xen: replace xen_remap() with memremap()

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@intel.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20220530082634.6339-1-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>

1 files changed, 1 insertions, 1 deletions

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;