From: Raphael Ning <raphning@xxxxxxxxxx> Currently, my_exec() does not expect the Xen KEXEC_CMD_kexec hypercall to return on success, because it assumes that the hypercall always triggers an immediate reboot. However, for Live Update, the hypercall merely schedules the kexec operation and returns; the actual reboot happens asynchronously. [1] Therefore, rework the Xen code path of my_exec() such that it does not treat a successfully processed Live Update request as an error. Also, rephrase the comment above the function to remove ambiguity. [1] https://lists.xen.org/archives/html/xen-devel/2021-05/msg00286.html Signed-off-by: Raphael Ning <raphning@xxxxxxxxxx> --- Changes in v2: - Fix --without-xen build. --- kexec/kexec-xen.c | 12 ++++++++---- kexec/kexec.c | 23 +++++++++++++++++++---- kexec/kexec.h | 2 +- 3 files changed, 28 insertions(+), 9 deletions(-) diff --git a/kexec/kexec-xen.c b/kexec/kexec-xen.c index 47da3da466f0..a7c89339c4b7 100644 --- a/kexec/kexec-xen.c +++ b/kexec/kexec-xen.c @@ -247,21 +247,24 @@ int xen_kexec_status(uint64_t kexec_flags) return ret; } -void xen_kexec_exec(uint64_t kexec_flags) +int xen_kexec_exec(uint64_t kexec_flags) { xc_interface *xch; uint8_t type = KEXEC_TYPE_DEFAULT; + int ret; xch = xc_interface_open(NULL, NULL, 0); if (!xch) - return; + return -1; if (kexec_flags & KEXEC_LIVE_UPDATE) type = KEXEC_TYPE_LIVE_UPDATE; - xc_kexec_exec(xch, type); + ret = xc_kexec_exec(xch, type); xc_interface_close(xch); + + return ret; } #else /* ! HAVE_LIBXENCTRL */ @@ -286,8 +289,9 @@ int xen_kexec_status(uint64_t kexec_flags) return -1; } -void xen_kexec_exec(uint64_t kexec_flags) +int xen_kexec_exec(uint64_t kexec_flags) { + return -1; } #endif diff --git a/kexec/kexec.c b/kexec/kexec.c index 7e4787bc8211..e7861049bbea 100644 --- a/kexec/kexec.c +++ b/kexec/kexec.c @@ -902,13 +902,28 @@ static int my_shutdown(void) } /* - * Exec the new kernel (reboot) + * Exec the new kernel. If successful, this triggers an immediate reboot + * and does not return, but Xen Live Update is an exception (more on this + * below). */ static int my_exec(void) { - if (xen_present()) - xen_kexec_exec(kexec_flags); - else + if (xen_present()) { + int ret; + + /* + * There are two cases in which the Xen hypercall may return: + * 1) An error occurred, e.g. the kexec image was not loaded. + * The exact error is indicated by errno. + * 2) Live Update was successfully scheduled. Note that unlike + * a normal kexec, Live Update happens asynchronously, i.e. + * the hypercall merely schedules the kexec operation and + * returns immediately. + */ + ret = xen_kexec_exec(kexec_flags); + if ((kexec_flags & KEXEC_LIVE_UPDATE) && !ret) + return 0; + } else reboot(LINUX_REBOOT_CMD_KEXEC); /* I have failed if I make it here */ fprintf(stderr, "kexec failed: %s\n", diff --git a/kexec/kexec.h b/kexec/kexec.h index 595dd681db6d..0f97a974cb8a 100644 --- a/kexec/kexec.h +++ b/kexec/kexec.h @@ -324,7 +324,7 @@ void cmdline_add_liveupdate(char **base); int xen_present(void); int xen_kexec_load(struct kexec_info *info); int xen_kexec_unload(uint64_t kexec_flags); -void xen_kexec_exec(uint64_t kexec_flags); +int xen_kexec_exec(uint64_t kexec_flags); int xen_kexec_status(uint64_t kexec_flags); extern unsigned long long get_kernel_sym(const char *text); -- 2.32.0 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
