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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [XEN PATCH v2 5/5] tools: add example application to initialize dom0less PV drivers
Hi Stefano,
> On 13 Jan 2022, at 00:58, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote:
>
> From: Luca Miccio <lucmiccio@xxxxxxxxx>
>
> Add an example application that can be run in dom0 to complete the
> dom0less domains initialization so that they can get access to xenstore
> and use PV drivers.
>
> Signed-off-by: Luca Miccio <lucmiccio@xxxxxxxxx>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
> CC: Wei Liu <wl@xxxxxxx>
> CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> CC: Juergen Gross <jgross@xxxxxxxx>
> ---
> Changes in v2:
> - do not set HVM_PARAM_STORE_EVTCHN twice
> - rename restore_xenstore to create_xenstore
> - increase maxmem
> ---
> tools/helpers/Makefile | 13 ++
> tools/helpers/init-dom0less.c | 266 ++++++++++++++++++++++++++++++++++
> 2 files changed, 279 insertions(+)
> create mode 100644 tools/helpers/init-dom0less.c
>
> diff --git a/tools/helpers/Makefile b/tools/helpers/Makefile
> index 7f6c422440..8e42997052 100644
> --- a/tools/helpers/Makefile
> +++ b/tools/helpers/Makefile
> @@ -10,6 +10,9 @@ ifeq ($(CONFIG_Linux),y)
> ifeq ($(CONFIG_X86),y)
> PROGS += init-xenstore-domain
> endif
> +ifeq ($(CONFIG_ARM),y)
> +PROGS += init-dom0less
> +endif
> endif
>
> XEN_INIT_DOM0_OBJS = xen-init-dom0.o init-dom-json.o
> @@ -26,6 +29,13 @@ $(INIT_XENSTORE_DOMAIN_OBJS): CFLAGS +=
> $(CFLAGS_libxenstore)
> $(INIT_XENSTORE_DOMAIN_OBJS): CFLAGS += $(CFLAGS_libxenlight)
> $(INIT_XENSTORE_DOMAIN_OBJS): CFLAGS += -include $(XEN_ROOT)/tools/config.h
>
> +INIT_DOM0LESS_OBJS = init-dom0less.o init-dom-json.o
> +$(INIT_DOM0LESS_OBJS): CFLAGS += $(CFLAGS_libxentoollog)
> +$(INIT_DOM0LESS_OBJS): CFLAGS += $(CFLAGS_libxenstore)
> +$(INIT_DOM0LESS_OBJS): CFLAGS += $(CFLAGS_libxenlight)
> +$(INIT_DOM0LESS_OBJS): CFLAGS += $(CFLAGS_libxenctrl)
> +$(INIT_DOM0LESS_OBJS): CFLAGS += $(CFLAGS_libxenevtchn)
> +
> .PHONY: all
> all: $(PROGS)
>
> @@ -35,6 +45,9 @@ xen-init-dom0: $(XEN_INIT_DOM0_OBJS)
> init-xenstore-domain: $(INIT_XENSTORE_DOMAIN_OBJS)
> $(CC) $(LDFLAGS) -o $@ $(INIT_XENSTORE_DOMAIN_OBJS)
> $(LDLIBS_libxentoollog) $(LDLIBS_libxenstore) $(LDLIBS_libxenctrl)
> $(LDLIBS_libxenguest) $(LDLIBS_libxenlight) $(APPEND_LDFLAGS)
>
> +init-dom0less: $(INIT_DOM0LESS_OBJS)
> + $(CC) $(LDFLAGS) -o $@ $(INIT_DOM0LESS_OBJS) $(LDLIBS_libxenctrl)
> $(LDLIBS_libxenevtchn) $(LDLIBS_libxentoollog) $(LDLIBS_libxenstore)
> $(LDLIBS_libxenlight) $(LDLIBS_libxenguest) $(APPEND_LDFLAGS)
> +
> .PHONY: install
> install: all
> $(INSTALL_DIR) $(DESTDIR)$(LIBEXEC_BIN)
> diff --git a/tools/helpers/init-dom0less.c b/tools/helpers/init-dom0less.c
> new file mode 100644
> index 0000000000..0434ca064f
> --- /dev/null
> +++ b/tools/helpers/init-dom0less.c
> @@ -0,0 +1,266 @@
> +#include <stdbool.h>
> +#include <syslog.h>
> +#include <stdio.h>
