Re: [PATCH RFC 14/14] xen: tools: Added xen-subpage tool.

From: Razvan Cojocaru <rcojocaru@bitdefender.com>
To: Zhang Yi <yi.z.zhang@linux.intel.com>, xen-devel@lists.xenproject.org
Cc: kevin.tian@intel.com, tamas@tklengyel.com, wei.liu2@citrix.com,
	jun.nakajima@intel.com, george.dunlap@eu.citrix.com,
	andrew.cooper3@citrix.com, ian.jackson@eu.citrix.com,
	jbeulich@suse.com
Subject: Re: [PATCH RFC 14/14] xen: tools: Added xen-subpage tool.
Date: Thu, 19 Oct 2017 11:42:17 +0300	[thread overview]
Message-ID: <9d839e5c-b3b4-8dc1-8378-a937fee45e95@bitdefender.com> (raw)
In-Reply-To: <90cbda6aa45b0de7e16b685af9b64e2973a139ba.1508397860.git.yi.z.zhang@linux.intel.com>

> +#include <errno.h>
> +#include <inttypes.h>
> +#include <stdlib.h>
> +#include <stdarg.h>
> +#include <stdbool.h>
> +#include <string.h>
> +#include <time.h>
> +#include <signal.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +#include <poll.h>
> +
> +#include <xenctrl.h>
> +
> +#define DPRINTF(a, b...) fprintf(stderr, a, ## b)
> +#define ERROR(a, b...) fprintf(stderr, a "\n", ## b)
> +#define PERROR(a, b...) fprintf(stderr, a ": %s\n", ## b, strerror(errno))
> +
> +void usage(char* progname)
> +{
> +    fprintf(stderr, "Usage: %s [-m] <domain_id> get|set [gfn] [bit_map]", progname);
> +
> +            fprintf(stderr,
> +            "\n"
> +            "set - set gfn bitmap.\n"
> +            "\n"
> +            "-m requires this program to run\n");
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +    domid_t domain_id;
> +    xc_interface *xch;
> +    xen_pfn_t gfn = 0;
> +    uint32_t access = 0;
> +    int required = 0;
> +    int rc = 0;
> +
> +    char* progname = argv[0];
> +    argv++;
> +    argc--;
> +
> +    if ( argc == 5 && argv[0][0] == '-' )
> +    {
> +        if ( !strcmp(argv[0], "-m") )
> +            required = 1;
> +        else
> +        {
> +            usage(progname);
> +            return -1;
> +        }
> +        argv++;
> +        argc--;
> +    }
> +
> +    if ( argc != 4 )
> +    {
> +        usage(progname);
> +        return -1;
> +    }
> +
> +    domain_id = atoi(argv[0]);
> +    argv++;
> +    argc--;
> +
> +    if ( !strcmp(argv[0], "set") )
> +    {
> +        gfn = strtoul(argv[1], 0, 0);
> +        access = strtoul(argv[2], 0, 0);
> +        DPRINTF("set subpage gfn:0x%lx -- map:0x%x\n", gfn, access);
> +        xch = xc_interface_open(NULL, NULL, 0);
> +        if ( !xch )
> +        {
> +            ERROR("get interface error\n");
> +            return -1;
> +        }
> +        xc_mem_set_subpage(xch, domain_id, gfn, access);
> +        xc_interface_close(xch);
> +    }
> +    else
> +    {
> +        usage(argv[0]);
> +        return -1;
> +    }
> +
> +    return rc;
> +}

As far as I understand, this example just calls the new hypercall and exits.

Should there be another vm_event-subscribed application that will be
affected by the changes? If so, doesn't this rather belong in the
xen-access.c test?

Also, no explanation is given in comments in the source code or the
displayed help for useful values of the access parameter, and what it
stands for.

Thanks,
Razvan

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