From: Grygorii Strashko <gragst.linux@gmail.com>
Date: Tue, 18 Feb 2025 11:22:52 +0000 (+0200)
Subject: xen/arm: fix iomem permissions cfg in map_range_to_domain()
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=9568ceb2877dae593dbac29a1154f63bdea65c20;p=people%2Froyger%2Fxen.git

xen/arm: fix iomem permissions cfg in map_range_to_domain()

Now the following code in map_range_to_domain()

    res = iomem_permit_access(d, paddr_to_pfn(addr),
                    paddr_to_pfn(PAGE_ALIGN(addr + len - 1)));

calculates the iomem range end address by rounding it up to the next Xen
page with incorrect assumption that iomem range end address passed to
iomem_permit_access() is exclusive, while it is expected to be inclusive.
It gives Control domain (Dom0) access to manage incorrect MMIO range with
one additional page.

For example, if requested range is [00e6140000:00e6141004] then it expected
to add [e6140:e6141] range (num_pages=2) to the domain iomem_caps rangeset,
but will add [e6140:e6142] (num_pages=3) instead.

To fix it, drop PAGE_ALIGN() from the iomem range end address calculation
formula.

Fixes: 33233c2758345 ("arch/arm: domain build: let dom0 access I/O memory of mapped devices")
Signed-off-by: Grygorii Strashko <grygorii_strashko@epam.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
---

diff --git a/xen/arch/arm/device.c b/xen/arch/arm/device.c
index 5610cddcba..97e613e06a 100644
--- a/xen/arch/arm/device.c
+++ b/xen/arch/arm/device.c
@@ -71,7 +71,7 @@ int map_range_to_domain(const struct dt_device_node *dev,
                      strlen("/reserved-memory/")) != 0 )
     {
         res = iomem_permit_access(d, paddr_to_pfn(addr),
-                paddr_to_pfn(PAGE_ALIGN(addr + len - 1)));
+                                  paddr_to_pfn(addr + len - 1));
         if ( res )
         {
             printk(XENLOG_ERR "Unable to permit to dom%d access to"