> +#include <err.h>
> +#include <stdlib.h>
> +#include <xenstore.h>
> +#include <xenctrl.h>
> +#include <xenguest.h>
> +#include <libxl.h>
> +#include <xenevtchn.h>
> +
> +#include "init-dom-json.h"
> +
> +#define NR_MAGIC_PAGES 4
> +#define CONSOLE_PFN_OFFSET 0
> +#define XENSTORE_PFN_OFFSET 1
> +#define STR_MAX_LENGTH 64
> +
> +static int alloc_magic_pages(libxl_dominfo *info, struct xc_dom_image *dom)
> +{
> + int rc, i;
> + const xen_pfn_t base = GUEST_MAGIC_BASE >> XC_PAGE_SHIFT;
> + xen_pfn_t p2m[NR_MAGIC_PAGES];
> +
> + rc = xc_domain_setmaxmem(dom->xch, dom->guest_domid,
> + info->max_memkb + NR_MAGIC_PAGES * 4);
> + if (rc < 0)
> + return rc;
> +
> + for (i = 0; i < NR_MAGIC_PAGES; i++)
> + p2m[i] = base + i;
> +
> + rc = xc_domain_populate_physmap_exact(dom->xch, dom->guest_domid,
> + NR_MAGIC_PAGES, 0, 0, p2m);
> + if (rc < 0)
> + return rc;
> +
> + dom->xenstore_pfn = base + XENSTORE_PFN_OFFSET;
> +
> + xc_clear_domain_page(dom->xch, dom->guest_domid, dom->xenstore_pfn);
> +
> + xc_hvm_param_set(dom->xch, dom->guest_domid, HVM_PARAM_STORE_PFN,
> + dom->xenstore_pfn);
> + return 0;
> +}
> +
> +static void do_xs_write(struct xs_handle *xsh, xs_transaction_t t,
> + char *path, char *val)
> +{
> + if (!xs_write(xsh, t, path, val, strlen(val)))
> + fprintf(stderr, "writing %s to xenstore failed.\n", path);
Error here is ignored, do we really want that ?
> +}
> +
> +static void do_xs_write_dom(struct xs_handle *xsh, xs_transaction_t t,
> + domid_t domid, char *path, char *val)
> +{
> + char full_path[STR_MAX_LENGTH];
> +
> + snprintf(full_path, STR_MAX_LENGTH,
> + "/local/domain/%d/%s", domid, path);
> + do_xs_write(xsh, t, full_path, val);
> +}
> +
> +static void do_xs_write_libxl(struct xs_handle *xsh, xs_transaction_t t,
> + domid_t domid, char *path, char *val)
> +{
> + char full_path[STR_MAX_LENGTH];
> +
> + snprintf(full_path, STR_MAX_LENGTH,
> + "/libxl/%d/%s", domid, path);
> + do_xs_write(xsh, t, full_path, val);
> +}
> +
> +static void do_xs_write_vm(struct xs_handle *xsh, xs_transaction_t t,
> + libxl_uuid uuid, char *path, char *val)
> +{
> + char full_path[STR_MAX_LENGTH];
> +
> + snprintf(full_path, STR_MAX_LENGTH,
> + "/vm/" LIBXL_UUID_FMT "/%s", LIBXL_UUID_BYTES(uuid), path);
> + do_xs_write(xsh, t, full_path, val);
> +}
> +
> +static int restore_xenstore(struct xs_handle *xsh,
> + libxl_dominfo *info, libxl_uuid uuid,
> + evtchn_port_t xenstore_port)
> +{
> + domid_t domid;
> + int i;
> + char uuid_str[STR_MAX_LENGTH];
> + char dom_name_str[STR_MAX_LENGTH];
> + char vm_val_str[STR_MAX_LENGTH];
> + char id_str[STR_MAX_LENGTH];
> + char max_memkb_str[STR_MAX_LENGTH];
> + char cpu_str[STR_MAX_LENGTH];
> + char xenstore_port_str[STR_MAX_LENGTH];
> + char ring_ref_str[STR_MAX_LENGTH];
> + xs_transaction_t t;
> +
> + domid = info->domid;
> + snprintf(id_str, STR_MAX_LENGTH, "%d", domid);
> + snprintf(dom_name_str, STR_MAX_LENGTH, "dom0less-%d", domid);
> + snprintf(uuid_str, STR_MAX_LENGTH, LIBXL_UUID_FMT,
