[PATCH 05/12] xen/arm: ffa: Fix PARTINFO RX release errors

[Bertrand Marquis <bertrand.marquis@xxxxxxx>]

On PARTITION_INFO_GET error paths, Xen unconditionally called
FFA_RX_RELEASE for the SPMC RX buffer. If the SPMC didn't grant RX
ownership (i.e., the call failed early), this issues a spurious release
that returns DENIED and produces warnings.

Modify ffa_rxtx_spmc_rx_release() to return the release status and let
callers choose whether to log it. Only issue FFA_RX_RELEASE after a
successful PARTINFO SMC, while always releasing the local RX lock to
avoid deadlocks.

Update handle_partition_info_get() to only release the SPMC RX buffer
after successful fw_ret checks, and ignore release errors during the
error path.

Functional impact: eliminates spurious FFA_RX_RELEASE calls and
associated DENIED warnings when PARTITION_INFO_GET fails before
obtaining SPMC RX buffer ownership.

Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
 xen/arch/arm/tee/ffa_partinfo.c | 14 ++++++++++++--
 xen/arch/arm/tee/ffa_private.h  |  2 +-
 xen/arch/arm/tee/ffa_rxtx.c     | 14 +++++++++-----
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/xen/arch/arm/tee/ffa_partinfo.c b/xen/arch/arm/tee/ffa_partinfo.c
index bf906ed0c88f..6b01c4abe915 100644
--- a/xen/arch/arm/tee/ffa_partinfo.c
+++ b/xen/arch/arm/tee/ffa_partinfo.c
@@ -92,9 +92,11 @@ static int32_t ffa_get_sp_partinfo(struct ffa_uuid uuid, 
uint32_t *sp_count,
                                    uint32_t dst_size)
 {
     int32_t ret;
+    int32_t release_ret;
     uint32_t src_size, real_sp_count;
     void *src_buf;
     uint32_t count = 0;
+    bool spmc_ok = false;
 
     /* We need to use the RX buffer to receive the list */
     src_buf = ffa_rxtx_spmc_rx_acquire();
@@ -104,6 +106,7 @@ static int32_t ffa_get_sp_partinfo(struct ffa_uuid uuid, 
uint32_t *sp_count,
     ret = ffa_partition_info_get(uuid, 0, &real_sp_count, &src_size);
     if ( ret )
         goto out;
+    spmc_ok = true;
 
     /* Validate the src_size we got */
     if ( src_size < sizeof(struct ffa_partition_info_1_0) ||
@@ -157,7 +160,10 @@ static int32_t ffa_get_sp_partinfo(struct ffa_uuid uuid, 
uint32_t *sp_count,
     *sp_count = count;
 
 out:
-    ffa_rxtx_spmc_rx_release();
+    release_ret = ffa_rxtx_spmc_rx_release(spmc_ok);
+    if ( release_ret )
+        gprintk(XENLOG_WARNING,
+                "ffa: Error releasing SPMC RX buffer: %d\n", release_ret);
     return ret;
 }
 
@@ -507,6 +513,7 @@ bool ffa_partinfo_init(void)
     int32_t e;
     void *spmc_rx;
     struct ffa_uuid nil_uuid = { .val = { 0ULL, 0ULL } };
+    bool spmc_ok = false;
 
     if ( !ffa_fw_supports_fid(FFA_PARTITION_INFO_GET) ||
          !ffa_fw_supports_fid(FFA_MSG_SEND_DIRECT_REQ_32))
@@ -522,6 +529,7 @@ bool ffa_partinfo_init(void)
         printk(XENLOG_ERR "ffa: Failed to get list of SPs: %d\n", e);
         goto out;
     }
+    spmc_ok = true;
 
     if ( count >= FFA_MAX_NUM_SP )
     {
@@ -533,7 +541,9 @@ bool ffa_partinfo_init(void)
     ret = init_subscribers(spmc_rx, count, fpi_size);
 
 out:
-    ffa_rxtx_spmc_rx_release();
+    e = ffa_rxtx_spmc_rx_release(spmc_ok);
+    if ( e )
+        printk(XENLOG_WARNING "ffa: Error releasing SPMC RX buffer: %d\n", e);
     return ret;
 }
 
diff --git a/xen/arch/arm/tee/ffa_private.h b/xen/arch/arm/tee/ffa_private.h
index 58562d8e733c..461e87f6f9c4 100644
--- a/xen/arch/arm/tee/ffa_private.h
+++ b/xen/arch/arm/tee/ffa_private.h
@@ -458,7 +458,7 @@ int32_t ffa_endpoint_domain_lookup(uint16_t endpoint_id, 
struct domain **d_out,
 bool ffa_rxtx_spmc_init(void);
 void ffa_rxtx_spmc_destroy(void);
 void *ffa_rxtx_spmc_rx_acquire(void);
-void ffa_rxtx_spmc_rx_release(void);
+int32_t ffa_rxtx_spmc_rx_release(bool notify_fw);
 void *ffa_rxtx_spmc_tx_acquire(void);
 void ffa_rxtx_spmc_tx_release(void);
 
diff --git a/xen/arch/arm/tee/ffa_rxtx.c b/xen/arch/arm/tee/ffa_rxtx.c
index 7d8bb4f4d031..50758fb57cdf 100644
--- a/xen/arch/arm/tee/ffa_rxtx.c
+++ b/xen/arch/arm/tee/ffa_rxtx.c
@@ -375,18 +375,22 @@ void *ffa_rxtx_spmc_rx_acquire(void)
     return NULL;
 }
 
-void ffa_rxtx_spmc_rx_release(void)
+int32_t ffa_rxtx_spmc_rx_release(bool notify_fw)
 {
     int32_t ret;
 
     ASSERT(spin_is_locked(&ffa_spmc_rx_lock));
 
-    /* Inform the SPMC that we are done with our RX buffer */
-    ret = ffa_simple_call(FFA_RX_RELEASE, 0, 0, 0, 0);
-    if ( ret != FFA_RET_OK )
-        printk(XENLOG_DEBUG "Error releasing SPMC RX buffer: %d\n", ret);
+    if ( notify_fw )
+    {
+        /* Inform the SPMC that we are done with our RX buffer */
+        ret = ffa_simple_call(FFA_RX_RELEASE, 0, 0, 0, 0);
+    }
+    else
+        ret = FFA_RET_OK;
 
     spin_unlock(&ffa_spmc_rx_lock);
+    return ret;
 }
 
 void *ffa_rxtx_spmc_tx_acquire(void)
-- 
2.50.1 (Apple Git-155)