Re: [Xen-devel] [PATCH 3/5] kexec/xen: use libxc to get location of crash notes

Konrad Rzeszutek Wilk
2013-09-23T14:06:18Z

On Thu, Sep 12, 2013 at 09:00:40PM +0100, David Vrabel wrote:
> From: David Vrabel <david.vrabel@citrix.com>
>
> Use xc_kexec_get_range(KEXEC_RANGE_MA_CPU) instead of parsing
> /proc/iomem (which is only populated by non-upstream ("classic") Xen
> kernels).
>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> ---
> kexec/crashdump-xen.c | 67 +++++++++++++++++++++++++++++-------------------
> 1 files changed, 40 insertions(+), 27 deletions(-)
>
> diff --git a/kexec/crashdump-xen.c b/kexec/crashdump-xen.c
> index ff4706c..4a5cd8a 100644
> --- a/kexec/crashdump-xen.c
> +++ b/kexec/crashdump-xen.c
> @@ -163,42 +163,55 @@ unsigned long xen_architecture(struct crash_elf_info *elf_info)
> return machine;
> }
>
> -static int xen_crash_note_callback(void *UNUSED(data), int nr,
> - char *UNUSED(str),
> - unsigned long base,
> - unsigned long length)
> -{
> - struct crash_note_info *note = xen_phys_notes + nr;
> -
> - note->base = base;
> - note->length = length;
> -
> - return 0;
> -}
> -
> +#ifdef HAVE_LIBXENCTRL
> int xen_get_nr_phys_cpus(void)
> {
> - char *match = "Crash note\n";
> - int cpus, n;
> + xc_interface *xc;
> + int max_cpus;
> + int cpu;
>
> if (xen_phys_cpus)
> return xen_phys_cpus;
>
> - if ((cpus = kexec_iomem_for_each_line(match, NULL, NULL))) {
> - n = sizeof(struct crash_note_info) * cpus;
> - xen_phys_notes = malloc(n);
> - if (!xen_phys_notes) {
> - fprintf(stderr, "failed to allocate xen_phys_notes.\n");
> - return -1;
> - }
> - memset(xen_phys_notes, 0, n);
> - kexec_iomem_for_each_line(match,
> - xen_crash_note_callback, NULL);
> - xen_phys_cpus = cpus;
> + xc = xc_interface_open(NULL, NULL, 0);
> + if (!xc) {
> + fprintf(stderr, "failed to open xen control interface.\n");
> + return -1;
> + }
> +
> + max_cpus = xc_get_max_cpus(xc);
> + if (max_cpus <= 0)

Shouldn't you also call xc_interface_close ?

> + return -1;
> +
> + xen_phys_notes = calloc(max_cpus, sizeof(*xen_phys_notes));
> + if (xen_phys_notes == NULL)
> + return -1;

Ditto - call xc_interface_close?

> +
> + for (cpu = 0; cpu < max_cpus; cpu++) {
> + uint64_t size, start;
> + int ret;
> +
> + ret = xc_kexec_get_range(xc, KEXEC_RANGE_MA_CPU, cpu, &size, &start);
> + if (ret < 0)
> + break;
> +
> + xen_phys_notes[cpu].base = start;
> + xen_phys_notes[cpu].length = size;
> }
>
> - return cpus;
> + xc_interface_close(xc);
> +
> + xen_phys_cpus = cpu;
> +
> + return cpu;
> }
> +#else
> +int xen_get_nr_phys_cpus(void)
> +{
> + return -1;
> +}
> +#endif
> +
>
> int xen_get_note(int cpu, uint64_t *addr, uint64_t *len)
> {
> --
> 1.7.2.5
>
>
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