[XEN PATCH v8 10/22] xen/arm: ffa: map SPMC rx/tx buffers

[Jens Wiklander <jens.wiklander@xxxxxxxxxx>]

When initializing the FF-A mediator map the RX and TX buffers shared with
the SPMC.

These buffer are later used to to transmit data that cannot be passed in
registers only.

Adds a check that the SP supports the needed FF-A features
FFA_RXTX_MAP_64 and FFA_RXTX_UNMAP.

Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
---
 xen/arch/arm/tee/ffa.c | 50 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
index f2cce955d981..054121fe4321 100644
--- a/xen/arch/arm/tee/ffa.c
+++ b/xen/arch/arm/tee/ffa.c
@@ -12,6 +12,7 @@
 #include <xen/errno.h>
 #include <xen/init.h>
 #include <xen/lib.h>
+#include <xen/mm.h>
 #include <xen/sched.h>
 #include <xen/sizes.h>
 #include <xen/types.h>
@@ -67,6 +68,12 @@
  */
 #define FFA_PAGE_SIZE                   SZ_4K
 
+/*
+ * The number of pages used for each of the RX and TX buffers shared with
+ * the SPMC.
+ */
+#define FFA_RXTX_PAGE_COUNT             1
+
 /*
  * Flags and field values used for the MSG_SEND_DIRECT_REQ/RESP:
  * BIT(31): Framework or partition message
@@ -161,6 +168,13 @@ struct ffa_ctx {
 /* Negotiated FF-A version to use with the SPMC */
 static uint32_t ffa_version __ro_after_init;
 
+/*
+ * Our rx/tx buffers shared with the SPMC. FFA_RXTX_PAGE_COUNT is the
+ * number of pages used in each of these buffers.
+ */
+static void *ffa_rx __read_mostly;
+static void *ffa_tx __read_mostly;
+
 static bool ffa_get_version(uint32_t *vers)
 {
     const struct arm_smccc_1_2_regs arg = {
@@ -231,6 +245,12 @@ static bool check_mandatory_feature(uint32_t id)
     return !ret;
 }
 
+static int32_t ffa_rxtx_map(paddr_t tx_addr, paddr_t rx_addr,
+                            uint32_t page_count)
+{
+    return ffa_simple_call(FFA_RXTX_MAP_64, tx_addr, rx_addr, page_count, 0);
+}
+
 static uint16_t get_vm_id(const struct domain *d)
 {
     /* +1 since 0 is reserved for the hypervisor in FF-A */
@@ -389,6 +409,7 @@ static int ffa_relinquish_resources(struct domain *d)
 static bool ffa_probe(void)
 {
     uint32_t vers;
+    int e;
     unsigned int major_vers;
     unsigned int minor_vers;
 
@@ -435,12 +456,39 @@ static bool ffa_probe(void)
      * TODO save result of checked features and use that information to
      * accept or reject requests from guests.
      */
-    if ( !check_mandatory_feature(FFA_MSG_SEND_DIRECT_REQ_32) )
+    if (
+         !check_mandatory_feature(FFA_RXTX_MAP_64) ||
+         !check_mandatory_feature(FFA_RXTX_UNMAP) ||
+         !check_mandatory_feature(FFA_MSG_SEND_DIRECT_REQ_32) )
+        return false;
+
+    ffa_rx = alloc_xenheap_pages(get_order_from_pages(FFA_RXTX_PAGE_COUNT), 0);
+    if ( !ffa_rx )
         return false;
 
+    ffa_tx = alloc_xenheap_pages(get_order_from_pages(FFA_RXTX_PAGE_COUNT), 0);
+    if ( !ffa_tx )
+        goto err_free_ffa_rx;
+
+    e = ffa_rxtx_map(__pa(ffa_tx), __pa(ffa_rx), FFA_RXTX_PAGE_COUNT);
+    if ( e )
+    {
+        printk(XENLOG_ERR "ffa: Failed to map rxtx: error %d\n", e);
+        goto err_free_ffa_tx;
+    }
     ffa_version = vers;
 
     return true;
+
+err_free_ffa_tx:
+    free_xenheap_pages(ffa_tx, 0);
+    ffa_tx = NULL;
+err_free_ffa_rx:
+    free_xenheap_pages(ffa_rx, 0);
+    ffa_rx = NULL;
+    ffa_version = 0;
+
+    return false;
 }
 
 static const struct tee_mediator_ops ffa_ops =
-- 
2.34.1