[PATCH v3 bpf-next 2/3] mm, xen: Separate xen use cases from ioremap.

[Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>]

From: Alexei Starovoitov <ast@xxxxxxxxxx>

xen grant table and xenbus ring are not ioremap the way arch specific code
is using it, so let's add VM_XEN flag to separate these use cases from
VM_IOREMAP users. xen will not and should not be calling
ioremap_page_range() on that range. /proc/vmallocinfo will print such
regions as "xen" instead of "ioremap".

Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
 arch/x86/xen/grant-table.c         | 2 +-
 drivers/xen/xenbus/xenbus_client.c | 2 +-
 include/linux/vmalloc.h            | 1 +
 mm/vmalloc.c                       | 7 +++++--
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/xen/grant-table.c b/arch/x86/xen/grant-table.c
index 1e681bf62561..b816db0349c4 100644
--- a/arch/x86/xen/grant-table.c
+++ b/arch/x86/xen/grant-table.c
@@ -104,7 +104,7 @@ static int arch_gnttab_valloc(struct gnttab_vm_area *area, 
unsigned nr_frames)
        area->ptes = kmalloc_array(nr_frames, sizeof(*area->ptes), GFP_KERNEL);
        if (area->ptes == NULL)
                return -ENOMEM;
-       area->area = get_vm_area(PAGE_SIZE * nr_frames, VM_IOREMAP);
+       area->area = get_vm_area(PAGE_SIZE * nr_frames, VM_XEN);
        if (!area->area)
                goto out_free_ptes;
        if (apply_to_page_range(&init_mm, (unsigned long)area->area->addr,
diff --git a/drivers/xen/xenbus/xenbus_client.c 
b/drivers/xen/xenbus/xenbus_client.c
index 32835b4b9bc5..b9c81a2d578b 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -758,7 +758,7 @@ static int xenbus_map_ring_pv(struct xenbus_device *dev,
        bool leaked = false;
        int err = -ENOMEM;
 
-       area = get_vm_area(XEN_PAGE_SIZE * nr_grefs, VM_IOREMAP);
+       area = get_vm_area(XEN_PAGE_SIZE * nr_grefs, VM_XEN);
        if (!area)
                return -ENOMEM;
        if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index c720be70c8dd..71075ece0ed2 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -28,6 +28,7 @@ struct iov_iter;              /* in uio.h */
 #define VM_FLUSH_RESET_PERMS   0x00000100      /* reset direct map and flush 
TLB on unmap, can't be freed in atomic context */
 #define VM_MAP_PUT_PAGES       0x00000200      /* put pages and free array in 
vfree */
 #define VM_ALLOW_HUGE_VMAP     0x00000400      /* Allow for huge pages on 
archs with HAVE_ARCH_HUGE_VMALLOC */
+#define VM_XEN                 0x00000800      /* xen grant table and xenbus 
use cases */
 
 #if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
        !defined(CONFIG_KASAN_VMALLOC)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f42f98a127d5..d53ece3f38ee 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3822,9 +3822,9 @@ long vread_iter(struct iov_iter *iter, const char *addr, 
size_t count)
 
                if (flags & VMAP_RAM)
                        copied = vmap_ram_vread_iter(iter, addr, n, flags);
-               else if (!(vm && (vm->flags & VM_IOREMAP)))
+               else if (!(vm && (vm->flags & (VM_IOREMAP | VM_XEN))))
                        copied = aligned_vread_iter(iter, addr, n);
-               else /* IOREMAP area is treated as memory hole */
+               else /* IOREMAP | XEN area is treated as memory hole */
                        copied = zero_iter(iter, n);
 
                addr += copied;
@@ -4415,6 +4415,9 @@ static int s_show(struct seq_file *m, void *p)
        if (v->flags & VM_IOREMAP)
                seq_puts(m, " ioremap");
 
+       if (v->flags & VM_XEN)
+               seq_puts(m, " xen");
+
        if (v->flags & VM_ALLOC)
                seq_puts(m, " vmalloc");
 
-- 
2.34.1