[PATCH v10 02/12] arch/arm: unmap partially-mapped I/O-memory regions

[Arianna Avanzini <avanzini.arianna@gmail.com>]

This commit changes the function apply_p2m_changes() to destroy changes
performed while mapping an I/O-memory region, if errors are seen during
the operation. The implemented behaviour is the counterpart of the x86
code, which destroys the whole range: this is useful to avoid that I/O-
memory areas are partially accessible to guests.

Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Cc: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Paolo Valente <paolo.valente@unimore.it>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Julien Grall <julien.grall@citrix.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Tim Deegan <tim@xen.org>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Eric Trudeau <etrudeau@broadcom.com>
Cc: Viktor Kleinik <viktor.kleinik@globallogic.com>

---

    v10:
        - Recursively call apply_p2m_changes() on the whole I/O-memory range
          when unmapping a partially-mapped I/O-memory region.

    v9:
        - Let apply_p2m_ranges() unwind its own progress instead of relying on
          the caller to unmap partially-mapped I/O-memory regions.
        - Adapt to rework of p2m-related functions for ARM.

---
 xen/arch/arm/p2m.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 8feb5c5..2745279 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -713,7 +713,7 @@ static int apply_p2m_changes(struct domain *d,
     int rc, ret;
     struct p2m_domain *p2m = &d->arch.p2m;
     lpae_t *first = NULL, *second = NULL, *third = NULL;
-    paddr_t addr;
+    paddr_t addr, orig_maddr = maddr;
     unsigned long cur_first_page = ~0,
                   cur_first_offset = ~0,
                   cur_second_offset = ~0;
@@ -844,6 +844,10 @@ out:
     if (third) unmap_domain_page(third);
     if (second) unmap_domain_page(second);
     if (first) unmap_domain_page(first);
+    if ( rc < 0 && mattr == MATTR_DEV && ( op == INSERT || op == ALLOCATE ) )
+        apply_p2m_changes(d, REMOVE, start_gpaddr,
+                          end_gpaddr, orig_maddr,
+                          MATTR_DEV, p2m_invalid);
 
     spin_unlock(&p2m->lock);
 
-- 
2.0.3