xen/arm: mm: Change the return value of gvirt_to_maddr

Currently, gvirt_to_maddr return -EFAULT when the translation failed.
It might be useful to return the PAR_EL1 (Physical Address Register)
in such a case to get a better idea of the reason.

So modify the return value to use 0 on success or return the PAR on
failure.

The callers are modified to reflect the change of the return value.

Note that with the change in gvirt_to_maddr, ma needs to be initialized
to avoid GCC been confused (i.e value may be uninitialized) with the new
construction.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/domain_build.c

@@ -2002,15 +2002,15 @@ static void initrd_load(struct kernel_info *kinfo)
 
     for ( offs = 0; offs < len; )
     {
-        int rc;
-        paddr_t s, l, ma;
+        uint64_t par;
+        paddr_t s, l, ma = 0;
         void *dst;
 
         s = offs & ~PAGE_MASK;
         l = min(PAGE_SIZE - s, len);
 
-        rc = gvirt_to_maddr(load_addr + offs, &ma, GV2M_WRITE);
-        if ( rc )
+        par = gvirt_to_maddr(load_addr + offs, &ma, GV2M_WRITE);
+        if ( par )
         {
             panic("Unable to translate guest address");
             return;

xen/arch/arm/kernel.c

@@ -167,15 +167,15 @@ static void kernel_zimage_load(struct kernel_info *info)
            paddr, load_addr, load_addr + len);
     for ( offs = 0; offs < len; )
     {
-        int rc;
-        paddr_t s, l, ma;
+        uint64_t par;
+        paddr_t s, l, ma = 0;
         void *dst;
 
         s = offs & ~PAGE_MASK;
         l = min(PAGE_SIZE - s, len);
 
-        rc = gvirt_to_maddr(load_addr + offs, &ma, GV2M_WRITE);
-        if ( rc )
+        par = gvirt_to_maddr(load_addr + offs, &ma, GV2M_WRITE);
+        if ( par )
         {
             panic("Unable to map translate guest address");
             return;

xen/arch/arm/p2m.c

@@ -1414,7 +1414,7 @@ struct page_info *get_page_from_gva(struct vcpu *v, vaddr_t va,
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
     struct page_info *page = NULL;
     paddr_t maddr = 0;
-    int rc;
+    uint64_t par;
 
     /*
      * XXX: To support a different vCPU, we would need to load the
@@ -1425,9 +1425,9 @@ struct page_info *get_page_from_gva(struct vcpu *v, vaddr_t va,
 
     p2m_read_lock(p2m);
 
-    rc = gvirt_to_maddr(va, &maddr, flags);
+    par = gvirt_to_maddr(va, &maddr, flags);
 
-    if ( rc )
+    if ( par )
         goto err;
 
     if ( !mfn_valid(maddr_to_mfn(maddr)) )

xen/include/asm-arm/mm.h

@@ -266,11 +266,16 @@ static inline void *maddr_to_virt(paddr_t ma)
 }
 #endif
 
-static inline int gvirt_to_maddr(vaddr_t va, paddr_t *pa, unsigned int flags)
+/*
+ * Translate a guest virtual address to a machine address.
+ * Return the fault information if the translation has failed else 0.
+ */
+static inline uint64_t gvirt_to_maddr(vaddr_t va, paddr_t *pa,
+                                      unsigned int flags)
 {
     uint64_t par = gva_to_ma_par(va, flags);
     if ( par & PAR_F )
-        return -EFAULT;
+        return par;
     *pa = (par & PADDR_MASK & PAGE_MASK) | ((unsigned long) va & ~PAGE_MASK);
     return 0;
 }