Commit 0aadb6a7 authored by Andrea Parri (Microsoft)'s avatar Andrea Parri (Microsoft) Committed by Wei Liu
Browse files

Drivers: hv: vmbus: Introduce vmbus_request_addr_match() 



The function can be used to retrieve and clear/remove a transation ID
from a channel requestor, provided the memory address corresponding to
the ID equals a specified address.  The function, and its 'lockless'
variant __vmbus_request_addr_match(), will be used by hv_pci.

Refactor vmbus_request_addr() to reuse the 'newly' introduced code.

No functional change.

Suggested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarAndrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220419122325.10078-5-parri.andrea@gmail.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent b03afa57

drivers/hv/channel.c

+47 −18
Original line number Diff line number Diff line
@@ -1279,17 +1279,11 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr) 
}

EXPORT_SYMBOL_GPL(vmbus_next_request_id);



/*

 * vmbus_request_addr - Returns the memory address stored at @trans_id

 * in @rqstor. Uses a spin lock to avoid race conditions.

 * @channel: Pointer to the VMbus channel struct

 * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's

 * next request id.

 */

u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)

/* As in vmbus_request_addr_match() but without the requestor lock */

u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,

			       u64 rqst_addr)

{

	struct vmbus_requestor *rqstor = &channel->requestor;

	unsigned long flags;

	u64 req_addr;



	/* Check rqstor has been initialized */
@@ -1300,25 +1294,60 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id) 
	if (!trans_id)

		return VMBUS_RQST_ERROR;



	spin_lock_irqsave(&rqstor->req_lock, flags);



	/* Data corresponding to trans_id is stored at trans_id - 1 */

	trans_id--;



	/* Invalid trans_id */

	if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {

		spin_unlock_irqrestore(&rqstor->req_lock, flags);

	if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap))

		return VMBUS_RQST_ERROR;

	}



	req_addr = rqstor->req_arr[trans_id];

	if (rqst_addr == VMBUS_RQST_ADDR_ANY || req_addr == rqst_addr) {

		rqstor->req_arr[trans_id] = rqstor->next_request_id;

		rqstor->next_request_id = trans_id;



		/* The already held spin lock provides atomicity */

		bitmap_clear(rqstor->req_bitmap, trans_id, 1);

	}



	return req_addr;

}

EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);



/*

 * vmbus_request_addr_match - Clears/removes @trans_id from the @channel's

 * requestor, provided the memory address stored at @trans_id equals @rqst_addr

 * (or provided @rqst_addr matches the sentinel value VMBUS_RQST_ADDR_ANY).

 *

 * Returns the memory address stored at @trans_id, or VMBUS_RQST_ERROR if

 * @trans_id is not contained in the requestor.

 *

 * Acquires and releases the requestor spin lock.

 */

u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,

			     u64 rqst_addr)

{

	struct vmbus_requestor *rqstor = &channel->requestor;

	unsigned long flags;

	u64 req_addr;



	spin_lock_irqsave(&rqstor->req_lock, flags);

	req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);

	spin_unlock_irqrestore(&rqstor->req_lock, flags);



	return req_addr;

}

EXPORT_SYMBOL_GPL(vmbus_request_addr_match);



/*

 * vmbus_request_addr - Returns the memory address stored at @trans_id

 * in @rqstor. Uses a spin lock to avoid race conditions.

 * @channel: Pointer to the VMbus channel struct

 * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's

 * next request id.

 */

u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)

{

	return vmbus_request_addr_match(channel, trans_id, VMBUS_RQST_ADDR_ANY);

}

EXPORT_SYMBOL_GPL(vmbus_request_addr);

include/linux/hyperv.h

+5 −0
Original line number Diff line number Diff line
@@ -788,6 +788,7 @@ struct vmbus_requestor { 


#define VMBUS_NO_RQSTOR U64_MAX

#define VMBUS_RQST_ERROR (U64_MAX - 1)

#define VMBUS_RQST_ADDR_ANY U64_MAX

/* NetVSC-specific */

#define VMBUS_RQST_ID_NO_RESPONSE (U64_MAX - 2)

/* StorVSC-specific */
@@ -1042,6 +1043,10 @@ struct vmbus_channel { 
};



u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr);

u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,

			       u64 rqst_addr);

u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,

			     u64 rqst_addr);

u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id);



static inline bool is_hvsock_channel(const struct vmbus_channel *c)