[PATCH v8 05/14] arch/arm: unmap partially-mapped I/O-memory regions

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

This commit changes the interface of apply_p2m_changes() to accept
optionally the pointer to a counter of successfully performed
mappings; such a counter is used only in case of INSERT operation.
If an error is encountered during the operation, and therefore the
mapping is only partially performed, such a counter is useful to
let the caller be able to undo what has just been done.

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>

---

    v8:
        - Use correct count in unmap_mmio_regions().

    v6:
        - Pass p2m_invalid as last parameter to unmap_mmio_regions() for ARM
          as it is not (and currently must not be) used.

---
 xen/arch/arm/p2m.c        | 42 +++++++++++++++++++++++++++++++++---------
 xen/include/asm-arm/p2m.h |  4 ++++
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 2d8b78f..cf01736 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -294,6 +294,7 @@ static int apply_p2m_changes(struct domain *d,
                      paddr_t start_gpaddr,
                      paddr_t end_gpaddr,
                      paddr_t maddr,
+                     unsigned long *nr_inserted,
                      int mattr,
                      p2m_type_t t)
 {
@@ -304,7 +305,7 @@ static int apply_p2m_changes(struct domain *d,
     unsigned long cur_first_page = ~0,
                   cur_first_offset = ~0,
                   cur_second_offset = ~0;
-    unsigned long count = 0;
+    unsigned long count = 0, inserted = 0;
     unsigned int flush = 0;
     bool_t populate = (op == INSERT || op == ALLOCATE);
     lpae_t pte;
@@ -420,6 +421,7 @@ static int apply_p2m_changes(struct domain *d,
                 {
                     pte = mfn_to_p2m_entry(maddr >> PAGE_SHIFT, mattr, t);
                     write_pte(&third[third_table_offset(addr)], pte);
+                    inserted++;
                 }
                 break;
             case REMOVE:
@@ -519,6 +521,8 @@ out:
     if (second) unmap_domain_page(second);
     if (first) unmap_domain_page(first);
 
+    if ( nr_inserted != NULL ) *nr_inserted = inserted;
+
     spin_unlock(&p2m->lock);
 
     return rc;
@@ -529,7 +533,7 @@ int p2m_populate_ram(struct domain *d,
                      paddr_t end)
 {
     return apply_p2m_changes(d, ALLOCATE, start, end,
-                             0, MATTR_MEM, p2m_ram_rw);
+                             0, NULL, MATTR_MEM, p2m_ram_rw);
 }
 
 int map_mmio_regions(struct domain *d,
@@ -537,11 +541,31 @@ int map_mmio_regions(struct domain *d,
                      unsigned long nr_mfns,
                      unsigned long mfn)
 {
-    return apply_p2m_changes(d, INSERT,
+    unsigned long nr_inserted;
+    int ret;
+
+    ret = apply_p2m_changes(d, INSERT,
+                            pfn_to_paddr(start_gfn),
+                            pfn_to_paddr(start_gfn + nr_mfns),
+                            pfn_to_paddr(mfn),
+                            &nr_inserted,
+                            MATTR_DEV, p2m_mmio_direct);
+    if ( ret && nr_inserted != 0 )
+        unmap_mmio_regions(d, start_gfn, nr_inserted, mfn);
+
+    return ret;
+}
+
+int unmap_mmio_regions(struct domain *d,
+                       unsigned long start_gfn,
+                       unsigned long nr_mfns,
+                       unsigned long mfn)
+{
+    return apply_p2m_changes(d, REMOVE,
                              pfn_to_paddr(start_gfn),
                              pfn_to_paddr(start_gfn + nr_mfns),
-                             pfn_to_paddr(mfn),
-                             MATTR_DEV, p2m_mmio_direct);
+                             pfn_to_paddr(mfn), NULL,
+                             MATTR_DEV, p2m_invalid);
 }
 
 int guest_physmap_add_entry(struct domain *d,
@@ -553,7 +577,7 @@ int guest_physmap_add_entry(struct domain *d,
     return apply_p2m_changes(d, INSERT,
                              pfn_to_paddr(gpfn),
                              pfn_to_paddr(gpfn + (1 << page_order)),
-                             pfn_to_paddr(mfn), MATTR_MEM, t);
+                             pfn_to_paddr(mfn), NULL, MATTR_MEM, t);
 }
 
 void guest_physmap_remove_page(struct domain *d,
@@ -563,7 +587,7 @@ void guest_physmap_remove_page(struct domain *d,
     apply_p2m_changes(d, REMOVE,
                       pfn_to_paddr(gpfn),
                       pfn_to_paddr(gpfn + (1<<page_order)),
-                      pfn_to_paddr(mfn), MATTR_MEM, p2m_invalid);
+                      pfn_to_paddr(mfn), NULL, MATTR_MEM, p2m_invalid);
 }
 
 int p2m_alloc_table(struct domain *d)
@@ -710,7 +734,7 @@ int relinquish_p2m_mapping(struct domain *d)
     return apply_p2m_changes(d, RELINQUISH,
                               pfn_to_paddr(p2m->lowest_mapped_gfn),
                               pfn_to_paddr(p2m->max_mapped_gfn),
-                              pfn_to_paddr(INVALID_MFN),
+                              pfn_to_paddr(INVALID_MFN), NULL,
                               MATTR_MEM, p2m_invalid);
 }
 
@@ -725,7 +749,7 @@ int p2m_cache_flush(struct domain *d, xen_pfn_t start_mfn, xen_pfn_t end_mfn)
                              pfn_to_paddr(start_mfn),
                              pfn_to_paddr(end_mfn),
                              pfn_to_paddr(INVALID_MFN),
-                             MATTR_MEM, p2m_invalid);
+                             NULL, MATTR_MEM, p2m_invalid);
 }
 
 unsigned long gmfn_to_mfn(struct domain *d, unsigned long gpfn)
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 6d56daa..71665f3 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -91,6 +91,10 @@ int map_mmio_regions(struct domain *d,
                      unsigned long start_gfn,
                      unsigned long nr_mfns,
                      unsigned long mfn);
+int unmap_mmio_regions(struct domain *d,
+                       unsigned long start_gfn,
+                       unsigned long nr_mfns,
+                       unsigned long mfn);
 
 int guest_physmap_add_entry(struct domain *d,
                             unsigned long gfn,
-- 
1.9.2