[Xen-changelog] [xen master] hvm/vidirian: Avoid printing page_to_mfn(NULL) on error paths

[patchbot@xxxxxxx]

commit c56cdf93750fd978aebd69dc113f12cc770ff8e3
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Oct 9 12:11:48 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Oct 9 12:11:48 2013 +0200

    hvm/vidirian: Avoid printing page_to_mfn(NULL) on error paths
    
    While working in the viridian code, I noticed that 4cb6c4f4941
    
    "x86/hvm: Use get_page_from_gfn() instead of get_gfn()/put_gfn."
    
    introduced two error paths where page_to_mfn(NULL) would be formatted and
    presented as a bad MFN.  This provides junk in the warning rather than
    something useful.
    
    These two codepaths are fixed up to match their counterpart in
    wrmsr_hypervisor_regs()
    
    While auditing the other changes from 4cb6c4f4941, I noticed a small
    optimisation which could be made by changing the order of the validity 
checks
    to remove 6 NULL pointer checks.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
---
 xen/arch/x86/hvm/hvm.c      |   28 ++++++++++++----------------
 xen/arch/x86/hvm/viridian.c |    4 ++--
 2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index de81e45..6fcd95a 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2499,27 +2499,25 @@ static enum hvm_copy_result __hvm_copy(
 
         page = get_page_from_gfn(curr->domain, gfn, &p2mt, P2M_UNSHARE);
 
+        if ( !page )
+            return HVMCOPY_bad_gfn_to_mfn;
+
         if ( p2m_is_paging(p2mt) )
         {
-            if ( page )
-                put_page(page);
+            put_page(page);
             p2m_mem_paging_populate(curr->domain, gfn);
             return HVMCOPY_gfn_paged_out;
         }
         if ( p2m_is_shared(p2mt) )
         {
-            if ( page )
-                put_page(page);
+            put_page(page);
             return HVMCOPY_gfn_shared;
         }
         if ( p2m_is_grant(p2mt) )
         {
-            if ( page )
-                put_page(page);
+            put_page(page);
             return HVMCOPY_unhandleable;
         }
-        if ( !page )
-            return HVMCOPY_bad_gfn_to_mfn;
 
         p = (char *)__map_domain_page(page) + (addr & ~PAGE_MASK);
 
@@ -2597,27 +2595,25 @@ static enum hvm_copy_result __hvm_clear(paddr_t addr, 
int size)
 
         page = get_page_from_gfn(curr->domain, gfn, &p2mt, P2M_UNSHARE);
 
+        if ( !page )
+            return HVMCOPY_bad_gfn_to_mfn;
+
         if ( p2m_is_paging(p2mt) )
         {
-            if ( page )
-                put_page(page);
+            put_page(page);
             p2m_mem_paging_populate(curr->domain, gfn);
             return HVMCOPY_gfn_paged_out;
         }
         if ( p2m_is_shared(p2mt) )
         {
-            if ( page )
-                put_page(page);
+            put_page(page);
             return HVMCOPY_gfn_shared;
         }
         if ( p2m_is_grant(p2mt) )
         {
-            if ( page )
-                put_page(page);
+            put_page(page);
             return HVMCOPY_unhandleable;
         }
-        if ( !page )
-            return HVMCOPY_bad_gfn_to_mfn;
 
         p = (char *)__map_domain_page(page) + (addr & ~PAGE_MASK);
 
diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index d5462f2..a6721c3 100644
--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -157,7 +157,7 @@ static void enable_hypercall_page(struct domain *d)
         if ( page )
             put_page(page);
         gdprintk(XENLOG_WARNING, "Bad GMFN %lx (MFN %lx)\n", gmfn,
-                 page_to_mfn(page));
+                 page ? page_to_mfn(page) : INVALID_MFN);
         return;
     }
 
@@ -202,7 +202,7 @@ static void initialize_apic_assist(struct vcpu *v)
         if ( page )
             put_page(page);
         gdprintk(XENLOG_WARNING, "Bad GMFN %lx (MFN %lx)\n", gmfn,
-                 page_to_mfn(page));
+                 page ? page_to_mfn(page) : INVALID_MFN);
         return;
     }
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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