RE: [PATCH hyperv-next] scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs

From: Michael Kelley
Date: Thu Apr 15 2021 - 09:22:40 EST

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In reply to: Andrea Parri (Microsoft): "[PATCH hyperv-next] scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs"
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From: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx> Sent: Thursday, April 15, 2021 3:59 AM
>
> Use blk_mq_unique_tag() to generate requestIDs for StorVSC, avoiding
> all issues with allocating enough entries in the VMbus requestor.
>
> Suggested-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
> ---
> Changes since RFC:
> - pass sentinel values for {init,reset}_request in vmbus_sendpacket()
> - remove/inline the storvsc_request_addr() callback
> - make storvsc_next_request_id() 'static'
> - add code to handle the case of an unsolicited message from Hyper-V
> - other minor/style changes
>
> [1] https://lore.kernel.org/linux-hyperv/20210408161315.341888-1-parri.andrea@xxxxxxxxx/
>
> drivers/hv/channel.c | 14 ++---
> drivers/hv/ring_buffer.c | 13 +++--
> drivers/net/hyperv/netvsc.c | 8 ++-
> drivers/net/hyperv/rndis_filter.c | 2 +
> drivers/scsi/storvsc_drv.c | 94 +++++++++++++++++++++----------
> include/linux/hyperv.h | 13 ++++-
> 6 files changed, 95 insertions(+), 49 deletions(-)

