[PATCH 14/15] xen/arm: guest_walk_tables: Switch the return to bool

[Julien Grall <julien.grall@arm.com>]

At the moment, guest_walk_tables can either return 0, -EFAULT, -EINVAL.
The use of the last 2 are not clearly defined and used inconsistently in
the code. The current only caller does not care about the return
value and the value of it seems very limited (no way to differentiate
between the 15ish error paths).

So switch to bool to simplify the return and make the developper life a
bit easier.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
---
 xen/arch/arm/guest_walk.c        | 50 ++++++++++++++++++++--------------------
 xen/arch/arm/mem_access.c        |  2 +-
 xen/include/asm-arm/guest_walk.h |  8 +++----
 3 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/xen/arch/arm/guest_walk.c b/xen/arch/arm/guest_walk.c
index 4a1b4cf2c8..7db7a7321b 100644
--- a/xen/arch/arm/guest_walk.c
+++ b/xen/arch/arm/guest_walk.c
@@ -28,9 +28,9 @@
  * page table on a different vCPU, the following registers would need to be
  * loaded: TCR_EL1, TTBR0_EL1, TTBR1_EL1, and SCTLR_EL1.
  */
-static int guest_walk_sd(const struct vcpu *v,
-                         vaddr_t gva, paddr_t *ipa,
-                         unsigned int *perms)
+static bool guest_walk_sd(const struct vcpu *v,
+                          vaddr_t gva, paddr_t *ipa,
+                          unsigned int *perms)
 {
     int ret;
     bool disabled = true;
@@ -79,7 +79,7 @@ static int guest_walk_sd(const struct vcpu *v,
     }
 
     if ( disabled )
-        return -EFAULT;
+        return false;
 
     /*
      * The address of the L1 descriptor for the initial lookup has the
@@ -97,12 +97,12 @@ static int guest_walk_sd(const struct vcpu *v,
     /* Access the guest's memory to read only one PTE. */
     ret = access_guest_memory_by_ipa(d, paddr, &pte, sizeof(short_desc_t), false);
     if ( ret )
-        return -EINVAL;
+        return false;
 
     switch ( pte.walk.dt )
     {
     case L1DESC_INVALID:
-        return -EFAULT;
+        return false;
 
     case L1DESC_PAGE_TABLE:
         /*
@@ -122,10 +122,10 @@ static int guest_walk_sd(const struct vcpu *v,
         /* Access the guest's memory to read only one PTE. */
         ret = access_guest_memory_by_ipa(d, paddr, &pte, sizeof(short_desc_t), false);
         if ( ret )
-            return -EINVAL;
+            return false;
 
         if ( pte.walk.dt == L2DESC_INVALID )
-            return -EFAULT;
+            return false;
 
         if ( pte.pg.page ) /* Small page. */
         {
@@ -175,7 +175,7 @@ static int guest_walk_sd(const struct vcpu *v,
             *perms |= GV2M_EXEC;
     }
 
-    return 0;
+    return true;
 }
 
 /*
@@ -355,9 +355,9 @@ static bool check_base_size(unsigned int output_size, uint64_t base)
  * page table on a different vCPU, the following registers would need to be
  * loaded: TCR_EL1, TTBR0_EL1, TTBR1_EL1, and SCTLR_EL1.
  */
-static int guest_walk_ld(const struct vcpu *v,
-                         vaddr_t gva, paddr_t *ipa,
-                         unsigned int *perms)
+static bool guest_walk_ld(const struct vcpu *v,
+                          vaddr_t gva, paddr_t *ipa,
+                          unsigned int *perms)
 {
     int ret;
     bool disabled = true;
@@ -442,7 +442,7 @@ static int guest_walk_ld(const struct vcpu *v,
          */
         if ( (input_size > TCR_EL1_IPS_48_BIT_VAL) ||
              (input_size < TCR_EL1_IPS_MIN_VAL) )
-            return -EFAULT;
+            return false;
     }
     else
     {
@@ -487,7 +487,7 @@ static int guest_walk_ld(const struct vcpu *v,
     }
 
     if ( disabled )
-        return -EFAULT;
+        return false;
 
     /*
      * The starting level is the number of strides (grainsizes[gran] - 3)
@@ -498,12 +498,12 @@ static int guest_walk_ld(const struct vcpu *v,
     /* Get the IPA output_size. */
     ret = get_ipa_output_size(d, tcr, &output_size);
     if ( ret )
-        return -EFAULT;
+        return false;
 
