RE: [PATCH v3] scsi: storvsc: Removing Pre Win8 related logic

Michael Kelley (LINUX)
2022-05-24T15:04:58Z

From: Saurabh Sengar <ssengar@linux.microsoft.com>
>
> The latest storvsc code has already removed the support for windows 7 and
> earlier. There is still some code logic reamining which is there to support
> pre Windows 8 OS. This patch removes these stale logic.
> This patch majorly does three things :
>
> 1. Removes vmscsi_size_delta and its logic, as the vmscsi_request struct is
> same for all the OS post windows 8 there is no need of delta.
> 2. Simplify sense_buffer_size logic, as there is single buffer size for
> all the post windows 8 OS.
> 3. Embed the vmscsi_win8_extension structure inside the vmscsi_request,
> as there is no separate handling required for different OS.
>
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> ---
> v3 : Removed pre win8 macros:
> - POST_WIN7_STORVSC_SENSE_BUFFER_SIZE
> - VMSTOR_PROTO_VERSION_WIN6
> - VMSTOR_PROTO_VERSION_WIN7
>
> drivers/scsi/storvsc_drv.c | 152 ++++++++++---------------------------
> 1 file changed, 40 insertions(+), 112 deletions(-)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index 5585e9d30bbf..66d9adb5487f 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -55,8 +55,6 @@
> #define VMSTOR_PROTO_VERSION(MAJOR_, MINOR_) ((((MAJOR_) & 0xff) <<
> 8) | \
> (((MINOR_) & 0xff)))
>
> -#define VMSTOR_PROTO_VERSION_WIN6 VMSTOR_PROTO_VERSION(2, 0)
> -#define VMSTOR_PROTO_VERSION_WIN7 VMSTOR_PROTO_VERSION(4, 2)
> #define VMSTOR_PROTO_VERSION_WIN8 VMSTOR_PROTO_VERSION(5, 1)
> #define VMSTOR_PROTO_VERSION_WIN8_1 VMSTOR_PROTO_VERSION(6, 0)
> #define VMSTOR_PROTO_VERSION_WIN10 VMSTOR_PROTO_VERSION(6, 2)
> @@ -136,19 +134,15 @@ struct hv_fc_wwn_packet {
> */
> #define STORVSC_MAX_CMD_LEN 0x10
>
> -#define POST_WIN7_STORVSC_SENSE_BUFFER_SIZE 0x14
> -#define PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE 0x12
> -
> #define STORVSC_SENSE_BUFFER_SIZE 0x14
> #define STORVSC_MAX_BUF_LEN_WITH_PADDING 0x14
>
> /*
> - * Sense buffer size changed in win8; have a run-time
> - * variable to track the size we should use. This value will
> - * likely change during protocol negotiation but it is valid
> - * to start by assuming pre-Win8.
> + * Sense buffer size was differnt pre win8 but those OS are not supported any
> + * more starting 5.19 kernel. This results in to supporting a single value from
> + * win8 onwards.
> */
> -static int sense_buffer_size = PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE;
> +static int sense_buffer_size = STORVSC_SENSE_BUFFER_SIZE;

Can't the variable be eliminated entirely? The value doesn't ever change.
The variable is referenced in two places, and those two places could just
use the constant STORVSC_SENSE_BUFFER_SIZE.

Michael

>
> /*
> * The storage protocol version is determined during the
> @@ -177,18 +171,6 @@ do {
> \
> dev_warn(&(dev)->device, fmt, ##__VA_ARGS__); \
> } while (0)
>
> -struct vmscsi_win8_extension {
> - /*
> - * The following were added in Windows 8
> - */
> - u16 reserve;
> - u8 queue_tag;
> - u8 queue_action;
> - u32 srb_flags;
> - u32 time_out_value;
> - u32 queue_sort_ey;
> -} __packed;
> -
> struct vmscsi_request {
> u16 length;
> u8 srb_status;
> @@ -214,46 +196,23 @@ struct vmscsi_request {
> /*
> * The following was added in win8.
