Re: [PATCH v9 08/27] arm/x86/vmap: Add v[z|m]alloc_xen and vm_init_type

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

> With vm_alloc() getting removed, vm_free() should get removed
> here too. And with that, vm_alloc_type() and vm_free_type() can
> then just become vm_alloc() and vm_free() respectively (as static
> internal functions).

Please take a look at this inline one:

From 1c133365d98a02c8f5131cdcde11960623fa247a Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Tue, 26 Apr 2016 14:03:06 -0400
Subject: [PATCH] arm/x86/vmap: Add v[z|m]alloc_xen and vm_init_type

For those users who want to use the virtual addresses that
are in the hypervisor's code/data region address space -
these three new functions allow that.

Implementation wise the vmap API keeps track of two virtual
address regions now:
 a) VMAP_VIRT_START
 b) Any provided virtual address space (need start and end).

The a) one is the default one and the existing behavior
for users of vmalloc, vmap, etc is the same.

If however one wishes to use the b) one only has to use
the vm_init_type to initialize and the v[m|z]alloc_xen to utilize
it (vfree and vunmap are capable of searching both address spaces).

This allows users (such as xSplice) to provide their own
mechanism to change the the page flags, and also use virtual
addresses closer to the hypervisor virtual addresses (at least
on x86) while not having to deal with the allocation of
pages.

For example of users, see patch titled "xsplice: Implement payload
loading", where we parse the payload's ELF relocations - which
is defined to be signed 32-bit (on x86) (max displacement hence
is 2GB virtual space, ARM32 is 128MB). The displacement of the
hypervisor virtual addresses to the vmalloc (on x86)
is more than 32-bits - which means that ELF relocations would
truncate the 34 and 33th bit. Hence this alternate API.

We also add add extra checks in case the b) range has not been
initialized.

Part of this patch also removes 'vm_alloc' and 'vm_free'
decleration as we do not have any users of it.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Suggested-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien.grall@arm.com> [ARM]

---
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Tim Deegan <tim@xen.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Julien Grall <julien.grall@arm.com>

v4: New patch.
v5: Update per Jan's comments.
v6: Drop the stray parentheses on typedefs.
    Ditch the vunmap callback. Stash away the virtual addresses in lists.
    Ditch the vmap callback. Just provide virtual address.
    Ditch the vmalloc_range. Require users of alternative virtual address
    to call vmap_init_type first.
v7: Don't expose the vmalloc_type and such. Instead provide an wrapper
    called vmalloc_xen for those.
    Rename the enum, change one of the names.
    Moved the vunmap_type around in c file so we don't have to declare
    it in the header.
v9: Remove the vunmap_xen, removed vm_alloc from header.
    Add vzalloc_xen
v10:
    Properly ASSERT on ranges
    Make vm_free and vunmap automatically detect the right va space.
    Remove from header vm_free. Rename vm_alloc_type and vm_free_type
    to  vm_alloc and vm_free respectively.
---
 xen/arch/arm/kernel.c  |   2 +-
 xen/arch/arm/mm.c      |   2 +-
 xen/arch/x86/mm.c      |   2 +-
 xen/common/vmap.c      | 212 +++++++++++++++++++++++++++++++------------------
 xen/drivers/acpi/osl.c |   2 +-
 xen/include/xen/vmap.h |  22 +++--
 6 files changed, 156 insertions(+), 86 deletions(-)

diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index 61808ac..9871bd9 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -299,7 +299,7 @@ static __init int kernel_decompress(struct bootmodule *mod)
         return -ENOMEM;
     }
     mfn = _mfn(page_to_mfn(pages));
-    output = __vmap(&mfn, 1 << kernel_order_out, 1, 1, PAGE_HYPERVISOR);
+    output = __vmap(&mfn, 1 << kernel_order_out, 1, 1, PAGE_HYPERVISOR, VMAP_DEFAULT);
 
     rc = perform_gunzip(output, input, size);
     clean_dcache_va_range(output, output_size);
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 7065c3e..94ea054 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -807,7 +807,7 @@ void *ioremap_attr(paddr_t pa, size_t len, unsigned int attributes)
     mfn_t mfn = _mfn(PFN_DOWN(pa));
     unsigned int offs = pa & (PAGE_SIZE - 1);
     unsigned int nr = PFN_UP(offs + len);
-    void *ptr = __vmap(&mfn, nr, 1, 1, attributes);
+    void *ptr = __vmap(&mfn, nr, 1, 1, attributes, VMAP_DEFAULT);
 
     if ( ptr == NULL )
         return NULL;
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index a42097f..2bb920b 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -6179,7 +6179,7 @@ void __iomem *ioremap(paddr_t pa, size_t len)
         unsigned int offs = pa & (PAGE_SIZE - 1);
         unsigned int nr = PFN_UP(offs + len);
 
