[PATCH v11 15/26] gunyah: rsc_mgr: Add platform ops on mem_lend/mem_reclaim

[Elliot Berman]

On Qualcomm platforms, there is a firmware entity which controls access
to physical pages. In order to share memory with another VM, this entity
needs to be informed that the guest VM should have access to the memory.

Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@xxxxxxxxxxx>
Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@xxxxxxxxxxx>
Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
---
 drivers/virt/gunyah/Kconfig                 |  4 ++
 drivers/virt/gunyah/Makefile                |  1 +
 drivers/virt/gunyah/gunyah_platform_hooks.c | 80 +++++++++++++++++++++
 drivers/virt/gunyah/rsc_mgr.h               |  3 +
 drivers/virt/gunyah/rsc_mgr_rpc.c           | 18 ++++-
 include/linux/gunyah_rsc_mgr.h              | 17 +++++
 6 files changed, 121 insertions(+), 2 deletions(-)
 create mode 100644 drivers/virt/gunyah/gunyah_platform_hooks.c

diff --git a/drivers/virt/gunyah/Kconfig b/drivers/virt/gunyah/Kconfig
index 1a737694c333..de815189dab6 100644
--- a/drivers/virt/gunyah/Kconfig
+++ b/drivers/virt/gunyah/Kconfig
@@ -4,6 +4,7 @@ config GUNYAH
 	tristate "Gunyah Virtualization drivers"
 	depends on ARM64
 	depends on MAILBOX
+	select GUNYAH_PLATFORM_HOOKS
 	help
 	  The Gunyah drivers are the helper interfaces that run in a guest VM
 	  such as basic inter-VM IPC and signaling mechanisms, and higher level
@@ -11,3 +12,6 @@ config GUNYAH
 
 	  Say Y/M here to enable the drivers needed to interact in a Gunyah
 	  virtual environment.
+
+config GUNYAH_PLATFORM_HOOKS
+	tristate
diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
index ff8bc4925392..6b8f84dbfe0d 100644
--- a/drivers/virt/gunyah/Makefile
+++ b/drivers/virt/gunyah/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
 obj-$(CONFIG_GUNYAH) += gunyah.o
+obj-$(CONFIG_GUNYAH_PLATFORM_HOOKS) += gunyah_platform_hooks.o
 
 gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o vm_mgr_mm.o
 obj-$(CONFIG_GUNYAH) += gunyah_rsc_mgr.o
diff --git a/drivers/virt/gunyah/gunyah_platform_hooks.c b/drivers/virt/gunyah/gunyah_platform_hooks.c
new file mode 100644
index 000000000000..60da0e154e98
--- /dev/null
+++ b/drivers/virt/gunyah/gunyah_platform_hooks.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/rwsem.h>
+#include <linux/gunyah_rsc_mgr.h>
+
+#include "rsc_mgr.h"
+
+static struct gh_rm_platform_ops *rm_platform_ops;
+static DECLARE_RWSEM(rm_platform_ops_lock);
+
+int gh_rm_platform_pre_mem_share(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel)
+{
+	int ret = 0;
+
+	down_read(&rm_platform_ops_lock);
+	if (rm_platform_ops && rm_platform_ops->pre_mem_share)
+		ret = rm_platform_ops->pre_mem_share(rm, mem_parcel);
+	up_read(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gh_rm_platform_pre_mem_share);
+
+int gh_rm_platform_post_mem_reclaim(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel)
+{
+	int ret = 0;
+
+	down_read(&rm_platform_ops_lock);
+	if (rm_platform_ops && rm_platform_ops->post_mem_reclaim)
+		ret = rm_platform_ops->post_mem_reclaim(rm, mem_parcel);
+	up_read(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gh_rm_platform_post_mem_reclaim);
+
+int gh_rm_register_platform_ops(struct gh_rm_platform_ops *platform_ops)
+{
+	int ret = 0;
+
+	down_write(&rm_platform_ops_lock);
+	if (!rm_platform_ops)
+		rm_platform_ops = platform_ops;
+	else
+		ret = -EEXIST;
+	up_write(&rm_platform_ops_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gh_rm_register_platform_ops);
+
+void gh_rm_unregister_platform_ops(struct gh_rm_platform_ops *platform_ops)
+{
+	down_write(&rm_platform_ops_lock);
+	if (rm_platform_ops == platform_ops)
+		rm_platform_ops = NULL;
+	up_write(&rm_platform_ops_lock);
+}
+EXPORT_SYMBOL_GPL(gh_rm_unregister_platform_ops);
+
+static void _devm_gh_rm_unregister_platform_ops(void *data)
+{
+	gh_rm_unregister_platform_ops(data);
+}
+
+int devm_gh_rm_register_platform_ops(struct device *dev, struct gh_rm_platform_ops *ops)
+{
+	int ret;
+
+	ret = gh_rm_register_platform_ops(ops);
+	if (ret)
+		return ret;
+
+	return devm_add_action(dev, _devm_gh_rm_unregister_platform_ops, ops);
+}
+EXPORT_SYMBOL_GPL(devm_gh_rm_register_platform_ops);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Gunyah Platform Hooks");
diff --git a/drivers/virt/gunyah/rsc_mgr.h b/drivers/virt/gunyah/rsc_mgr.h
index 3665ebc7b020..6838e736f361 100644
--- a/drivers/virt/gunyah/rsc_mgr.h
+++ b/drivers/virt/gunyah/rsc_mgr.h
@@ -13,4 +13,7 @@ struct gh_rm;
 int gh_rm_call(struct gh_rm *rsc_mgr, u32 message_id, void *req_buff, size_t req_buf_size,
 		void **resp_buf, size_t *resp_buf_size);
 
