* [PATCH v2] kexec-xen: Allow xen_kexec_exec() to return in case of Live Update
@ 2022-03-23 14:44 ` Raphael Ning
0 siblings, 0 replies; 4+ messages in thread
From: Raphael Ning @ 2022-03-23 14:44 UTC (permalink / raw)
To: Simon Horman; +Cc: kexec, Raphael Ning, Julien Grall, xen-devel, Raphael Ning
From: Raphael Ning <raphning@amazon.com>
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@amazon.com>
---
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2] kexec-xen: Allow xen_kexec_exec() to return in case of Live Update
@ 2022-03-23 14:44 ` Raphael Ning
0 siblings, 0 replies; 4+ messages in thread
From: Raphael Ning @ 2022-03-23 14:44 UTC (permalink / raw)
To: kexec
From: Raphael Ning <raphning@amazon.com>
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@amazon.com>
---
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] kexec-xen: Allow xen_kexec_exec() to return in case of Live Update
2022-03-23 14:44 ` Raphael Ning
@ 2022-03-23 14:59 ` Simon Horman
-1 siblings, 0 replies; 4+ messages in thread
From: Simon Horman @ 2022-03-23 14:59 UTC (permalink / raw)
To: Raphael Ning; +Cc: kexec, Julien Grall, xen-devel, Raphael Ning
On Wed, Mar 23, 2022 at 02:44:18PM +0000, Raphael Ning wrote:
> From: Raphael Ning <raphning@amazon.com>
>
> 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@amazon.com>
Thanks, applied.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2] kexec-xen: Allow xen_kexec_exec() to return in case of Live Update
@ 2022-03-23 14:59 ` Simon Horman
0 siblings, 0 replies; 4+ messages in thread
From: Simon Horman @ 2022-03-23 14:59 UTC (permalink / raw)
To: kexec
On Wed, Mar 23, 2022 at 02:44:18PM +0000, Raphael Ning wrote:
> From: Raphael Ning <raphning@amazon.com>
>
> 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@amazon.com>
Thanks, applied.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-03-23 14:59 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-03-23 14:44 [PATCH v2] kexec-xen: Allow xen_kexec_exec() to return in case of Live Update Raphael Ning
2022-03-23 14:44 ` Raphael Ning
2022-03-23 14:59 ` Simon Horman
2022-03-23 14:59 ` Simon Horman
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