Re: [Tee-dev] [PATCH v3 09/11] optee: add support for RPC commands

Hi Volodymyr,

On 18/12/2018 21:11, Volodymyr Babchuk wrote:

From: Volodymyr Babchuk vlad.babchuk@gmail.com

OP-TEE can issue multiple RPC requests. We are interested mostly in request that asks NW to allocate/free shared memory for OP-TEE needs, because mediator need to do address translation in the same

NIT: the mediator needs

way as it was done for shared buffers registered by NW.

As mediator now accesses shared command buffer, we need to shadow it in the same way, as we shadow request buffers for STD calls.

This is a bit confusing, does it means patch #8 is not doing the right thing?

Signed-off-by: Volodymyr Babchuk vlad.babchuk@gmail.com

Changes from v2:

• Use access_guest_memory_by_ipa() instead of direct mapping

xen/arch/arm/tee/optee.c | 136 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 130 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c index cfc3b34df7..bf3535946d 100644 --- a/xen/arch/arm/tee/optee.c +++ b/xen/arch/arm/tee/optee.c @@ -67,6 +67,8 @@ struct optee_std_call { struct shm_rpc { struct list_head list; struct page_info *guest_page;

• struct optee_msg_arg *xen_arg;
• paddr_t guest_ipa; uint64_t cookie; };

@@ -290,6 +292,11 @@ static struct shm_rpc *allocate_and_pin_shm_rpc(struct optee_domain *ctx, P2M_ALLOC); if ( !shm_rpc->guest_page ) goto err;

• shm_rpc->guest_ipa = gaddr;
• shm_rpc->xen_arg = alloc_xenheap_page();

Based on the discussion in patch #6, I think you want to use to allocate the memory from domheap.

• if ( !shm_rpc->xen_arg )

•    goto err;
  

shm_rpc->cookie = cookie; @@ -313,6 +320,7 @@ static struct shm_rpc *allocate_and_pin_shm_rpc(struct optee_domain *ctx, err: atomic_dec(&ctx->shm_rpc_count); put_page(shm_rpc->guest_page);

• free_xenheap_page(shm_rpc->xen_arg); xfree(shm_rpc);

return NULL; @@ -339,12 +347,32 @@ static void free_shm_rpc(struct optee_domain *ctx, uint64_t cookie) if ( !found ) return;

• free_xenheap_page(shm_rpc->xen_arg);

• ASSERT(shm_rpc->guest_page);
  put_page(shm_rpc->guest_page);
  

xfree(shm_rpc); } +static struct shm_rpc *find_shm_rpc(struct optee_domain *ctx, uint64_t cookie) +{

• struct shm_rpc *shm_rpc;
• spin_lock(&ctx->lock);
• list_for_each_entry( shm_rpc, &ctx->shm_rpc_list, list )
• {

•    if ( shm_rpc->cookie == cookie )
  

•    {
  

•            spin_unlock(&ctx->lock);
  

•            return shm_rpc;
  

•    }
  

• }
• spin_unlock(&ctx->lock);
• return NULL;

+}

• static struct optee_shm_buf *allocate_optee_shm_buf(struct optee_domain *ctx, uint64_t cookie, unsigned int pages_cnt)

@@ -712,6 +740,33 @@ static void copy_std_request_back(struct optee_domain *ctx, put_page(page); } +static void handle_rpc_return(struct optee_domain *ctx,

•                         struct cpu_user_regs *regs,
  

•                         struct optee_std_call *call)
  

+{

• call->rpc_params[0] = get_user_reg(regs, 1);
• call->rpc_params[1] = get_user_reg(regs, 2);
• call->optee_thread_id = get_user_reg(regs, 3);
• call->rpc_op = OPTEE_SMC_RETURN_GET_RPC_FUNC(get_user_reg(regs, 0));
• if ( call->rpc_op == OPTEE_SMC_RPC_FUNC_CMD )
• {

•    /* Copy RPC request from shadowed buffer to guest */
  

•    uint64_t cookie = get_user_reg(regs, 1) << 32 | get_user_reg(regs, 2);
  

I am afraid this is not going to work correctly. get_user_reg return a 64-bit value, so if the top bit are non-zero then the cookie value will actually be wrong. It is not clear to me whether the bits [63:32] should be 0, so the best is to ignore them.

Given you use similar construction in a few places in the code, I would introduce a new helper that take 2 register indexes and return the 64-bit value.

•    struct shm_rpc *shm_rpc = find_shm_rpc(ctx, cookie);
  

Newline here please.

