[dpdk-dev] [PATCH 2/2] mem: fix freeing an IVSHMEM memzone

[Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>]

There is no sync between host and guest to allow removal of memzones,
and freeing them result in undefined behavior.

In the guest, we identify IVSHMEM memsegs/memzones by having
ioremap_addr != 0. In the host, nothing is done to the memzone, meaning
ioremap_addr == 0.

As a solution, mark memzones being added to IVSHMEM in the host, by
setting ioremap_addr, then return an error whenever we try to free an
IVSHMEM memzone.

Fixes: ff909fe21f0 ("mem: introduce memzone freeing")

Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
---
 lib/librte_eal/common/eal_common_memzone.c  |  8 ++++++++
 lib/librte_eal/common/include/rte_memzone.h |  4 +++-
 lib/librte_ivshmem/rte_ivshmem.c            | 15 +++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/librte_eal/common/eal_common_memzone.c b/lib/librte_eal/common/eal_common_memzone.c
index 7b1d77e..febc56b 100644
--- a/lib/librte_eal/common/eal_common_memzone.c
+++ b/lib/librte_eal/common/eal_common_memzone.c
@@ -322,6 +322,14 @@ rte_memzone_free(const struct rte_memzone *mz)
 	idx = idx / sizeof(struct rte_memzone);
 
 	addr = mcfg->memzone[idx].addr;
+#ifdef RTE_LIBRTE_IVSHMEM
+	/*
+	 * If ioremap_addr is set, it's an IVSHMEM memzone and we cannot
+	 * free it.
+	 */
+	if (mcfg->memzone[idx].ioremap_addr != 0)
+		ret = -EINVAL;
+#endif
 	if (addr == NULL)
 		ret = -EINVAL;
 	else if (mcfg->memzone_cnt == 0) {
diff --git a/lib/librte_eal/common/include/rte_memzone.h b/lib/librte_eal/common/include/rte_memzone.h
index 38e5f5b..6a92222 100644
--- a/lib/librte_eal/common/include/rte_memzone.h
+++ b/lib/librte_eal/common/include/rte_memzone.h
@@ -258,10 +258,12 @@ const struct rte_memzone *rte_memzone_reserve_bounded(const char *name,
 /**
  * Free a memzone.
  *
+ * Note: an IVSHMEM zone cannot be freed.
+ *
  * @param mz
  *   A pointer to the memzone
  * @return
- *  -EINVAL - invalid parameter
+ *  -EINVAL - invalid parameter, IVSHMEM memzone.
  *  0 - success
  */
 int rte_memzone_free(const struct rte_memzone *mz);
diff --git a/lib/librte_ivshmem/rte_ivshmem.c b/lib/librte_ivshmem/rte_ivshmem.c
index 9621906..8fc4b57 100644
--- a/lib/librte_ivshmem/rte_ivshmem.c
+++ b/lib/librte_ivshmem/rte_ivshmem.c
@@ -504,7 +504,22 @@ add_memzone_to_metadata(const struct rte_memzone * mz,
 				config->metadata->name);
 		goto fail;
 	}
+#ifdef RTE_LIBRTE_IVSHMEM
+	struct rte_mem_config *mcfg;
+	unsigned int idx;
 
+	mcfg = rte_eal_get_configuration()->mem_config;
+
+	rte_rwlock_write_lock(&mcfg->mlock);
+
+	idx = ((uintptr_t)mz - (uintptr_t)mcfg->memzone);
+	idx = idx / sizeof(struct rte_memzone);
+
+	/* mark the memzone not freeable */
+	mcfg->memzone[idx].ioremap_addr = mz->phys_addr;
+
+	rte_rwlock_write_unlock(&mcfg->mlock);
+#endif
 	rte_spinlock_unlock(&config->sl);
 	return 0;
 fail:
-- 
1.9.3