Re: [PATCH v2] scsi: storvsc: Removing Pre Win8 related logic

From: Saurabh Singh Sengar
Date: Tue May 24 2022 - 00:48:57 EST

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On Tue, May 24, 2022 at 01:02:24AM +0000, Michael Kelley (LINUX) wrote:
> From: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxxxxxxx>
> > ---
> > v2 : 1. Added error message for old Hyper-V versions
> > 2. Removed a check "vmstor_proto_version >= VMSTOR_PROTO_VERSION_WIN8",
> > which will always be true
> >
> > drivers/scsi/storvsc_drv.c | 148 ++++++++++---------------------------
> > 1 file changed, 40 insertions(+), 108 deletions(-)
> >
> > diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> > index 5585e9d30bbf..dd9cde6331bc 100644
> > --- a/drivers/scsi/storvsc_drv.c
> > +++ b/drivers/scsi/storvsc_drv.c
> > @@ -137,18 +137,16 @@ 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 = POST_WIN7_STORVSC_SENSE_BUFFER_SIZE;
>
> I think you could remove the sense_buffer_size variable
> as well as POST_WIN7_STORVSC_SENSE_BUFFER_SIZE. Just
> use STORVSC_SENSE_BUFFER_SIZE in the two places still left
> where the variable is used.
>
> Michael

[SS] : Sure, I think we can remove below macros as well. will fix in v3.

#define VMSTOR_PROTO_VERSION_WIN6 VMSTOR_PROTO_VERSION(2, 0)
#define VMSTOR_PROTO_VERSION_WIN7 VMSTOR_PROTO_VERSION(4, 2)

>
> >
> > /*
> > * The storage protocol version is determined during the
> > @@ -177,18 +175,6 @@ 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 +200,23 @@ 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 +372,7 @@ 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 +413,6 @@ 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 +745,7 @@ 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 +813,7 @@ 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 +863,13 @@ 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 +883,16 @@ 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 +928,10 @@ 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 +1230,8 @@ 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 +1287,7 @@ 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 +1498,7 @@ 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 +1514,11 @@ 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 +1622,7 @@ 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 +1715,31 @@ 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 +1941,6 @@ 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 +2153,6 @@ 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

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