On 5/9/23 3:47 PM, Elliot Berman wrote:
> 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.
You might be able to avoid the lock by using rcu_assign_pointer() and
rcu_dereference(), but I'm not recommending it (because I'm not sure).
I have one more suggestion below.
Reviewed-by: Alex Elder <elder@linaro.org>
> Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> ---
> drivers/virt/gunyah/Kconfig | 4 ++
> drivers/virt/gunyah/Makefile | 2 +
> 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, 122 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 bacf78b8fa33..4fbeee521d60 100644
> --- a/drivers/virt/gunyah/Makefile
> +++ b/drivers/virt/gunyah/Makefile
> @@ -1,4 +1,6 @@
> # SPDX-License-Identifier: GPL-2.0
>
> +obj-$(CONFIG_GUNYAH_PLATFORM_HOOKS) += gunyah_platform_hooks.o
> +
> gunyah-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o vm_mgr_mm.o
> obj-$(CONFIG_GUNYAH) += gunyah.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)
Can (should) platform_ops be declared as const? (I think it can,
that would be better as long as you don't expect operation function
pointers to be added after registration.) If you do that, all such
arguments will probably need to be updated to pointer-to-const.
> +{
> + 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);
. . .
@@ -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
@@ -1,4 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_GUNYAH_PLATFORM_HOOKS) += gunyah_platform_hooks.o
+
gunyah-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o vm_mgr_mm.o
obj-$(CONFIG_GUNYAH) += gunyah.o
new file mode 100644
@@ -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");
@@ -13,4 +13,7 @@ struct gh_rm;
int gh_rm_call(struct gh_rm *rsc_mgr, u32 message_id, const void *req_buf, 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
@@ -207,6 +207,12 @@ 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 + acl_section_size;
@@ -231,8 +237,10 @@ 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);
kfree(resp);
@@ -287,8 +295,14 @@ 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);
+ /* Only call the platform mem reclaim hooks if we reclaimed the memory */
+ 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);
}
/**
@@ -139,4 +139,21 @@ 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 gh_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