 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
return mfn;
pfn = mfn_to_pfn_no_overrides(mfn);
- if (get_phys_to_machine(pfn) != mfn) {
+ if (__pfn_to_mfn(pfn) != mfn) {
/*
* If this appears to be a foreign mfn (because the pfn
* doesn't map back to the mfn), then check the local override
@@ -129,8 +144,7 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
* entry doesn't map back to the mfn and m2p_override doesn't have a
* valid entry for it.
*/
- if (pfn == ~0 &&
- get_phys_to_machine(mfn) == IDENTITY_FRAME(mfn))
+ if (pfn == ~0 && __pfn_to_mfn(mfn) == IDENTITY_FRAME(mfn))
pfn = mfn;
return pfn;
@@ -176,7 +190,7 @@ static inline unsigned long mfn_to_local_pfn(unsigned long mfn)
return mfn;
pfn = mfn_to_pfn(mfn);
- if (get_phys_to_machine(pfn) != mfn)
+ if (__pfn_to_mfn(pfn) != mfn)
return -1; /* force !pfn_valid() */
return pfn;
}
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 601914d..3e3f8f8 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -387,7 +387,7 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
unsigned long mfn;
if (!xen_feature(XENFEAT_auto_translated_physmap))
- mfn = get_phys_to_machine(pfn);
+ mfn = __pfn_to_mfn(pfn);
else
mfn = pfn;
/*
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index eddec40..8c3d8fb 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -787,7 +787,7 @@ static int m2p_add_override(unsigned long mfn, struct page *page,
* because mfn_to_pfn (that ends up being called by GUPF) will
* return the backend pfn rather than the frontend pfn. */
pfn = mfn_to_pfn_no_overrides(mfn);
- if (get_phys_to_machine(pfn) == mfn)
+ if (__pfn_to_mfn(pfn) == mfn)
set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
return 0;
@@ -967,7 +967,7 @@ static int m2p_remove_override(struct page *page,
* pfn again. */
mfn &= ~FOREIGN_FRAME_BIT;
pfn = mfn_to_pfn_no_overrides(mfn);
- if (get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
+ if (__pfn_to_mfn(pfn) == FOREIGN_FRAME(mfn) &&
m2p_find_override(mfn) == NULL)
set_phys_to_machine(pfn, mfn);
@@ -992,7 +992,7 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
}
for (i = 0; i < count; i++) {
- unsigned long mfn = get_phys_to_machine(page_to_pfn(pages[i]));
+ unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
unsigned long pfn = page_to_pfn(pages[i]);
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
--
2.1.2
--
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