•    if ( !shm_rpc )
  

•    {
  

•        gprintk(XENLOG_ERR, "Can't find SHM-RPC with cookie %lx\n", cookie);
  

•        return;
  

•    }
  

•    access_guest_memory_by_ipa(current->domain,
  

•                    shm_rpc->guest_ipa,
  

•                    shm_rpc->xen_arg,
  

•                    OPTEE_MSG_GET_ARG_SIZE(shm_rpc->xen_arg->num_params),
  

•                    true);
  

• }

+}

• static void execute_std_call(struct optee_domain *ctx, struct cpu_user_regs *regs, struct optee_std_call *call)

@@ -723,10 +778,7 @@ static void execute_std_call(struct optee_domain *ctx, optee_ret = get_user_reg(regs, 0); if ( OPTEE_SMC_RETURN_IS_RPC(optee_ret) ) {

•    call->rpc_params[0] = get_user_reg(regs, 1);
  

•    call->rpc_params[1] = get_user_reg(regs, 2);
  

•    call->optee_thread_id = get_user_reg(regs, 3);
  

•    call->rpc_op = OPTEE_SMC_RETURN_GET_RPC_FUNC(optee_ret);
  

•    handle_rpc_return(ctx, regs, call);
  

Please avoid code movement and introduce the function in the patch that was adding this code.

      put_std_call(ctx, call);
      return;
  }

@@ -787,6 +839,78 @@ err: return false; } +static void handle_rpc_cmd_alloc(struct optee_domain *ctx,

•                             struct cpu_user_regs *regs,
  

•                             struct optee_std_call *call,
  

•                             struct shm_rpc *shm_rpc)
  

+{

• if ( shm_rpc->xen_arg->params[0].attr != (OPTEE_MSG_ATTR_TYPE_TMEM_OUTPUT |

•                                        OPTEE_MSG_ATTR_NONCONTIG) )
  

• {

•    gprintk(XENLOG_WARNING, "Invalid attrs for shared mem buffer\n");
  

I would use gdprintk here and print the attributes to help the developer.

•    return;
  

• }
• /* Last entry in non_contig array is used to hold RPC-allocated buffer */
• if ( call->non_contig[MAX_NONCONTIG_ENTRIES - 1] )
• {

•    free_xenheap_pages(call->non_contig[MAX_NONCONTIG_ENTRIES - 1],
  

•                       call->non_contig_order[MAX_NONCONTIG_ENTRIES - 1]);
  

•    call->non_contig[MAX_NONCONTIG_ENTRIES - 1] = NULL;
  

• }
• translate_noncontig(ctx, call, shm_rpc->xen_arg->params + 0,

•                    MAX_NONCONTIG_ENTRIES - 1);
  

+}

+static void handle_rpc_cmd(struct optee_domain *ctx, struct cpu_user_regs *regs,

•                       struct optee_std_call *call)
  

+{

• struct shm_rpc *shm_rpc;
• uint64_t cookie;
• size_t arg_size;
• cookie = get_user_reg(regs, 1) << 32 | get_user_reg(regs, 2);

See above.

• shm_rpc = find_shm_rpc(ctx, cookie);
• if ( !shm_rpc )
• {

•    gprintk(XENLOG_ERR, "Can't find SHM-RPC with cookie %lx\n", cookie);
  

•    return;
  

• }
• /* First, copy only header to read number of arguments */
• access_guest_memory_by_ipa(current->domain, shm_rpc->guest_ipa,

•                           shm_rpc->xen_arg, sizeof(struct optee_msg_arg),
  

•                           false);
  

This can return an error.

• arg_size = OPTEE_MSG_GET_ARG_SIZE(shm_rpc->xen_arg->num_params);
• if ( arg_size > OPTEE_MSG_NONCONTIG_PAGE_SIZE )

•    return;
  

• /* Read the whole command structure */
• access_guest_memory_by_ipa(current->domain, shm_rpc->guest_ipa,

•                           shm_rpc->xen_arg, arg_size, false);
  

Ditto.

• switch (shm_rpc->xen_arg->cmd)
• {
• case OPTEE_MSG_RPC_CMD_GET_TIME:

•    break;
  

• case OPTEE_MSG_RPC_CMD_WAIT_QUEUE:

•    break;
  

• case OPTEE_MSG_RPC_CMD_SUSPEND:

•    break;
  

• case OPTEE_MSG_RPC_CMD_SHM_ALLOC:

•    handle_rpc_cmd_alloc(ctx, regs, call, shm_rpc);
  

•    break;
  

• case OPTEE_MSG_RPC_CMD_SHM_FREE:

•    free_optee_shm_buf(ctx, shm_rpc->xen_arg->params[0].u.value.b);
  

•    break;
  

• default:

•    break;
  

• }

+}

• static void handle_rpc_func_alloc(struct optee_domain *ctx, struct cpu_user_regs *regs) {

@@ -807,7 +931,7 @@ static void handle_rpc_func_alloc(struct optee_domain *ctx, ptr = 0; } else

•        ptr = page_to_maddr(shm_rpc->guest_page);
  

•        ptr = virt_to_maddr(shm_rpc->xen_arg);
  

set_user_reg(regs, 1, ptr >> 32); set_user_reg(regs, 2, ptr & 0xFFFFFFFF); @@ -839,7 +963,7 @@ static bool handle_rpc(struct optee_domain *ctx, struct cpu_user_regs *regs) case OPTEE_SMC_RPC_FUNC_FOREIGN_INTR: break; case OPTEE_SMC_RPC_FUNC_CMD:

•    /* TODO: Add handling */
  

•    handle_rpc_cmd(ctx, regs, call);
      break;
  }
  

Cheers,