> */
> - struct vmscsi_win8_extension win8_extension;
> + u16 reserve;
> + u8 queue_tag;
> + u8 queue_action;
> + u32 srb_flags;
> + u32 time_out_value;
> + u32 queue_sort_ey;
>
> } __attribute((packed));
>
> /*
> - * The list of storage protocols in order of preference.
> + * The list of windows version in order of preference.
> */
> -struct vmstor_protocol {
> - int protocol_version;
> - int sense_buffer_size;
> - int vmscsi_size_delta;
> -};
> -
>
> -static const struct vmstor_protocol vmstor_protocols[] = {
> - {
> +static const int protocol_version[] = {
> VMSTOR_PROTO_VERSION_WIN10,
> - POST_WIN7_STORVSC_SENSE_BUFFER_SIZE,
> - 0
> - },
> - {
> VMSTOR_PROTO_VERSION_WIN8_1,
> - POST_WIN7_STORVSC_SENSE_BUFFER_SIZE,
> - 0
> - },
> - {
> VMSTOR_PROTO_VERSION_WIN8,
> - POST_WIN7_STORVSC_SENSE_BUFFER_SIZE,
> - 0
> - },
> - {
> - VMSTOR_PROTO_VERSION_WIN7,
> - PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE,
> - sizeof(struct vmscsi_win8_extension),
> - },
> - {
> - VMSTOR_PROTO_VERSION_WIN6,
> - PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE,
> - sizeof(struct vmscsi_win8_extension),
> - }
> };
>
>
> @@ -409,9 +368,7 @@ static void storvsc_on_channel_callback(void *context);
> #define STORVSC_IDE_MAX_CHANNELS 1
>
> /*
> - * Upper bound on the size of a storvsc packet. vmscsi_size_delta is not
> - * included in the calculation because it is set after STORVSC_MAX_PKT_SIZE
> - * is used in storvsc_connect_to_vsp
> + * Upper bound on the size of a storvsc packet.
> */
> #define STORVSC_MAX_PKT_SIZE (sizeof(struct vmpacket_descriptor) +\
> sizeof(struct vstor_packet))
> @@ -452,17 +409,6 @@ struct storvsc_device {
> unsigned char path_id;
> unsigned char target_id;
>
> - /*
> - * The size of the vmscsi_request has changed in win8. The
> - * additional size is because of new elements added to the
> - * structure. These elements are valid only when we are talking
> - * to a win8 host.
> - * Track the correction to size we need to apply. This value
> - * will likely change during protocol negotiation but it is
> - * valid to start by assuming pre-Win8.
> - */
> - int vmscsi_size_delta;
> -
> /*
> * Max I/O, the device can support.
> */
> @@ -795,8 +741,7 @@ static void handle_multichannel_storage(struct hv_device
> *device, int max_chns)
> vstor_packet->sub_channel_count = num_sc;
>
> ret = vmbus_sendpacket(device->channel, vstor_packet,
> - (sizeof(struct vstor_packet) -
> - stor_device->vmscsi_size_delta),
> + sizeof(struct vstor_packet),
> VMBUS_RQST_INIT,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> @@ -864,8 +809,7 @@ static int storvsc_execute_vstor_op(struct hv_device *device,
> vstor_packet->flags = REQUEST_COMPLETION_FLAG;
>
> ret = vmbus_sendpacket(device->channel, vstor_packet,
> - (sizeof(struct vstor_packet) -
> - stor_device->vmscsi_size_delta),
> + sizeof(struct vstor_packet),
> VMBUS_RQST_INIT,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> @@ -915,14 +859,13 @@ static int storvsc_channel_init(struct hv_device *device, bool
> is_fc)
> * Query host supported protocol version.
