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Date: Mon, 19 Feb 2024 01:24:21 -0800
From: Saurabh Singh Sengar <ssengar@linux.microsoft.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
	decui@microsoft.com, linux-hyperv@vger.kernel.org,
	linux-kernel@vger.kernel.org, ssengar@microsoft.com
Subject: Re: [PATCH 5/6] tools: hv: Add new fcopy application based on uio
 driver
Message-ID: <20240219092421.GA32526@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
References: <1708193020-14740-1-git-send-email-ssengar@linux.microsoft.com>
 <1708193020-14740-6-git-send-email-ssengar@linux.microsoft.com>
 <2024021908-royal-sequester-84be@gregkh>
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In-Reply-To: <2024021908-royal-sequester-84be@gregkh>
User-Agent: Mutt/1.5.21 (2010-09-15)

On Mon, Feb 19, 2024 at 09:53:01AM +0100, Greg KH wrote:
> On Sat, Feb 17, 2024 at 10:03:39AM -0800, Saurabh Sengar wrote:
> > New fcopy application which utilizes uio_hv_vmbus_client driver
> 
> What does this "application" do?

I will improve the commit message with more information.

> 
> > 
> > Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> > ---
> >  tools/hv/Build                 |   3 +-
> >  tools/hv/Makefile              |  10 +-
> >  tools/hv/hv_fcopy_uio_daemon.c | 488 +++++++++++++++++++++++++++++++++
> >  3 files changed, 495 insertions(+), 6 deletions(-)
> >  create mode 100644 tools/hv/hv_fcopy_uio_daemon.c
> > 
> > diff --git a/tools/hv/Build b/tools/hv/Build
> > index 6cf51fa4b306..7d1f1698069b 100644
> > --- a/tools/hv/Build
> > +++ b/tools/hv/Build
> > @@ -1,3 +1,4 @@
> >  hv_kvp_daemon-y += hv_kvp_daemon.o
> >  hv_vss_daemon-y += hv_vss_daemon.o
> > -hv_fcopy_daemon-y += hv_fcopy_daemon.o
> > +hv_fcopy_uio_daemon-y += hv_fcopy_uio_daemon.o
> > +hv_fcopy_uio_daemon-y += vmbus_bufring.o
> > diff --git a/tools/hv/Makefile b/tools/hv/Makefile
> > index fe770e679ae8..944180cf916e 100644
> > --- a/tools/hv/Makefile
> > +++ b/tools/hv/Makefile
> > @@ -17,7 +17,7 @@ MAKEFLAGS += -r
> >  
> >  override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
> >  
> > -ALL_TARGETS := hv_kvp_daemon hv_vss_daemon hv_fcopy_daemon
> > +ALL_TARGETS := hv_kvp_daemon hv_vss_daemon hv_fcopy_uio_daemon
> >  ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))
> >  
> >  ALL_SCRIPTS := hv_get_dhcp_info.sh hv_get_dns_info.sh hv_set_ifconfig.sh
> > @@ -39,10 +39,10 @@ $(HV_VSS_DAEMON_IN): FORCE
> >  $(OUTPUT)hv_vss_daemon: $(HV_VSS_DAEMON_IN)
> >  	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
> >  
> > -HV_FCOPY_DAEMON_IN := $(OUTPUT)hv_fcopy_daemon-in.o
> > -$(HV_FCOPY_DAEMON_IN): FORCE
> > -	$(Q)$(MAKE) $(build)=hv_fcopy_daemon
> > -$(OUTPUT)hv_fcopy_daemon: $(HV_FCOPY_DAEMON_IN)
> > +HV_FCOPY_UIO_DAEMON_IN := $(OUTPUT)hv_fcopy_uio_daemon-in.o
> > +$(HV_FCOPY_UIO_DAEMON_IN): FORCE
> > +	$(Q)$(MAKE) $(build)=hv_fcopy_uio_daemon
> > +$(OUTPUT)hv_fcopy_uio_daemon: $(HV_FCOPY_UIO_DAEMON_IN)
> >  	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
> >  
> >  clean:
> > diff --git a/tools/hv/hv_fcopy_uio_daemon.c b/tools/hv/hv_fcopy_uio_daemon.c
> > new file mode 100644
> > index 000000000000..f72c899328fc
> > --- /dev/null
> > +++ b/tools/hv/hv_fcopy_uio_daemon.c
> > @@ -0,0 +1,488 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * An implementation of host to guest copy functionality for Linux.
> 
> host to guest of what?  I think it's a specific type of host and guest,
> right?

