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@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index a4a265fcab173e72d9cebff046817ea99410781b..57aba6ba6f92df2162262ae9dd50a11fa527b49f 100644 (file)
--- 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 601914d2b0a8ea25beb9991453a059d3395a1fcd..3e3f8f8c3a301624885761358b1406e8f5122de6 100644 (file)
--- 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 eddec40a4c204bbc35ad272abfd500025c3dc6a8..8c3d8fbbba935d9f03a8a12e1abff19b21a193d1 100644 (file)
--- 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)) {