     /* Make sure the base address does not exceed its configured size. */
     ret = check_base_size(output_size, ttbr);
     if ( !ret )
-        return -EFAULT;
+        return false;
 
     /*
      * Compute the base address of the first level translation table that is
@@ -523,12 +523,12 @@ static int guest_walk_ld(const struct vcpu *v,
         /* Access the guest's memory to read only one PTE. */
         ret = access_guest_memory_by_ipa(d, paddr, &pte, sizeof(lpae_t), false);
         if ( ret )
-            return -EFAULT;
+            return false;
 
         /* Make sure the base address does not exceed its configured size. */
         ret = check_base_size(output_size, pfn_to_paddr(pte.walk.base));
         if ( !ret )
-            return -EFAULT;
+            return false;
 
         /*
          * If page granularity is 64K, make sure the address is aligned
@@ -537,7 +537,7 @@ static int guest_walk_ld(const struct vcpu *v,
         if ( (output_size < TCR_EL1_IPS_52_BIT_VAL) &&
              (gran == GRANULE_SIZE_INDEX_64K) &&
              (pte.walk.base & 0xf) )
-            return -EFAULT;
+            return false;
 
         /*
          * Break if one of the following conditions is true:
@@ -567,7 +567,7 @@ static int guest_walk_ld(const struct vcpu *v,
      * maps a memory block at level 3 (PTE<1:0> == 01).
      */
     if ( !lpae_is_valid(pte) || !lpae_is_mapping(pte, level) )
-        return -EFAULT;
+        return false;
 
     /* Make sure that the lower bits of the PTE's base address are zero. */
     mask = GENMASK_ULL(47, grainsizes[gran]);
@@ -583,11 +583,11 @@ static int guest_walk_ld(const struct vcpu *v,
     if ( !pte.pt.xn && !xn_table )
         *perms |= GV2M_EXEC;
 
-    return 0;
+    return true;
 }
 
-int guest_walk_tables(const struct vcpu *v, vaddr_t gva,
-                      paddr_t *ipa, unsigned int *perms)
+bool guest_walk_tables(const struct vcpu *v, vaddr_t gva,
+                       paddr_t *ipa, unsigned int *perms)
 {
     uint32_t sctlr = READ_SYSREG(SCTLR_EL1);
     register_t tcr = READ_SYSREG(TCR_EL1);
@@ -595,7 +595,7 @@ int guest_walk_tables(const struct vcpu *v, vaddr_t gva,
 
     /* We assume that the domain is running on the currently active domain. */
     if ( v != current )
-        return -EFAULT;
+        return false;
 
     /* Allow perms to be NULL. */
     perms = perms ?: &_perms;
@@ -619,7 +619,7 @@ int guest_walk_tables(const struct vcpu *v, vaddr_t gva,
         /* Memory can be accessed without any restrictions. */
         *perms = GV2M_READ|GV2M_WRITE|GV2M_EXEC;
 
-        return 0;
+        return true;
     }
 
     if ( is_32bit_domain(v->domain) && !(tcr & TTBCR_EAE) )
diff --git a/xen/arch/arm/mem_access.c b/xen/arch/arm/mem_access.c
index ae2686ffa2..57ec7872bb 100644
--- a/xen/arch/arm/mem_access.c
+++ b/xen/arch/arm/mem_access.c
@@ -125,7 +125,7 @@ p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned long flag,
          * The software gva to ipa translation can still fail, e.g., if the gva
          * is not mapped.
          */
-        if ( guest_walk_tables(v, gva, &ipa, &perms) < 0 )
+        if ( !guest_walk_tables(v, gva, &ipa, &perms) )
             return NULL;
 
         /*
diff --git a/xen/include/asm-arm/guest_walk.h b/xen/include/asm-arm/guest_walk.h
index 4ed8476e08..8768ac9894 100644
--- a/xen/include/asm-arm/guest_walk.h
+++ b/xen/include/asm-arm/guest_walk.h
@@ -2,10 +2,10 @@
 #define _XEN_GUEST_WALK_H
 
 /* Walk the guest's page tables in software. */
-int guest_walk_tables(const struct vcpu *v,
-                      vaddr_t gva,
-                      paddr_t *ipa,
-                      unsigned int *perms);
+bool guest_walk_tables(const struct vcpu *v,
+                       vaddr_t gva,
+                       paddr_t *ipa,
+                       unsigned int *perms);
 
 #endif /* _XEN_GUEST_WALK_H */
 
-- 
2.11.0


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