+int gh_rm_platform_pre_mem_share(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel);
+int gh_rm_platform_post_mem_reclaim(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel);
+
 #endif
diff --git a/drivers/virt/gunyah/rsc_mgr_rpc.c b/drivers/virt/gunyah/rsc_mgr_rpc.c
index 3df15ad5b97d..733be4dc8dd2 100644
--- a/drivers/virt/gunyah/rsc_mgr_rpc.c
+++ b/drivers/virt/gunyah/rsc_mgr_rpc.c
@@ -204,6 +204,12 @@ static int gh_rm_mem_lend_common(struct gh_rm *rm, u32 message_id, struct gh_rm_
 	if (!msg)
 		return -ENOMEM;
 
+	ret = gh_rm_platform_pre_mem_share(rm, p);
+	if (ret) {
+		kfree(msg);
+		return ret;
+	}
+
 	req_header = msg;
 	acl_section = (void *)req_header + sizeof(*req_header);
 	mem_section = (void *)acl_section + struct_size(acl_section, entries, p->n_acl_entries);
@@ -227,8 +233,10 @@ static int gh_rm_mem_lend_common(struct gh_rm *rm, u32 message_id, struct gh_rm_
 	ret = gh_rm_call(rm, message_id, msg, msg_size, (void **)&resp, &resp_size);
 	kfree(msg);
 
-	if (ret)
+	if (ret) {
+		gh_rm_platform_post_mem_reclaim(rm, p);
 		return ret;
+	}
 
 	p->mem_handle = le32_to_cpu(*resp);
 
@@ -283,8 +291,14 @@ int gh_rm_mem_reclaim(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel)
 	struct gh_rm_mem_release_req req = {
 		.mem_handle = cpu_to_le32(parcel->mem_handle),
 	};
+	int ret;
+
+	ret = gh_rm_call(rm, GH_RM_RPC_MEM_RECLAIM, &req, sizeof(req), NULL, NULL);
+	/* Do not call platform mem reclaim hooks: the reclaim didn't happen*/
+	if (ret)
+		return ret;
 
-	return gh_rm_call(rm, GH_RM_RPC_MEM_RECLAIM, &req, sizeof(req), NULL, NULL);
+	return gh_rm_platform_post_mem_reclaim(rm, parcel);
 }
 
 /**
diff --git a/include/linux/gunyah_rsc_mgr.h b/include/linux/gunyah_rsc_mgr.h
index 8b0b46f28e39..515087931a2b 100644
--- a/include/linux/gunyah_rsc_mgr.h
+++ b/include/linux/gunyah_rsc_mgr.h
@@ -145,4 +145,21 @@ int gh_rm_get_hyp_resources(struct gh_rm *rm, u16 vmid,
 				struct gh_rm_hyp_resources **resources);
 int gh_rm_get_vmid(struct gh_rm *rm, u16 *vmid);
 
+struct gunyah_rm_platform_ops {
+	int (*pre_mem_share)(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel);
+	int (*post_mem_reclaim)(struct gh_rm *rm, struct gh_rm_mem_parcel *mem_parcel);
+};
+
+#if IS_ENABLED(CONFIG_GUNYAH_PLATFORM_HOOKS)
+int gh_rm_register_platform_ops(struct gh_rm_platform_ops *platform_ops);
+void gh_rm_unregister_platform_ops(struct gh_rm_platform_ops *platform_ops);
+int devm_gh_rm_register_platform_ops(struct device *dev, struct gh_rm_platform_ops *ops);
+#else
+static inline int gh_rm_register_platform_ops(struct gh_rm_platform_ops *platform_ops)
+	{ return 0; }
+static inline void gh_rm_unregister_platform_ops(struct gh_rm_platform_ops *platform_ops) { }
+static inline int devm_gh_rm_register_platform_ops(struct device *dev,
+	struct gh_rm_platform_ops *ops) { return 0; }
+#endif
+
 #endif
-- 
2.39.2