LGTM

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>

>
> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
> index db30be8f9ccea..f78e02ace51e8 100644
> --- a/drivers/hv/channel.c
> +++ b/drivers/hv/channel.c
> @@ -1121,15 +1121,14 @@ EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
> * vmbus_next_request_id - Returns a new request id. It is also
> * the index at which the guest memory address is stored.
> * Uses a spin lock to avoid race conditions.
> - * @rqstor: Pointer to the requestor struct
> + * @channel: Pointer to the VMbus channel struct
> * @rqst_add: Guest memory address to be stored in the array
> */
> -u64 vmbus_next_request_id(struct vmbus_requestor *rqstor, u64 rqst_addr)
> +u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
> {
> + struct vmbus_requestor *rqstor = &channel->requestor;
> unsigned long flags;
> u64 current_id;
> - const struct vmbus_channel *channel =
> - container_of(rqstor, const struct vmbus_channel, requestor);
>
> /* Check rqstor has been initialized */
> if (!channel->rqstor_size)
> @@ -1163,16 +1162,15 @@ 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.
> - * @rqstor: Pointer to the requestor struct
> + * @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_requestor *rqstor, u64 trans_id)
> +u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
> {
> + struct vmbus_requestor *rqstor = &channel->requestor;
> unsigned long flags;
> u64 req_addr;
> - const struct vmbus_channel *channel =
> - container_of(rqstor, const struct vmbus_channel, requestor);
>
> /* Check rqstor has been initialized */
> if (!channel->rqstor_size)
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> index ecd82ebfd5bc4..2bf57677272b5 100644
> --- a/drivers/hv/ring_buffer.c
> +++ b/drivers/hv/ring_buffer.c
> @@ -310,10 +310,12 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
> */
>
> if (desc->flags == VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED) {
> - rqst_id = vmbus_next_request_id(&channel->requestor, requestid);
> - if (rqst_id == VMBUS_RQST_ERROR) {
> - spin_unlock_irqrestore(&outring_info->ring_lock, flags);
> - return -EAGAIN;
> + if (channel->next_request_id_callback != NULL) {
> + rqst_id = channel->next_request_id_callback(channel, requestid);
> + if (rqst_id == VMBUS_RQST_ERROR) {
> + spin_unlock_irqrestore(&outring_info->ring_lock, flags);
> + return -EAGAIN;
> + }
> }
> }
> desc = hv_get_ring_buffer(outring_info) + old_write;
> @@ -341,7 +343,8 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
> if (channel->rescind) {
> if (rqst_id != VMBUS_NO_RQSTOR) {
> /* Reclaim request ID to avoid leak of IDs */
> - vmbus_request_addr(&channel->requestor, rqst_id);
> + if (channel->request_addr_callback != NULL)
> + channel->request_addr_callback(channel, rqst_id);
> }
> return -ENODEV;
> }
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index c64cc7639c39c..1a221ce2d6fdc 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -730,7 +730,7 @@ static void netvsc_send_tx_complete(struct net_device *ndev,
> int queue_sends;
> u64 cmd_rqst;
>
> - cmd_rqst = vmbus_request_addr(&channel->requestor, (u64)desc->trans_id);
> + cmd_rqst = channel->request_addr_callback(channel, (u64)desc->trans_id);
> if (cmd_rqst == VMBUS_RQST_ERROR) {
> netdev_err(ndev, "Incorrect transaction id\n");
> return;
> @@ -790,8 +790,8 @@ static void netvsc_send_completion(struct net_device *ndev,
>
> /* First check if this is a VMBUS completion without data payload */
> if (!msglen) {
> - cmd_rqst = vmbus_request_addr(&incoming_channel->requestor,
> - (u64)desc->trans_id);
> + cmd_rqst = incoming_channel->request_addr_callback(incoming_channel,
> + (u64)desc->trans_id);
> if (cmd_rqst == VMBUS_RQST_ERROR) {
> netdev_err(ndev, "Invalid transaction id\n");
> return;
> @@ -1602,6 +1602,8 @@ struct netvsc_device *netvsc_device_add(struct hv_device
> *device,
> netvsc_poll, NAPI_POLL_WEIGHT);
>
> /* Open the channel */
> + device->channel->next_request_id_callback = vmbus_next_request_id;
> + device->channel->request_addr_callback = vmbus_request_addr;
> device->channel->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
> ret = vmbus_open(device->channel, netvsc_ring_bytes,
> netvsc_ring_bytes, NULL, 0,
> diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
> index 123cc9d25f5ed..ebf34bf3f9075 100644
> --- a/drivers/net/hyperv/rndis_filter.c
> +++ b/drivers/net/hyperv/rndis_filter.c
> @@ -1259,6 +1259,8 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
> /* Set the channel before opening.*/
> nvchan->channel = new_sc;
>
> + new_sc->next_request_id_callback = vmbus_next_request_id;
> + new_sc->request_addr_callback = vmbus_request_addr;
> new_sc->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
> ret = vmbus_open(new_sc, netvsc_ring_bytes,
> netvsc_ring_bytes, NULL, 0,
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index 6bc5453cea8a7..b219a266cca80 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -684,6 +684,23 @@ static void storvsc_change_target_cpu(struct vmbus_channel
> *channel, u32 old,
> spin_unlock_irqrestore(&stor_device->lock, flags);
> }
>
> +static u64 storvsc_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
> +{
> + struct storvsc_cmd_request *request =
> + (struct storvsc_cmd_request *)(unsigned long)rqst_addr;
> +
> + if (rqst_addr == VMBUS_RQST_INIT)
> + return VMBUS_RQST_INIT;
> + if (rqst_addr == VMBUS_RQST_RESET)
> + return VMBUS_RQST_RESET;
> +
> + /*
> + * Cannot return an ID of 0, which is reserved for an unsolicited
> + * message from Hyper-V.
> + */
> + return (u64)blk_mq_unique_tag(request->cmd->request) + 1;
> +}
> +
> static void handle_sc_creation(struct vmbus_channel *new_sc)
> {
> struct hv_device *device = new_sc->primary_channel->device_obj;
> @@ -698,11 +715,7 @@ static void handle_sc_creation(struct vmbus_channel *new_sc)
>
> memset(&props, 0, sizeof(struct vmstorage_channel_properties));
>
> - /*
> - * The size of vmbus_requestor is an upper bound on the number of requests
> - * that can be in-progress at any one time across all channels.
> - */
> - new_sc->rqstor_size = scsi_driver.can_queue;
> + new_sc->next_request_id_callback = storvsc_next_request_id;
