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.comSigned-off-by: Juergen Gross <jgross@suse.com>

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)

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;

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;

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;
 		}

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);