This application is replacement of hv_fcopy_daemon, so copied the exact
comment here. This is specific to Hyper-V host, I can add these details.


> 
> > + *
> > + * Copyright (C) 2023, Microsoft, Inc.
> > + *
> > + * Author : K. Y. Srinivasan <kys@microsoft.com>
> > + * Author : Saurabh Sengar <ssengar@microsoft.com>
> > + *
> > + */
> > +
> > +#include <dirent.h>
> > +#include <errno.h>
> > +#include <fcntl.h>
> > +#include <getopt.h>
> > +#include <locale.h>
> > +#include <stdbool.h>
> > +#include <stddef.h>
> > +#include <stdint.h>
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <syslog.h>
> > +#include <unistd.h>
> > +#include <wchar.h>
> > +#include <sys/stat.h>
> > +#include <linux/hyperv.h>
> > +#include <linux/limits.h>
> > +#include "vmbus_bufring.h"
> > +
> > +#define ICMSGTYPE_NEGOTIATE	0
> > +#define ICMSGTYPE_FCOPY		7
> > +
> > +#define WIN8_SRV_MAJOR		1
> > +#define WIN8_SRV_MINOR		1
> > +#define WIN8_SRV_VERSION	(WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
> > +
> > +#define MAX_FOLDER_NAME		15
> > +#define MAX_PATH_LEN		15
> > +#define FCOPY_UIO		"/sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/uio"
> > +
> > +#define FCOPY_VER_COUNT		1
> > +static const int fcopy_versions[] = {
> > +	WIN8_SRV_VERSION
> > +};
> > +
> > +#define FW_VER_COUNT		1
> > +static const int fw_versions[] = {
> > +	UTIL_FW_VERSION
> > +};
> > +
> > +#define HV_RING_SIZE		(4 * 4096)
> 
> Hey, that doesn't match the kernel driver!  Why these values?

This application talks to device which is recognize as HV_FCOPY
is kernel. In the first patch of current patch series I have
mentioned .pref_ring_size = 0x4000 for HV_FCOPY which matches this.

This code is well tested.


> 
> 
> > +
> > +unsigned char desc[HV_RING_SIZE];
> > +
> > +static int target_fd;
> > +static char target_fname[PATH_MAX];
> > +static unsigned long long filesize;
> > +
> > +static int hv_fcopy_create_file(char *file_name, char *path_name, __u32 flags)
> > +{
> > +	int error = HV_E_FAIL;
> > +	char *q, *p;
> > +
> > +	filesize = 0;
> > +	p = (char *)path_name;
> 
> Why the unneeded cast?

This code is existing today as form of hv_fcopy_daemon. As this new
application is replacing hv_fcopy_daemon I reused the same code and
casting.

But, I agree I can improve these.

> 
> > +	snprintf(target_fname, sizeof(target_fname), "%s/%s",
> > +		 (char *)path_name, (char *)file_name);
> 
> Again, why all of the unneeded casts?  This feels very odd, so I've
> stopped reading here, perhaps get an internal review first before
> sending this out again?

This patch has gone through extensive review in past, here is the
reference to the history:

https://lore.kernel.org/lkml/1691132996-11706-4-git-send-email-ssengar@linux.microsoft.com/

I will look for some more internal review and reviewed-by.

- Saurabh

> 
> thanks,
> 
> greg k-h