>
> ret = vmbus_open(new_sc,
> storvsc_ringbuffer_size,
> @@ -769,7 +782,7 @@ static void handle_multichannel_storage(struct hv_device *device,
> int max_chns)
> ret = vmbus_sendpacket(device->channel, vstor_packet,
> (sizeof(struct vstor_packet) -
> stor_device->vmscsi_size_delta),
> - (unsigned long)request,
> + VMBUS_RQST_INIT,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
>
> @@ -838,7 +851,7 @@ static int storvsc_execute_vstor_op(struct hv_device *device,
> ret = vmbus_sendpacket(device->channel, vstor_packet,
> (sizeof(struct vstor_packet) -
> stor_device->vmscsi_size_delta),
> - (unsigned long)request,
> + VMBUS_RQST_INIT,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> if (ret != 0)
> @@ -1240,6 +1253,7 @@ static void storvsc_on_channel_callback(void *context)
> const struct vmpacket_descriptor *desc;
> struct hv_device *device;
> struct storvsc_device *stor_device;
> + struct Scsi_Host *shost;
>
> if (channel->primary_channel != NULL)
> device = channel->primary_channel->device_obj;
> @@ -1250,20 +1264,12 @@ static void storvsc_on_channel_callback(void *context)
> if (!stor_device)
> return;
>
> - foreach_vmbus_pkt(desc, channel) {
> - void *packet = hv_pkt_data(desc);
> - struct storvsc_cmd_request *request;
> - u64 cmd_rqst;
> -
> - cmd_rqst = vmbus_request_addr(&channel->requestor,
> - desc->trans_id);
> - if (cmd_rqst == VMBUS_RQST_ERROR) {
> - dev_err(&device->device,
> - "Incorrect transaction id\n");
> - continue;
> - }
> + shost = stor_device->host;
>
> - request = (struct storvsc_cmd_request *)(unsigned long)cmd_rqst;
> + foreach_vmbus_pkt(desc, channel) {
> + struct vstor_packet *packet = hv_pkt_data(desc);
> + struct storvsc_cmd_request *request = NULL;
> + u64 rqst_id = desc->trans_id;
>
> if (hv_pkt_datalen(desc) < sizeof(struct vstor_packet) -
> stor_device->vmscsi_size_delta) {
> @@ -1271,14 +1277,44 @@ static void storvsc_on_channel_callback(void *context)
> continue;
> }
>
> - if (request == &stor_device->init_request ||
> - request == &stor_device->reset_request) {
> - memcpy(&request->vstor_packet, packet,
> - (sizeof(struct vstor_packet) - stor_device->vmscsi_size_delta));
> - complete(&request->wait_event);
> + if (rqst_id == VMBUS_RQST_INIT) {
> + request = &stor_device->init_request;
> + } else if (rqst_id == VMBUS_RQST_RESET) {
> + request = &stor_device->reset_request;
> } else {
> + /* Hyper-V can send an unsolicited message with ID of 0 */
> + if (rqst_id == 0) {
> + /*
> + * storvsc_on_receive() looks at the vstor_packet in the
> message
> + * from the ring buffer. If the operation in the vstor_packet
> is
> + * COMPLETE_IO, then we call storvsc_on_io_completion(),
> and
> + * dereference the guest memory address. Make sure we
> don't call
> + * storvsc_on_io_completion() with a guest memory
> address that is
> + * zero if Hyper-V were to construct and send such a bogus
> packet.
> + */
> + if (packet->operation ==
> VSTOR_OPERATION_COMPLETE_IO) {
> + dev_err(&device->device, "Invalid packet with ID of
> 0\n");
> + continue;
> + }
> + } else {
> + struct scsi_cmnd *scmnd;
> +
> + /* Transaction 'rqst_id' corresponds to tag 'rqst_id - 1' */
> + scmnd = scsi_host_find_tag(shost, rqst_id - 1);
> + if (scmnd == NULL) {
> + dev_err(&device->device, "Incorrect transaction
> ID\n");
> + continue;
> + }
> + request = (struct storvsc_cmd_request
> *)scsi_cmd_priv(scmnd);
> + }
> +
> storvsc_on_receive(stor_device, packet, request);
> + continue;
> }
> +
> + memcpy(&request->vstor_packet, packet,
> + (sizeof(struct vstor_packet) - stor_device->vmscsi_size_delta));
> + complete(&request->wait_event);
> }
> }
>
> @@ -1290,11 +1326,7 @@ static int storvsc_connect_to_vsp(struct hv_device *device, u32
> ring_size,
>
> memset(&props, 0, sizeof(struct vmstorage_channel_properties));
>
> - /*
> - * The size of vmbus_requestor is an upper bound on the number of requests
> - * that can be in-progress at any one time across all channels.
> - */
> - device->channel->rqstor_size = scsi_driver.can_queue;
> + device->channel->next_request_id_callback = storvsc_next_request_id;
>
> ret = vmbus_open(device->channel,
> ring_size,
> @@ -1620,7 +1652,7 @@ static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
> ret = vmbus_sendpacket(device->channel, vstor_packet,
> (sizeof(struct vstor_packet) -
> stor_device->vmscsi_size_delta),
> - (unsigned long)&stor_device->reset_request,
> + VMBUS_RQST_RESET,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> if (ret != 0)
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index 2c18c8e768efe..5692ffa60e022 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -779,7 +779,11 @@ struct vmbus_requestor {
>
> #define VMBUS_NO_RQSTOR U64_MAX
> #define VMBUS_RQST_ERROR (U64_MAX - 1)
> +/* NetVSC-specific */
> #define VMBUS_RQST_ID_NO_RESPONSE (U64_MAX - 2)
> +/* StorVSC-specific */
> +#define VMBUS_RQST_INIT (U64_MAX - 2)
> +#define VMBUS_RQST_RESET (U64_MAX - 3)
>
> struct vmbus_device {
> u16 dev_type;
> @@ -1007,13 +1011,18 @@ struct vmbus_channel {
> u32 fuzz_testing_interrupt_delay;
> u32 fuzz_testing_message_delay;
>
> + /* callback to generate a request ID from a request address */
> + u64 (*next_request_id_callback)(struct vmbus_channel *channel, u64 rqst_addr);
> + /* callback to retrieve a request address from a request ID */
> + u64 (*request_addr_callback)(struct vmbus_channel *channel, u64 rqst_id);
> +
> /* request/transaction ids for VMBus */
> struct vmbus_requestor requestor;
> u32 rqstor_size;
> };
>
> -u64 vmbus_next_request_id(struct vmbus_requestor *rqstor, u64 rqst_addr);
> -u64 vmbus_request_addr(struct vmbus_requestor *rqstor, u64 trans_id);
> +u64 vmbus_next_request_id(struct vmbus_channel *channel, 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)
> {
> --
> 2.25.1

Next message: Daniel Bristot de Oliveira: "Re: [RFC PATCH 3/5] tracing/hwlat: Implement the per-cpu mode"
Previous message: Willy Tarreau: "Re: [PATCH] floppy: remove redundant assignment to variable st"
In reply to: Andrea Parri (Microsoft): "[PATCH hyperv-next] scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs"
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