> LIBXL_UUID_BYTES(uuid));
> + snprintf(vm_val_str, STR_MAX_LENGTH,
> + "vm/" LIBXL_UUID_FMT, LIBXL_UUID_BYTES(uuid));
> + snprintf(max_memkb_str, STR_MAX_LENGTH, "%lu", info->max_memkb);
> + snprintf(ring_ref_str, STR_MAX_LENGTH, "%lld",
> + (GUEST_MAGIC_BASE >> XC_PAGE_SHIFT) + XENSTORE_PFN_OFFSET);
> + snprintf(xenstore_port_str, STR_MAX_LENGTH, "%d", xenstore_port);
> +
> +retry_transaction:
> + t = xs_transaction_start(xsh);
> + if (t == XBT_NULL)
> + return errno;
> +
All the following is very static and for a dummy reviewer (like me) kind of
magic.
Could you add a comment on top of this explaining how this list of entries was
created so that someone updating/reviewing this code can make sure it is right ?
> + /* /vm */
> + do_xs_write_vm(xsh, t, uuid, "name", dom_name_str);
> + do_xs_write_vm(xsh, t, uuid, "uuid", uuid_str);
> + do_xs_write_vm(xsh, t, uuid, "start_time", "0");
> +
> + /* /domain */
> + do_xs_write_dom(xsh, t, domid, "vm", vm_val_str);
> + do_xs_write_dom(xsh, t, domid, "name", dom_name_str);
> + do_xs_write_dom(xsh, t, domid, "cpu", "");
> + for (i = 0; i < info->vcpu_max_id; i++) {
> + snprintf(cpu_str, STR_MAX_LENGTH, "cpu/%d/availability/", i);
> + do_xs_write_dom(xsh, t, domid, cpu_str,
> + (info->cpupool & (1 << i)) ? "online" : "offline");
> + }
> + do_xs_write_dom(xsh, t, domid, "cpu/0", "");
> + do_xs_write_dom(xsh, t, domid, "cpu/availability", "online");
> +
> + do_xs_write_dom(xsh, t, domid, "memory", "");
> + do_xs_write_dom(xsh, t, domid, "memory/static-max", max_memkb_str);
> + do_xs_write_dom(xsh, t, domid, "memory/videoram", "-1");
> +
> + do_xs_write_dom(xsh, t, domid, "device", "");
> + do_xs_write_dom(xsh, t, domid, "device/suspend", "");
> + do_xs_write_dom(xsh, t, domid, "device/suspend/event-channel", "");
> +
> + do_xs_write_dom(xsh, t, domid, "control", "");
> + do_xs_write_dom(xsh, t, domid, "control/shutdown", "");
> + do_xs_write_dom(xsh, t, domid, "control/feature-poweroff", "1");
> + do_xs_write_dom(xsh, t, domid, "control/feature-reboot", "1");
> + do_xs_write_dom(xsh, t, domid, "control/feature-suspend", "");
> + do_xs_write_dom(xsh, t, domid, "control/sysrq", "");
> + do_xs_write_dom(xsh, t, domid,
> "control/platform-feature-multiprocessor-suspend", "1");
> + do_xs_write_dom(xsh, t, domid, "control",
> "platform-feature-xs_reset_watches");
> +
> + do_xs_write_dom(xsh, t, domid, "domid", id_str);
> + do_xs_write_dom(xsh, t, domid, "data", "");
> + do_xs_write_dom(xsh, t, domid, "drivers", "");
> + do_xs_write_dom(xsh, t, domid, "feature", "");
> + do_xs_write_dom(xsh, t, domid, "attr", "");
> +
> + do_xs_write_dom(xsh, t, domid, "store/port", xenstore_port_str);
> + do_xs_write_dom(xsh, t, domid, "store/ring-ref", ring_ref_str);
> +
> + do_xs_write_libxl(xsh, t, domid, "type", "pvh");
> + do_xs_write_libxl(xsh, t, domid, "dm-version", "qemu_xen");
> +
> + if (!xs_transaction_end(xsh, t, false))
> + if (errno == EAGAIN)
> + goto retry_transaction;
> +
> + return 0;
