adsprpc: tvm: Obtain buffer attributes to determine ownership and access

Query buffer's attributes to determine if buffer should be mapped to secure
context bank.
Query buffer's HLOS access and return error from TVM driver if HLOS has
access to buffer.

Change-Id: Ia6d02b28929e1126a01c69a8425b6797fbee3506

dsp/adsprpc.c

@@ -43,6 +43,7 @@
 #include "adsprpc_shared.h"
 #include <soc/qcom/qcom_ramdump.h>
 #include <soc/qcom/minidump.h>
+#include <soc/qcom/secure_buffer.h>
 #include <linux/delay.h>
 #include <linux/debugfs.h>
 #include <linux/pm_qos.h>
@@ -1159,6 +1160,77 @@ bail:
 	return err;
 }
 
+static int get_buffer_attr(struct dma_buf *buf, bool *exclusive_access, bool *hlos_access)
+{
+	const int *vmids_list = NULL, *perms = NULL;
+	int err = 0, vmids_list_len = 0;
+
+	*exclusive_access = false;
+	*hlos_access = false;
+	err = mem_buf_dma_buf_get_vmperm(buf, &vmids_list, &perms, &vmids_list_len);
+	if (err)
+		goto bail;
+
+	/*
+	 * If one VM has access to buffer and is the current VM,
+	 * then VM has exclusive access to buffer
+	 */
+	if (vmids_list_len == 1 && vmids_list[0] == mem_buf_current_vmid())
+		*exclusive_access = true;
+
+#if IS_ENABLED(CONFIG_MSM_ADSPRPC_TRUSTED)
+	/*
+	 * PVM (HLOS) can share buffers with TVM. In that case,
+	 * it is expected to relinquish its ownership to those buffers
+	 * before sharing. But if the PVM still retains access, then
+	 * these buffers cannot be used by TVM.
+	 */
+
+	for (int ii = 0; ii < vmids_list_len; ii++) {
+		if (vmids_list[ii] == VMID_HLOS) {
+			*hlos_access = true;
+			break;
+		}
+	}
+#endif
+
+bail:
+	return err;
+}
+
+static int set_buffer_secure_type(struct fastrpc_mmap *map)
+{
+	int err = 0;
+	bool hlos_access = false, exclusive_access = false;
+
+	VERIFY(err, 0 == (err = get_buffer_attr(map->buf, &exclusive_access, &hlos_access)));
+	if (err) {
+		ADSPRPC_ERR("failed to obtain buffer attributes for fd %d ret %d\n", map->fd, err);
+		err = -EBADFD;
+		goto bail;
+	}
+#if IS_ENABLED(CONFIG_MSM_ADSPRPC_TRUSTED)
+	if (hlos_access) {
+		ADSPRPC_ERR("Sharing HLOS buffer (fd %d) not allowed on TVM\n", map->fd);
+		err = -EACCES;
+		goto bail;
+	}
+#endif
+	/*
+	 * Secure buffers would always be owned by multiple VMs.
+	 * If current VM is the exclusive owner of a buffer, it is considered non-secure.
+	 * In PVM:
+	 *	- CPZ buffers are secure
+	 *	- All other buffers are non-secure
+	 * In TVM:
+	 *	- Since it is a secure environment by default, there are no explicit "secure" buffers
+	 *	- All buffers are marked "non-secure"
+	 */
+	map->secure = (exclusive_access) ? 0 : 1;
+bail:
+	return err;
+}
+
 static int fastrpc_mmap_create(struct fastrpc_file *fl, int fd, struct dma_buf *buf,
 	unsigned int attr, uintptr_t va, size_t len, int mflags,
 	struct fastrpc_mmap **ppmap)
@@ -1224,10 +1296,10 @@ static int fastrpc_mmap_create(struct fastrpc_file *fl, int fd, struct dma_buf *
 			err = -EBADFD;
 			goto bail;
 		}
+		err = set_buffer_secure_type(map);
+		if (err)
+			goto bail;
 
-#if !IS_ENABLED(CONFIG_MSM_ADSPRPC_TRUSTED)
-		map->secure = (mem_buf_dma_buf_exclusive_owner(map->buf)) ? 0 : 1;
-#endif
 		map->va = 0;
 		map->phys = 0;
 
@@ -1293,10 +1365,10 @@ static int fastrpc_mmap_create(struct fastrpc_file *fl, int fd, struct dma_buf *
 				goto bail;
 			}
 		}
+		err = set_buffer_secure_type(map);
+		if (err)
+			goto bail;
 
-#if !IS_ENABLED(CONFIG_MSM_ADSPRPC_TRUSTED)
-		map->secure = (mem_buf_dma_buf_exclusive_owner(map->buf)) ? 0 : 1;
-#endif
 		if (map->secure) {
 			if (!fl->secsctx)
 				err = fastrpc_session_alloc_secure_memory(chan, 1,