[PATCH 06/12] xen/arm: ffa: Fix RX/TX map layout and errors

[Bertrand Marquis <bertrand.marquis@xxxxxxx>]

FFA_RXTX_MAP builds a descriptor for the SPMC and the composite region
offsets must be 8-byte aligned. Xen currently uses a 12-byte header
size, which produces misaligned RX/TX offsets. Mapping failures also
return INVALID_PARAMETERS even when the failure is due to resource
exhaustion, which misreports the error condition.

Round the descriptor header size up to 8 bytes before placing the RX
region and derive the TX offset from the aligned RX offset. Return
FFA_RET_NO_MEMORY when the TX or RX buffer mapping fails before the
error paths unwind.

Functional impact: RXTX_MAP now returns NO_MEMORY on mapping failures
and the SPMC receives an aligned RX/TX descriptor layout.

Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
 xen/arch/arm/tee/ffa_rxtx.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/tee/ffa_rxtx.c b/xen/arch/arm/tee/ffa_rxtx.c
index 50758fb57cdf..eff95a7955d7 100644
--- a/xen/arch/arm/tee/ffa_rxtx.c
+++ b/xen/arch/arm/tee/ffa_rxtx.c
@@ -119,11 +119,17 @@ int32_t ffa_handle_rxtx_map(uint32_t fid, register_t 
tx_addr,
 
     tx = __map_domain_page_global(tx_pg);
     if ( !tx )
+    {
+        ret = FFA_RET_NO_MEMORY;
         goto err_put_rx_pg;
+    }
 
     rx = __map_domain_page_global(rx_pg);
     if ( !rx )
+    {
+        ret = FFA_RET_NO_MEMORY;
         goto err_unmap_tx;
+    }
 
     /*
      * Transmit the RX/TX buffer information to the SPM if acquire is supported
@@ -136,7 +142,8 @@ int32_t ffa_handle_rxtx_map(uint32_t fid, register_t 
tx_addr,
         struct ffa_mem_region *mem_reg;
 
         /* All must fit in our TX buffer */
-        BUILD_BUG_ON(sizeof(*rxtx_desc) + sizeof(*mem_reg) * 2 +
+        BUILD_BUG_ON(ROUNDUP(sizeof(*rxtx_desc), 8) +
+                     sizeof(*mem_reg) * 2 +
                      sizeof(struct ffa_address_range) * 2 >
                      FFA_MAX_RXTX_PAGE_COUNT * FFA_PAGE_SIZE);
 
@@ -153,8 +160,8 @@ int32_t ffa_handle_rxtx_map(uint32_t fid, register_t 
tx_addr,
          */
         rxtx_desc->sender_id = ffa_get_vm_id(d);
         rxtx_desc->reserved = 0;
-        rxtx_desc->rx_region_offs = sizeof(*rxtx_desc);
-        rxtx_desc->tx_region_offs = sizeof(*rxtx_desc) +
+        rxtx_desc->rx_region_offs = ROUNDUP(sizeof(*rxtx_desc), 8);
+        rxtx_desc->tx_region_offs = rxtx_desc->rx_region_offs +
                                     offsetof(struct ffa_mem_region,
                                              address_range_array[1]);
 
-- 
2.50.1 (Apple Git-155)