Re: [Xen-devel] [PATCH 4/4] Implement 'xm vcpu-set' command for HVM guest

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-05-31 at 17:33 +0100, Anthony PERARD wrote:
> From: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> 
> Currently Xen has 'xm vcpu-set' command for PV domain, but not
> available for HVM domain.  This patch is use to enable 'xm vcpu-set'
> command for HVM domain. It setup vcpu watch at xenstore, and at qemu
> side, handle vcpu online/offline accordingly.  With this patch, 'xm
> vcpu-set' command works for both PV and HVM guest with same format.
> 
> Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> 
> Port from qemu-xen-traditionnal to qemu-xen:
>   qemu-xen does not support anymore command through xenstore, so this
>   path include an initialisation of a xenstore loop.
>   An upstream of this patch would need to go QMP.

Because of this forward port the title is inaccurate, since this doesn't
do anything for xm and only xl, right?

How much of the original patch is actually left?

BTW, for forward (or backward) ports including the original changeset ID
in the new comment is very useful.


> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> ---
>  hw/acpi_piix4.c |  5 +++--
>  xen-all.c       | 65 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 68 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/acpi_piix4.c b/hw/acpi_piix4.c
> index 49c38d3..4c01aa2 100644
> --- a/hw/acpi_piix4.c
> +++ b/hw/acpi_piix4.c
> @@ -728,8 +728,8 @@ static int disable_processor(PIIX4PMState *g, int cpu)
>  
>  void qemu_cpu_add_remove(int cpu, int state)
>  {
> -    if ((cpu <=0) || (cpu >= max_cpus)) {
> -        fprintf(stderr, "vcpu out of range, should be [1~%d]\n", max_cpus - 
> 1);
> +    if ((cpu < 0) || (cpu >= max_cpus)) {
> +        fprintf(stderr, "vcpu out of range, should be [0~%d]\n", max_cpus - 
> 1);
>          return;
>      }
>  
> @@ -742,6 +742,7 @@ void qemu_cpu_add_remove(int cpu, int state)
>              return;
>          }
>      }
> +    fprintf(stderr, "%s vcpu %d\n", state ? "Add" : "Remove", cpu);

Is this left over debugging?

>      pm_update_sci(acpi_state);
>  }
> diff --git a/xen-all.c b/xen-all.c
> index daf43b9..04b88a6 100644
> --- a/xen-all.c
> +++ b/xen-all.c
> @@ -99,6 +99,8 @@ typedef struct XenIOState {
>      Notifier suspend;
>  } XenIOState;
>  
> +static void xen_xenstore_watch_vcpu_set(XenIOState *state);
> +
>  /* Xen specific function for piix pci */
>  
>  int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num)
> @@ -1170,6 +1172,7 @@ int xen_hvm_init(void)
>      xen_be_register("vkbd", &xen_kbdmouse_ops);
>      xen_be_register("qdisk", &xen_blkdev_ops);
>      xen_read_physmap(state);
> +    xen_xenstore_watch_vcpu_set(state);
>  
>      return 0;
>  }
> @@ -1234,3 +1237,65 @@ void xen_modified_memory(ram_addr_t start, ram_addr_t 
> length)
>          }
>      }
>  }
> +
> +/* Xenstore watch init for vcpu-set */
> +
> +static void xenstore_process_vcpu_set_event(char **vec, struct xs_handle 
> *xsh)
> +{
> +    char *act = NULL;
> +    char *vcpustr, *node = vec[XS_WATCH_PATH];
> +    unsigned int vcpu, len;
> +
> +    vcpustr = strstr(node, "cpu/");
> +    if (!vcpustr) {
> +        fprintf(stderr, "vcpu-set: watch node error.\n");
> +        return;
> +    }
> +    sscanf(vcpustr, "cpu/%u", &vcpu);
> +
> +    act = xs_read(xsh, XBT_NULL, node, &len);
> +    if (!act) {
> +        fprintf(stderr, "vcpu-set: no command yet.\n");
> +        return;
> +    }
> +
> +    if (!strncmp(act, "online", len))
> +        qemu_cpu_add_remove(vcpu, 1);
> +    else if (!strncmp(act, "offline", len))
> +        qemu_cpu_add_remove(vcpu, 0);
> +    else
> +        fprintf(stderr, "vcpu-set: command error.\n");
> +
> +    free(act);
> +    return;
> +}
> +
> +static void xenstore_process_event(void *opaque)
> +{
> +    char **vec;
> +    unsigned int num;
> +    struct xs_handle *xsh = opaque;
> +
> +    vec = xs_read_watch(xsh, &num);
> +    if (!vec)
> +        return;
> +
> +    if (!strcmp(vec[XS_WATCH_TOKEN], "vcpu-set")) {
> +        xenstore_process_vcpu_set_event(vec, xsh);
> +        goto out;
> +    }
> +
> + out:
> +    free(vec);
> +}
> +
> +static void xen_xenstore_watch_vcpu_set(XenIOState *state)
> +{
> +    char path[40];
> +    /* Set a watch for vcpu-set */
> +    snprintf(path, sizeof(path), "/local/domain/%d/cpu", xen_domid);
> +    xs_watch(state->xenstore, path, "vcpu-set");
> +
> +    qemu_set_fd_handler(xs_fileno(state->xenstore), xenstore_process_event,
> +                        NULL, state->xenstore);
> +}



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