[xen staging] arm: optee: don't print warning about "wrong" RPC buffer

[patchbot@xxxxxxx]

commit aace5466996e743a087153ad3f9d8fcf11a76c56
Author:     Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
AuthorDate: Mon Oct 5 09:12:32 2020 +0000
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Tue Oct 20 13:20:28 2020 -0700

    arm: optee: don't print warning about "wrong" RPC buffer
    
    The OP-TEE mediator tracks the cookie value of the last buffer which was
    requested by OP-TEE. This tracked value serves one important purpose: if
    OP-TEE wants to request another buffer, we know that it finished
    importing the previous one and we can free the page list associated with
    it.
    
    Also, we had a false premise that OP_TEE frees requested buffers in
    reversed order. So we checked rpc_data_cookie during handling of the
    OPTEE_RPC_CMD_SHM_FREE call and printed a warning if the cookie of the
    buffer which is requested to be freed differs from the last allocated
    one.
    
    During testing of RPMB FS services I discovered that RPMB code frees
    request and response buffers in the same order is it allocated them. And
    this is perfectly fine, actually.
    
    So, we are removing mentioned warning message in Xen, as it is perfectly
    normal to free buffers in arbitrary order.
    
    Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    [stefano: fix grammar]
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
---
 xen/arch/arm/tee/optee.c | 20 +-------------------
 1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
index 8a39fe33b0..ee85359742 100644
--- a/xen/arch/arm/tee/optee.c
+++ b/xen/arch/arm/tee/optee.c
@@ -1127,25 +1127,7 @@ static int handle_rpc_return(struct optee_domain *ctx,
          */
         if ( shm_rpc->xen_arg->cmd == OPTEE_RPC_CMD_SHM_FREE )
         {
-            uint64_t cookie = shm_rpc->xen_arg->params[0].u.value.b;
-
-            free_optee_shm_buf(ctx, cookie);
-
-            /*
-             * OP-TEE asks to free the buffer, but this is not the same
-             * buffer we previously allocated for it. While nothing
-             * prevents OP-TEE from asking this, it is the strange
-             * situation. This may or may not be caused by a bug in
-             * OP-TEE or mediator. But is better to print warning.
-             */
-            if ( call->rpc_data_cookie && call->rpc_data_cookie != cookie )
-            {
-                gprintk(XENLOG_ERR,
-                        "Saved RPC cookie does not corresponds to OP-TEE's 
(%"PRIx64" != %"PRIx64")\n",
-                        call->rpc_data_cookie, cookie);
-
-                WARN();
-            }
+            free_optee_shm_buf(ctx, shm_rpc->xen_arg->params[0].u.value.b);
             call->rpc_data_cookie = 0;
         }
         unmap_domain_page(shm_rpc->xen_arg);
--
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