> */
>
> - for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {
> + for (i = 0; i < ARRAY_SIZE(protocol_version); i++) {
> /* reuse the packet for version range supported */
> memset(vstor_packet, 0, sizeof(struct vstor_packet));
> vstor_packet->operation =
> VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
>
> - vstor_packet->version.major_minor =
> - vmstor_protocols[i].protocol_version;
> + vstor_packet->version.major_minor = protocol_version[i];
>
> /*
> * The revision number is only used in Windows; set it to 0.
> @@ -936,21 +879,16 @@ static int storvsc_channel_init(struct hv_device *device, bool
> is_fc)
> return -EINVAL;
>
> if (vstor_packet->status == 0) {
> - vmstor_proto_version =
> - vmstor_protocols[i].protocol_version;
> -
> - sense_buffer_size =
> - vmstor_protocols[i].sense_buffer_size;
> -
> - stor_device->vmscsi_size_delta =
> - vmstor_protocols[i].vmscsi_size_delta;
> + vmstor_proto_version = protocol_version[i];
>
> break;
> }
> }
>
> - if (vstor_packet->status != 0)
> + if (vstor_packet->status != 0) {
> + dev_err(&device->device, "Obsolete Hyper-V version\n");
> return -EINVAL;
> + }
>
>
> memset(vstor_packet, 0, sizeof(struct vstor_packet));
> @@ -986,11 +924,10 @@ static int storvsc_channel_init(struct hv_device *device, bool
> is_fc)
> cpumask_set_cpu(device->channel->target_cpu,
> &stor_device->alloced_cpus);
>
> - if (vmstor_proto_version >= VMSTOR_PROTO_VERSION_WIN8) {
> - if (vstor_packet->storage_channel_properties.flags &
> - STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL)
> - process_sub_channels = true;
> - }
> + if (vstor_packet->storage_channel_properties.flags &
> + STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL)
> + process_sub_channels = true;
> +
> stor_device->max_transfer_bytes =
> vstor_packet->storage_channel_properties.max_transfer_bytes;
>
> @@ -1289,8 +1226,8 @@ static void storvsc_on_channel_callback(void *context)
> struct storvsc_cmd_request *request = NULL;
> u32 pktlen = hv_pkt_datalen(desc);
> u64 rqst_id = desc->trans_id;
> - u32 minlen = rqst_id ? sizeof(struct vstor_packet) -
> - stor_device->vmscsi_size_delta : sizeof(enum
> vstor_packet_operation);
> + u32 minlen = rqst_id ? sizeof(struct vstor_packet) :
> + sizeof(enum vstor_packet_operation);
>
> if (pktlen < minlen) {
> dev_err(&device->device,
> @@ -1346,7 +1283,7 @@ static void storvsc_on_channel_callback(void *context)
> }
>
> memcpy(&request->vstor_packet, packet,
> - (sizeof(struct vstor_packet) - stor_device->vmscsi_size_delta));
> + sizeof(struct vstor_packet));
> complete(&request->wait_event);
> }
> }
> @@ -1557,8 +1494,7 @@ static int storvsc_do_io(struct hv_device *device,
> found_channel:
> vstor_packet->flags |= REQUEST_COMPLETION_FLAG;
>
> - vstor_packet->vm_srb.length = (sizeof(struct vmscsi_request) -
> - stor_device->vmscsi_size_delta);
> + vstor_packet->vm_srb.length = sizeof(struct vmscsi_request);
>
>
> vstor_packet->vm_srb.sense_info_length = sense_buffer_size;
> @@ -1574,13 +1510,11 @@ static int storvsc_do_io(struct hv_device *device,
> ret = vmbus_sendpacket_mpb_desc(outgoing_channel,
> request->payload, request->payload_sz,
