[Xen-changelog] [xen master] arch/x86: warn if to-be-removed mapping does not exist

[patchbot@xxxxxxx]

commit 28b5f84209dfef73efeaff23871cd081c383c6b4
Author:     Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
AuthorDate: Sat Aug 30 18:29:38 2014 +0200
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Wed Sep 3 12:49:37 2014 +0100

    arch/x86: warn if to-be-removed mapping does not exist
    
    Currently, when a memory mapping is removed with the memory_mapping
    DOMCTL, no check is performed on the existence of such a mapping.
    This commit adds such a consistency check to the code performing the
    unmap, emitting a warning message if the check fails.
    
    Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Cc: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
    Cc: Paolo Valente <paolo.valente@xxxxxxxxxx>
    Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
    Cc: Julien Grall <julien.grall@xxxxxxxxxx>
    Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
    Cc: Keir Fraser <keir@xxxxxxx>
    Cc: Tim Deegan <tim@xxxxxxx>
    Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
    Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Cc: Eric Trudeau <etrudeau@xxxxxxxxxxxx>
    Cc: Viktor Kleinik <viktor.kleinik@xxxxxxxxxxxxxxx>
    Cc: Andrii Tseglytskyi <andrii.tseglytskyi@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/domctl.c     |    4 ++--
 xen/arch/x86/mm/p2m.c     |   12 ++++++++----
 xen/common/memory.c       |    2 +-
 xen/include/asm-x86/p2m.h |    2 +-
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index d1517c4..1ead690 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -679,7 +679,7 @@ long arch_do_domctl(
                            "memory_map:fail: dom%d gfn=%lx mfn=%lx ret:%ld\n",
                            d->domain_id, gfn + i, mfn + i, ret);
                     while ( i-- )
-                        clear_mmio_p2m_entry(d, gfn + i);
+                        clear_mmio_p2m_entry(d, gfn + i, _mfn(mfn + i));
                     if ( iomem_deny_access(d, mfn, mfn + nr_mfns - 1) &&
                          is_hardware_domain(current->domain) )
                         printk(XENLOG_ERR
@@ -699,7 +699,7 @@ long arch_do_domctl(
             if ( paging_mode_translate(d) )
                 for ( i = 0; i < nr_mfns; i++ )
                 {
-                    ret = clear_mmio_p2m_entry(d, gfn + i);
+                    ret = clear_mmio_p2m_entry(d, gfn + i, _mfn(mfn + i));
                     if ( ret )
                         tmp_rc = ret;
                 }
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index c2e89e1..2586a3c 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -859,10 +859,10 @@ int set_mmio_p2m_entry(struct domain *d, unsigned long 
gfn, mfn_t mfn)
 }
 
 /* Returns: 0 for success, -errno for failure */
-int clear_mmio_p2m_entry(struct domain *d, unsigned long gfn)
+int clear_mmio_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn)
 {
     int rc = -EINVAL;
-    mfn_t mfn;
+    mfn_t actual_mfn;
     p2m_access_t a;
     p2m_type_t t;
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
@@ -871,15 +871,19 @@ int clear_mmio_p2m_entry(struct domain *d, unsigned long 
gfn)
         return -EIO;
 
     gfn_lock(p2m, gfn, 0);
-    mfn = p2m->get_entry(p2m, gfn, &t, &a, 0, NULL);
+    actual_mfn = p2m->get_entry(p2m, gfn, &t, &a, 0, NULL);
 
     /* Do not use mfn_valid() here as it will usually fail for MMIO pages. */
-    if ( (INVALID_MFN == mfn_x(mfn)) || (t != p2m_mmio_direct) )
+    if ( (INVALID_MFN == mfn_x(actual_mfn)) || (t != p2m_mmio_direct) )
     {
         gdprintk(XENLOG_ERR,
                  "gfn_to_mfn failed! gfn=%08lx type:%d\n", gfn, t);
         goto out;
     }
+    if ( mfn_x(mfn) != mfn_x(actual_mfn) )
+        gdprintk(XENLOG_WARNING,
+                 "no mapping between mfn %08lx and gfn %08lx\n",
+                 mfn_x(mfn), gfn);
     rc = p2m_set_entry(p2m, gfn, _mfn(INVALID_MFN), PAGE_ORDER_4K, p2m_invalid,
                        p2m->default_access);
 
diff --git a/xen/common/memory.c b/xen/common/memory.c
index c2dd31b..2433111 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -206,7 +206,7 @@ int guest_remove_page(struct domain *d, unsigned long gmfn)
     }
     if ( p2mt == p2m_mmio_direct )
     {
-        clear_mmio_p2m_entry(d, gmfn);
+        clear_mmio_p2m_entry(d, gmfn, _mfn(mfn));
         put_gfn(d, gmfn);
         return 1;
     }
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 3975e32..d19f50c 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -534,7 +534,7 @@ int p2m_is_logdirty_range(struct p2m_domain *, unsigned 
long start,
 
 /* Set mmio addresses in the p2m table (for pass-through) */
 int set_mmio_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn);
-int clear_mmio_p2m_entry(struct domain *d, unsigned long gfn);
+int clear_mmio_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn);
 
 /* Add foreign mapping to the guest's p2m table. */
 int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
--
generated by git-patchbot for /home/xen/git/xen.git#master

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