[PATCH] xen: replace xen_remap() with memremap()

[Juergen Gross <jgross@xxxxxxxx>]

xen_remap() is used to establish mappings for frames not under direct
control of the kernel: for Xenstore and console ring pages, and for
grant pages of non-PV guests.

Today xen_remap() is defined to use ioremap() on x86 (doing uncached
mappings), and ioremap_cache() on Arm (doing cached mappings).

Uncached mappings for those use cases are bad for performance, so they
should be avoided if possible. As all use cases of xen_remap() don't
require uncached mappings (the mapped area is always physical RAM),
a mapping using the standard WB cache mode is fine.

As sparse is flagging some of the xen_remap() use cases to be not
appropriate for iomem(), as the result is not annotated with the
__iomem modifier, eliminate xen_remap() completely and replace all
use cases with memremap() specifying the MEMREMAP_WB caching mode.

xen_unmap() can be replaced with memunmap().

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 arch/x86/include/asm/xen/page.h   | 3 ---
 drivers/tty/hvc/hvc_xen.c         | 2 +-
 drivers/xen/grant-table.c         | 6 +++---
 drivers/xen/xenbus/xenbus_probe.c | 8 ++++----
 include/xen/arm/page.h            | 3 ---
 5 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 1fc67df50014..fa9ec20783fa 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -347,9 +347,6 @@ unsigned long arbitrary_virt_to_mfn(void *vaddr);
 void make_lowmem_page_readonly(void *vaddr);
 void make_lowmem_page_readwrite(void *vaddr);
 
-#define xen_remap(cookie, size) ioremap((cookie), (size))
-#define xen_unmap(cookie) iounmap((cookie))
-
 static inline bool xen_arch_need_swiotlb(struct device *dev,
                                         phys_addr_t phys,
                                         dma_addr_t dev_addr)
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index ebaf7500f48f..7c23112dc923 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -253,7 +253,7 @@ static int xen_hvm_console_init(void)
        if (r < 0 || v == 0)
                goto err;
        gfn = v;
-       info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE);
+       info->intf = memremap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, 
MEMREMAP_WB);
        if (info->intf == NULL)
                goto err;
        info->vtermno = HVC_COOKIE;
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 1a1aec0a88a1..2f4f0ed5d8f8 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -632,7 +632,7 @@ int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
        if (xen_auto_xlat_grant_frames.count)
                return -EINVAL;
 
-       vaddr = xen_remap(addr, XEN_PAGE_SIZE * max_nr_gframes);
+       vaddr = memremap(addr, XEN_PAGE_SIZE * max_nr_gframes, MEMREMAP_WB);
        if (vaddr == NULL) {
                pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
                        &addr);
@@ -640,7 +640,7 @@ int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
        }
        pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
        if (!pfn) {
-               xen_unmap(vaddr);
+               memunmap(vaddr);
                return -ENOMEM;
        }
        for (i = 0; i < max_nr_gframes; i++)
@@ -659,7 +659,7 @@ void gnttab_free_auto_xlat_frames(void)
        if (!xen_auto_xlat_grant_frames.count)
                return;
        kfree(xen_auto_xlat_grant_frames.pfn);
-       xen_unmap(xen_auto_xlat_grant_frames.vaddr);
+       memunmap(xen_auto_xlat_grant_frames.vaddr);
 
        xen_auto_xlat_grant_frames.pfn = NULL;
        xen_auto_xlat_grant_frames.count = 0;
diff --git a/drivers/xen/xenbus/xenbus_probe.c 
b/drivers/xen/xenbus/xenbus_probe.c
index d367f2bd2b93..58b732dcbfb8 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -752,8 +752,8 @@ static void xenbus_probe(void)
        xenstored_ready = 1;
 
        if (!xen_store_interface) {
-               xen_store_interface = xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
-                                               XEN_PAGE_SIZE);
+               xen_store_interface = memremap(xen_store_gfn << XEN_PAGE_SHIFT,
+                                              XEN_PAGE_SIZE, MEMREMAP_WB);
                /*
                 * Now it is safe to free the IRQ used for xenstore late
                 * initialization. No need to unbind: it is about to be
@@ -1009,8 +1009,8 @@ static int __init xenbus_init(void)
 #endif
                        xen_store_gfn = (unsigned long)v;
                        xen_store_interface =
-                               xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
-                                         XEN_PAGE_SIZE);
+                               memremap(xen_store_gfn << XEN_PAGE_SHIFT,
+                                        XEN_PAGE_SIZE, MEMREMAP_WB);
                        if (xen_store_interface->connection != 
XENSTORE_CONNECTED)
                                wait = true;
                }
diff --git a/include/xen/arm/page.h b/include/xen/arm/page.h
index 7e199c6656b9..e5c84ff28c8b 100644
--- a/include/xen/arm/page.h
+++ b/include/xen/arm/page.h
@@ -109,9 +109,6 @@ static inline bool set_phys_to_machine(unsigned long pfn, 
unsigned long mfn)
        return __set_phys_to_machine(pfn, mfn);
 }
 
-#define xen_remap(cookie, size) ioremap_cache((cookie), (size))
-#define xen_unmap(cookie) iounmap((cookie))
-
 bool xen_arch_need_swiotlb(struct device *dev,
                           phys_addr_t phys,
                           dma_addr_t dev_addr);
-- 
2.35.3