> +}
> +
> +static int init_domain(struct xs_handle *xsh, libxl_dominfo *info)
> +{
> + struct xc_dom_image dom;
> + libxl_uuid uuid;
> + uint64_t v;
> + int rc;
> +
> + printf("#### Init dom0less domain: %d ####\n", info->domid);
> + dom.guest_domid = info->domid;
> + dom.xenstore_domid = 0;
> + dom.xch = xc_interface_open(0, 0, 0);
> +
> + rc = xc_hvm_param_get(dom.xch, info->domid, HVM_PARAM_STORE_EVTCHN, &v);
> + if (rc != 0) {
> + printf("Failed to get HVM_PARAM_STORE_EVTCHN\n");
> + return 1;
> + }
> + dom.xenstore_evtchn = v;
> +
> + /* Console won't be initialized but set its data for completeness */
> + dom.console_domid = 0;
> +
> + /* Alloc magic pages */
> + printf("Allocating magic pages\n");
> + if (alloc_magic_pages(info, &dom) != 0) {
> + printf("Error on alloc magic pages\n");
> + return 1;
> + }
> +
> + printf("Setup Grant Tables\n");
> + xc_dom_gnttab_init(&dom);
> +
> + printf("Setup UUID\n");
> + libxl_uuid_generate(&uuid);
> + xc_domain_sethandle(dom.xch, info->domid, libxl_uuid_bytearray(&uuid));
> +
> + printf("Creating JSON\n");
> + rc = gen_stub_json_config(info->domid, &uuid);
> + if (rc)
> + err(1, "gen_stub_json_config");
> +
> + printf("Restoring Xenstore values\n");
> + restore_xenstore(xsh, info, uuid, dom.xenstore_evtchn);
> +
> + printf("Introducing domain\n");
> + xs_introduce_domain(xsh, info->domid,
> + (GUEST_MAGIC_BASE >> XC_PAGE_SHIFT) + XENSTORE_PFN_OFFSET,
> + dom.xenstore_evtchn);
This is really verbose and you have no option to make this a bit more quiet.
Do we really need all those prints ? Could end up being a lot if you have 5 or
6 domains.
> + return 0;
> +}
> +
> +/* Check if domain has been configured in XS */
> +static bool domain_exists(struct xs_handle *xsh, int domid)
> +{
> + return xs_is_domain_introduced(xsh, domid);
> +}
> +
> +int main(int argc, char **argv)
> +{
> + libxl_dominfo *info;
> + libxl_ctx *ctx;
> + int nb_vm, i;
> + struct xs_handle *xsh;
> +
> + xsh = xs_daemon_open();
> + if (xsh == NULL) {
> + fprintf(stderr, "Could not contact XenStore");
> + exit(1);
> + }
> +
> + if (libxl_ctx_alloc(&ctx, LIBXL_VERSION, 0, NULL)) {
> + fprintf(stderr, "cannot init xl context\n");
You might want to close xsh to be clean here
> + exit(1);
> + }
> +
> + info = libxl_list_domain(ctx, &nb_vm);
> + if (!info) {
> + fprintf(stderr, "libxl_list_vm failed.\n");
You might want to close xsh to be clean here
> + exit(EXIT_FAILURE);
Why using EXIT_FAILURE here but 1 on the exit before ?
> + }
> +
> + for (i = 0; i < nb_vm; i++) {
> + domid_t domid = info[i].domid;
> +
> + /* Don't need to check for Dom0 */
> + if (!domid)
> + continue;
> +
> + printf("Checking domid: %u\n", domid);
> + if (!domain_exists(xsh, domid))
> + init_domain(xsh, &info[i]);
> + else
> + printf("Domain %d has already been initialized\n", domid);
> + }
> + libxl_dominfo_list_free(info, nb_vm);
> + xs_close(xsh);
> + return 0;
> +}
> --
> 2.25.1
>
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