[PATCH 5.15.y] xen: replace xen_remap() with memremap()

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

From: Juergen Gross <jgross@xxxxxxxx>

[ upstream commit 41925b105e345ebc84cedb64f59d20cb14a62613 ]

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>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220530082634.6339-1-jgross@xxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx> [backport to 5.15.y]
---
 arch/x86/include/asm/xen/page.h   | 3 ---
 drivers/xen/grant-table.c         | 6 +++---
 drivers/xen/xenbus/xenbus_probe.c | 3 +--
 3 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 1a162e559753..c183b7f9efef 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -355,9 +355,6 @@ 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/xen/grant-table.c b/drivers/xen/grant-table.c
index 0a2d24d6ac6f..a10e0741bec5 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -743,7 +743,7 @@ 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);
@@ -751,7 +751,7 @@ 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++)
@@ -770,7 +770,7 @@ 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 2068f83556b7..77ca24611293 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -982,8 +982,7 @@ 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);
                break;
        default:
                pr_warn("Xenstore state unknown\n");
-- 
2.50.0



Teddy Astie | Vates XCP-ng Developer

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