> vstor_packet,
> - (sizeof(struct vstor_packet) -
> - stor_device->vmscsi_size_delta),
> + sizeof(struct vstor_packet),
> (unsigned long)request);
> } else {
> ret = vmbus_sendpacket(outgoing_channel, vstor_packet,
> - (sizeof(struct vstor_packet) -
> - stor_device->vmscsi_size_delta),
> + sizeof(struct vstor_packet),
> (unsigned long)request,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> @@ -1684,8 +1618,7 @@ static int storvsc_host_reset_handler(struct scsi_cmnd
> *scmnd)
> vstor_packet->vm_srb.path_id = stor_device->path_id;
>
> ret = vmbus_sendpacket(device->channel, vstor_packet,
> - (sizeof(struct vstor_packet) -
> - stor_device->vmscsi_size_delta),
> + sizeof(struct vstor_packet),
> VMBUS_RQST_RESET,
> VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> @@ -1778,31 +1711,31 @@ static int storvsc_queuecommand(struct Scsi_Host *host,
> struct scsi_cmnd *scmnd)
>
> memset(&cmd_request->vstor_packet, 0, sizeof(struct vstor_packet));
> vm_srb = &cmd_request->vstor_packet.vm_srb;
> - vm_srb->win8_extension.time_out_value = 60;
> + vm_srb->time_out_value = 60;
>
> - vm_srb->win8_extension.srb_flags |=
> + vm_srb->srb_flags |=
> SRB_FLAGS_DISABLE_SYNCH_TRANSFER;
>
> if (scmnd->device->tagged_supported) {
> - vm_srb->win8_extension.srb_flags |=
> + vm_srb->srb_flags |=
> (SRB_FLAGS_QUEUE_ACTION_ENABLE |
> SRB_FLAGS_NO_QUEUE_FREEZE);
> - vm_srb->win8_extension.queue_tag = SP_UNTAGGED;
> - vm_srb->win8_extension.queue_action = SRB_SIMPLE_TAG_REQUEST;
> + vm_srb->queue_tag = SP_UNTAGGED;
> + vm_srb->queue_action = SRB_SIMPLE_TAG_REQUEST;
> }
>
> /* Build the SRB */
> switch (scmnd->sc_data_direction) {
> case DMA_TO_DEVICE:
> vm_srb->data_in = WRITE_TYPE;
> - vm_srb->win8_extension.srb_flags |= SRB_FLAGS_DATA_OUT;
> + vm_srb->srb_flags |= SRB_FLAGS_DATA_OUT;
> break;
> case DMA_FROM_DEVICE:
> vm_srb->data_in = READ_TYPE;
> - vm_srb->win8_extension.srb_flags |= SRB_FLAGS_DATA_IN;
> + vm_srb->srb_flags |= SRB_FLAGS_DATA_IN;
> break;
> case DMA_NONE:
> vm_srb->data_in = UNKNOWN_TYPE;
> - vm_srb->win8_extension.srb_flags |=
> SRB_FLAGS_NO_DATA_TRANSFER;
> + vm_srb->srb_flags |= SRB_FLAGS_NO_DATA_TRANSFER;
> break;
> default:
> /*
> @@ -2004,7 +1937,6 @@ static int storvsc_probe(struct hv_device *device,
> init_waitqueue_head(&stor_device->waiting_to_drain);
> stor_device->device = device;
> stor_device->host = host;
> - stor_device->vmscsi_size_delta = sizeof(struct vmscsi_win8_extension);
> spin_lock_init(&stor_device->lock);
> hv_set_drvdata(device, stor_device);
> dma_set_min_align_mask(&device->device, HV_HYP_PAGE_SIZE - 1);
> @@ -2217,10 +2149,6 @@ static int __init storvsc_drv_init(void)
> * than the ring buffer size since that page is reserved for
> * the ring buffer indices) by the max request size (which is
> * vmbus_channel_packet_multipage_buffer + struct vstor_packet + u64)
> - *
> - * The computation underestimates max_outstanding_req_per_channel
> - * for Win7 and older hosts because it does not take into account
> - * the vmscsi_size_delta correction to the max request size.
> */
> max_outstanding_req_per_channel =
> ((storvsc_ringbuffer_size - PAGE_SIZE) /
> --
> 2.25.1