-        va = __vmap(&mfn, nr, 1, 1, PAGE_HYPERVISOR_NOCACHE) + offs;
+        va = __vmap(&mfn, nr, 1, 1, PAGE_HYPERVISOR_NOCACHE, VMAP_DEFAULT) + offs;
     }
 
     return (void __force __iomem *)va;
diff --git a/xen/common/vmap.c b/xen/common/vmap.c
index 134eda0..9c8782c 100644
--- a/xen/common/vmap.c
+++ b/xen/common/vmap.c
@@ -10,40 +10,43 @@
 #include <asm/page.h>
 
 static DEFINE_SPINLOCK(vm_lock);
-static void *__read_mostly vm_base;
-#define vm_bitmap ((unsigned long *)vm_base)
+static void *__read_mostly vm_base[VMAP_REGION_NR];
+#define vm_bitmap(x) ((unsigned long *)vm_base[x])
 /* highest allocated bit in the bitmap */
-static unsigned int __read_mostly vm_top;
+static unsigned int __read_mostly vm_top[VMAP_REGION_NR];
 /* total number of bits in the bitmap */
-static unsigned int __read_mostly vm_end;
+static unsigned int __read_mostly vm_end[VMAP_REGION_NR];
 /* lowest known clear bit in the bitmap */
-static unsigned int vm_low;
+static unsigned int vm_low[VMAP_REGION_NR];
 
-void __init vm_init(void)
+void __init vm_init_type(enum vmap_region type, void *start, void *end)
 {
     unsigned int i, nr;
     unsigned long va;
 
-    vm_base = (void *)VMAP_VIRT_START;
-    vm_end = PFN_DOWN(arch_vmap_virt_end() - vm_base);
-    vm_low = PFN_UP((vm_end + 7) / 8);
-    nr = PFN_UP((vm_low + 7) / 8);
-    vm_top = nr * PAGE_SIZE * 8;
+    ASSERT(!vm_base[type]);
 
-    for ( i = 0, va = (unsigned long)vm_bitmap; i < nr; ++i, va += PAGE_SIZE )
+    vm_base[type] = start;
+    vm_end[type] = PFN_DOWN(end - start);
+    vm_low[type]= PFN_UP((vm_end[type] + 7) / 8);
+    nr = PFN_UP((vm_low[type] + 7) / 8);
+    vm_top[type] = nr * PAGE_SIZE * 8;
+
+    for ( i = 0, va = (unsigned long)vm_bitmap(type); i < nr; ++i, va += PAGE_SIZE )
     {
         struct page_info *pg = alloc_domheap_page(NULL, 0);
 
         map_pages_to_xen(va, page_to_mfn(pg), 1, PAGE_HYPERVISOR);
         clear_page((void *)va);
     }
-    bitmap_fill(vm_bitmap, vm_low);
+    bitmap_fill(vm_bitmap(type), vm_low[type]);
 
     /* Populate page tables for the bitmap if necessary. */
-    populate_pt_range(va, 0, vm_low - nr);
+    populate_pt_range(va, 0, vm_low[type] - nr);
 }
 
-void *vm_alloc(unsigned int nr, unsigned int align)
+static void *vm_alloc(unsigned int nr, unsigned int align,
+                      enum vmap_region t)
 {
     unsigned int start, bit;
 
@@ -52,27 +55,31 @@ void *vm_alloc(unsigned int nr, unsigned int align)
     else if ( align & (align - 1) )
         align &= -align;
 
+    ASSERT((t >= VMAP_DEFAULT) && (t < VMAP_REGION_NR));
+    if ( !vm_base[t] )
+        return NULL;
+
     spin_lock(&vm_lock);
     for ( ; ; )
     {
         struct page_info *pg;
 
