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Date:   Tue, 24 May 2022 08:14:39 -0700
From:   Saurabh Singh Sengar <ssengar@linux.microsoft.com>
To:     "Michael Kelley (LINUX)" <mikelley@microsoft.com>
Cc:     Saurabh Singh Sengar <ssengar@microsoft.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>,
        Dexuan Cui <decui@microsoft.com>,
        "jejb@linux.ibm.com" <jejb@linux.ibm.com>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        Long Li <longli@microsoft.com>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] scsi: storvsc: Removing Pre Win8 related logic
Message-ID: <20220524151439.GB7036@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
References: <1653392516-9233-1-git-send-email-ssengar@linux.microsoft.com>
 <PH0PR21MB30251F55B1617F48E11EE65DD7D79@PH0PR21MB3025.namprd21.prod.outlook.com>
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On Tue, May 24, 2022 at 03:04:50PM +0000, Michael Kelley (LINUX) wrote:
> 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
[sss] make sense, will do
> 
> > 
> >  /*
> >   * 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