Re: [PATCH v10 15/26] gunyah: rsc_mgr: Add platform ops on mem_lend/mem_reclaim

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

On 14/02/2023 21:24, 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.
> 
> 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                |  1 +
>   drivers/virt/gunyah/gunyah_platform_hooks.c | 80 +++++++++++++++++++++
>   drivers/virt/gunyah/rsc_mgr.h               |  3 +
>   drivers/virt/gunyah/rsc_mgr_rpc.c           | 12 +++-
>   include/linux/gunyah_rsc_mgr.h              | 17 +++++
>   6 files changed, 115 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..e67e2361b592
> --- /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 gunyah_rm_platform_ops *rm_platform_ops;
> +static DECLARE_RWSEM(rm_platform_ops_lock);

Why do we need this read/write lock or this global rm_platform_ops here, 
AFAIU, there will be only one instance of platform_ops per platform.

This should be a core part of the gunyah and its driver early setup, 
that should give us pretty much lock less behaviour.

We should be able to determine by Hypervisor UUID that its on Qualcomm 
platform or not, during early gunyah setup which should help us setup 
the platfrom ops accordingly.

This should also help cleanup some of the gunyah code that was added 
futher down in this patchset.


--srini

> +
> +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 gunyah_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 gunyah_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 gunyah_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 9b23cefe02b0..e536169df41e 100644
> --- a/drivers/virt/gunyah/rsc_mgr.h
> +++ b/drivers/virt/gunyah/rsc_mgr.h
> @@ -74,6 +74,9 @@ struct gh_rm;
>   int gh_rm_call(struct gh_rm *rsc_mgr, u32 message_id, void *req_buff, size_t req_buff_size,
>   		void **resp_buf, size_t *resp_buff_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);
> +
>   /* Message IDs: Memory Management */
>   #define GH_RM_RPC_MEM_LEND			0x51000012
>   #define GH_RM_RPC_MEM_SHARE			0x51000013
> diff --git a/drivers/virt/gunyah/rsc_mgr_rpc.c b/drivers/virt/gunyah/rsc_mgr_rpc.c
> index 0c83b097fec9..0b12696bf069 100644
> --- a/drivers/virt/gunyah/rsc_mgr_rpc.c
> +++ b/drivers/virt/gunyah/rsc_mgr_rpc.c
> @@ -116,6 +116,12 @@ 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);
> @@ -139,8 +145,10 @@ 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);
>   
> @@ -204,7 +212,7 @@ int gh_rm_mem_reclaim(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel)
>   	if (ret)
>   		return ret;
>   
> -	return ret;
> +	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 9cffee6f9b4e..dc05d5b1e1a3 100644
> --- a/include/linux/gunyah_rsc_mgr.h
> +++ b/include/linux/gunyah_rsc_mgr.h
> @@ -147,4 +147,21 @@ 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 gunyah_rm_platform_ops *platform_ops);
> +void gh_rm_unregister_platform_ops(struct gunyah_rm_platform_ops *platform_ops);
> +int devm_gh_rm_register_platform_ops(struct device *dev, struct gunyah_rm_platform_ops *ops);
> +#else
> +static inline int gh_rm_register_platform_ops(struct gunyah_rm_platform_ops *platform_ops)
> +	{ return 0; }
> +static inline void gh_rm_unregister_platform_ops(struct gunyah_rm_platform_ops *platform_ops) { }
> +static inline int devm_gh_rm_register_platform_ops(struct device *dev,
> +	struct gunyah_rm_platform_ops *ops) { return 0; }
> +#endif
> +
>   #endif