-        ASSERT(vm_low == vm_top || !test_bit(vm_low, vm_bitmap));
-        for ( start = vm_low; start < vm_top; )
+        ASSERT(vm_low[t] == vm_top[t] || !test_bit(vm_low[t], vm_bitmap(t)));
+        for ( start = vm_low[t]; start < vm_top[t]; )
         {
-            bit = find_next_bit(vm_bitmap, vm_top, start + 1);
-            if ( bit > vm_top )
-                bit = vm_top;
+            bit = find_next_bit(vm_bitmap(t), vm_top[t], start + 1);
+            if ( bit > vm_top[t] )
+                bit = vm_top[t];
             /*
              * Note that this skips the first bit, making the
              * corresponding page a guard one.
              */
             start = (start + align) & ~(align - 1);
-            if ( bit < vm_top )
+            if ( bit < vm_top[t] )
             {
                 if ( start + nr < bit )
                     break;
-                start = find_next_zero_bit(vm_bitmap, vm_top, bit + 1);
+                start = find_next_zero_bit(vm_bitmap(t), vm_top[t], bit + 1);
             }
             else
             {
@@ -82,12 +89,12 @@ void *vm_alloc(unsigned int nr, unsigned int align)
             }
         }
 
-        if ( start < vm_top )
+        if ( start < vm_top[t] )
             break;
 
         spin_unlock(&vm_lock);
 
-        if ( vm_top >= vm_end )
+        if ( vm_top[t] >= vm_end[t] )
             return NULL;
 
         pg = alloc_domheap_page(NULL, 0);
@@ -96,23 +103,23 @@ void *vm_alloc(unsigned int nr, unsigned int align)
 
         spin_lock(&vm_lock);
 
-        if ( start >= vm_top )
+        if ( start >= vm_top[t] )
         {
-            unsigned long va = (unsigned long)vm_bitmap + vm_top / 8;
+            unsigned long va = (unsigned long)vm_bitmap(t) + vm_top[t] / 8;
 
             if ( !map_pages_to_xen(va, page_to_mfn(pg), 1, PAGE_HYPERVISOR) )
             {
                 clear_page((void *)va);
-                vm_top += PAGE_SIZE * 8;
-                if ( vm_top > vm_end )
-                    vm_top = vm_end;
+                vm_top[t] += PAGE_SIZE * 8;
+                if ( vm_top[t] > vm_end[t] )
+                    vm_top[t] = vm_end[t];
                 continue;
             }
         }
 
         free_domheap_page(pg);
 
-        if ( start >= vm_top )
+        if ( start >= vm_top[t] )
         {
             spin_unlock(&vm_lock);
             return NULL;
@@ -120,47 +127,58 @@ void *vm_alloc(unsigned int nr, unsigned int align)
     }
 
     for ( bit = start; bit < start + nr; ++bit )
-        __set_bit(bit, vm_bitmap);
-    if ( bit < vm_top )
-        ASSERT(!test_bit(bit, vm_bitmap));
+        __set_bit(bit, vm_bitmap(t));
+    if ( bit < vm_top[t] )
+        ASSERT(!test_bit(bit, vm_bitmap(t)));
     else
-        ASSERT(bit == vm_top);
-    if ( start <= vm_low + 2 )
-        vm_low = bit;
+        ASSERT(bit == vm_top[t]);
+    if ( start <= vm_low[t] + 2 )
+        vm_low[t] = bit;
     spin_unlock(&vm_lock);
 
-    return vm_base + start * PAGE_SIZE;
+    return vm_base[t] + start * PAGE_SIZE;
 }
 
-static unsigned int vm_index(const void *va)
+static unsigned int vm_index(const void *va, enum vmap_region type)
 {
     unsigned long addr = (unsigned long)va & ~(PAGE_SIZE - 1);
     unsigned int idx;
+    unsigned long start = (unsigned long)vm_base[type];
 
-    if ( addr < VMAP_VIRT_START + (vm_end / 8) ||
-         addr >= VMAP_VIRT_START + vm_top * PAGE_SIZE )
+    if ( !start )
         return 0;
 
-    idx = PFN_DOWN(va - vm_base);
-    return !test_bit(idx - 1, vm_bitmap) &&
-           test_bit(idx, vm_bitmap) ? idx : 0;
+    if ( addr < start + (vm_end[type] / 8) ||
+         addr >= start + vm_top[type] * PAGE_SIZE )
+        return 0;
+
+    idx = PFN_DOWN(va - vm_base[type]);
+    return !test_bit(idx - 1, vm_bitmap(type)) &&
+           test_bit(idx, vm_bitmap(type)) ? idx : 0;
 }
 
-static unsigned int vm_size(const void *va)
+static unsigned int vm_size(const void *va, enum vmap_region type)
 {
-    unsigned int start = vm_index(va), end;
+    unsigned int start = vm_index(va, type), end;
 
     if ( !start )
         return 0;
 
-    end = find_next_zero_bit(vm_bitmap, vm_top, start + 1);
+    end = find_next_zero_bit(vm_bitmap(type), vm_top[type], start + 1);
 
-    return min(end, vm_top) - start;
+    return min(end, vm_top[type]) - start;
 }
 
-void vm_free(const void *va)
+static void vm_free(const void *va)
 {
-    unsigned int bit = vm_index(va);
+    enum vmap_region type = VMAP_DEFAULT;
+    unsigned int bit = vm_index(va, type);
+
+    if ( !bit )
+    {
+        type = VMAP_XEN;
+        bit = vm_index(va, type);
+    }
 
     if ( !bit )
     {
@@ -169,29 +187,55 @@ void vm_free(const void *va)
     }
 
     spin_lock(&vm_lock);
-    if ( bit < vm_low )
+    if ( bit < vm_low[type] )
     {
-        vm_low = bit - 1;
-        while ( !test_bit(vm_low - 1, vm_bitmap) )
-            --vm_low;
+        vm_low[type] = bit - 1;
+        while ( !test_bit(vm_low[type] - 1, vm_bitmap(type)) )
+            --vm_low[type];
     }
-    while ( __test_and_clear_bit(bit, vm_bitmap) )
-        if ( ++bit == vm_top )
+    while ( __test_and_clear_bit(bit, vm_bitmap(type)) )
+        if ( ++bit == vm_top[type] )
             break;
     spin_unlock(&vm_lock);
 }
 
+static void vunmap_pages(const void *va, unsigned int pages)
+{
+#ifndef _PAGE_NONE
+    unsigned long addr = (unsigned long)va;
+
+    destroy_xen_mappings(addr, addr + PAGE_SIZE * pages);
+#else /* Avoid tearing down intermediate page tables. */
+    map_pages_to_xen((unsigned long)va, 0, pages, _PAGE_NONE);
+#endif
+    vm_free(va);
+}
+
+void vunmap(const void *va)
+{
+    enum vmap_region type = VMAP_DEFAULT;
+    unsigned int pages = vm_size(va, type);
+
+    if ( !pages )
+    {
+        type = VMAP_XEN;
+        pages = vm_size(va, type);
+    }
+    vunmap_pages(va, pages);
+}
+
 void *__vmap(const mfn_t *mfn, unsigned int granularity,
-             unsigned int nr, unsigned int align, unsigned int flags)
+             unsigned int nr, unsigned int align, unsigned int flags,
+             enum vmap_region type)
 {
-    void *va = vm_alloc(nr * granularity, align);
+    void *va = vm_alloc(nr * granularity, align, type);
     unsigned long cur = (unsigned long)va;
 
     for ( ; va && nr--; ++mfn, cur += PAGE_SIZE * granularity )
     {
         if ( map_pages_to_xen(cur, mfn_x(*mfn), granularity, flags) )
         {
-            vunmap(va);
+            vunmap_pages(va, vm_size(va, type));
             va = NULL;
         }
     }
@@ -201,22 +245,10 @@ void *__vmap(const mfn_t *mfn, unsigned int granularity,
 
 void *vmap(const mfn_t *mfn, unsigned int nr)
 {
-    return __vmap(mfn, 1, nr, 1, PAGE_HYPERVISOR);
-}
-
-void vunmap(const void *va)
-{
-#ifndef _PAGE_NONE
-    unsigned long addr = (unsigned long)va;
-
-    destroy_xen_mappings(addr, addr + PAGE_SIZE * vm_size(va));
-#else /* Avoid tearing down intermediate page tables. */
-    map_pages_to_xen((unsigned long)va, 0, vm_size(va), _PAGE_NONE);
-#endif
-    vm_free(va);
+    return __vmap(mfn, 1, nr, 1, PAGE_HYPERVISOR, VMAP_DEFAULT);
 }
 
-void *vmalloc(size_t size)
+static void *vmalloc_type(size_t size, enum vmap_region type)
 {
     mfn_t *mfn;
     size_t pages, i;
@@ -238,7 +270,7 @@ void *vmalloc(size_t size)
         mfn[i] = _mfn(page_to_mfn(pg));
     }
 
-    va = vmap(mfn, pages);
+    va = __vmap(mfn, 1, pages, 1, PAGE_HYPERVISOR, type);
     if ( va == NULL )
         goto error;
 
@@ -252,9 +284,19 @@ void *vmalloc(size_t size)
     return NULL;
 }
 
-void *vzalloc(size_t size)
+void *vmalloc(size_t size)
 {
-    void *p = vmalloc(size);
+    return vmalloc_type(size, VMAP_DEFAULT);
+}
+
+void *vmalloc_xen(size_t size)
+{
+    return vmalloc_type(size, VMAP_XEN);
+}
+
+static void *vzalloc_type(size_t size, enum vmap_region type)
+{
+    void *p = vmalloc_type(size, type);
     int i;
 
     if ( p == NULL )
@@ -266,16 +308,32 @@ void *vzalloc(size_t size)
     return p;
 }
 
+void *vzalloc(size_t size)
+{
+    return vzalloc_type(size, VMAP_DEFAULT);
+}
+
+void *vzalloc_xen(size_t size)
+{
+    return vzalloc_type(size, VMAP_XEN);
+}
+
 void vfree(void *va)
 {
     unsigned int i, pages;
     struct page_info *pg;
     PAGE_LIST_HEAD(pg_list);
+    enum vmap_region type = VMAP_DEFAULT;
 
     if ( !va )
         return;
 
-    pages = vm_size(va);
+    pages = vm_size(va, type);
+    if ( !pages )
+    {
+        type = VMAP_XEN;
+        pages = vm_size(va, type);
+    }
     ASSERT(pages);
 
     for ( i = 0; i < pages; i++ )
@@ -285,7 +343,7 @@ void vfree(void *va)
         ASSERT(page);
         page_list_add(page, &pg_list);
     }
-    vunmap(va);
+    vunmap_pages(va, pages);
 
     while ( (pg = page_list_remove_head(&pg_list)) != NULL )
         free_domheap_page(pg);
diff --git a/xen/drivers/acpi/osl.c b/xen/drivers/acpi/osl.c
index 8a28d87..9a49029 100644
--- a/xen/drivers/acpi/osl.c
+++ b/xen/drivers/acpi/osl.c
@@ -97,7 +97,7 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 		if (IS_ENABLED(CONFIG_X86) && !((phys + size - 1) >> 20))
 			return __va(phys);
 		return __vmap(&mfn, PFN_UP(offs + size), 1, 1,
-			      ACPI_MAP_MEM_ATTR) + offs;
+			      ACPI_MAP_MEM_ATTR, VMAP_DEFAULT) + offs;
 	}
 	return __acpi_map_table(phys, size);
 }
diff --git a/xen/include/xen/vmap.h b/xen/include/xen/vmap.h
index 5671ac8..3434b6e 100644
--- a/xen/include/xen/vmap.h
+++ b/xen/include/xen/vmap.h
@@ -4,15 +4,24 @@
 #include <xen/mm.h>
 #include <asm/page.h>
 
-void *vm_alloc(unsigned int nr, unsigned int align);
-void vm_free(const void *);
+enum vmap_region {
+    VMAP_DEFAULT,
+    VMAP_XEN,
+    VMAP_REGION_NR,
+};
 
-void *__vmap(const mfn_t *mfn, unsigned int granularity,
-             unsigned int nr, unsigned int align, unsigned int flags);
+void vm_init_type(enum vmap_region type, void *start, void *end);
+
+void *__vmap(const mfn_t *mfn, unsigned int granularity, unsigned int nr,
+             unsigned int align, unsigned int flags, enum vmap_region);
 void *vmap(const mfn_t *mfn, unsigned int nr);
 void vunmap(const void *);
+
 void *vmalloc(size_t size);
+void *vmalloc_xen(size_t size);
+
 void *vzalloc(size_t size);
+void *vzalloc_xen(size_t size);
 void vfree(void *va);
 
 void __iomem *ioremap(paddr_t, size_t);
@@ -24,7 +33,10 @@ static inline void iounmap(void __iomem *va)
     vunmap((void *)(addr & PAGE_MASK));
 }
 
-void vm_init(void);
 void *arch_vmap_virt_end(void);
+static inline void vm_init(void)
+{
+    vm_init_type(VMAP_DEFAULT, (void *)VMAP_VIRT_START, arch_vmap_virt_end());
+}
 
 #endif /* __XEN_VMAP_H__ */
-- 
2.4.3


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