+
+static void xen_setup_vsyscall_time_info(void)
+{
+ struct vcpu_register_time_memory_area t;
+ struct pvclock_vsyscall_time_info *ti;
+ int ret;

In the previous version you'd return immediately if
PVCLOCK_TSC_STABLE_BIT was not set. Don't you still need to check this? Especially give...

+
+ ti = (struct pvclock_vsyscall_time_info *)get_zeroed_page(GFP_KERNEL); + if (!ti)
+ return;
+
+ t.addr.v = &ti->pvti;
+
+ ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t); + if (ret) {
+ pr_notice("xen: VCLOCK_PVCLOCK not supported (err %d)\n", ret); + free_page((unsigned long)ti);
+ return;
+ }
+
+ /*
+ * If primary time info had this bit set, secondary should too since

... this comment?

-boris

+ * it's the same data on both just different memory regions. But we
+ * still check it in case hypervisor is buggy.
+ */
+ if (!(ti->pvti.flags & PVCLOCK_TSC_STABLE_BIT)) {
+ t.addr.v = NULL;
+ ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, + 0, &t);
+ if (!ret)
+ free_page((unsigned long)ti);
+
+ pr_notice("xen: VCLOCK_PVCLOCK not supported (tsc unstable)\n");
+ return;
+ }
+
+ xen_clock = ti;
+ pvclock_set_pvti_cpu0_va(xen_clock);
+
+ xen_clocksource.archdata.vclock_mode = VCLOCK_PVCLOCK;
+}
+

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

In order to support pvclock vdso on xen we need to setup the time
info page for vcpu 0 and register the page with Xen using the VCPUOP_register_vcpu_time_memory_area hypercall. This hypercall
will also forcefully update the pvti which will set some of the
necessary flags for vdso. Afterwards we check if it supports the PVCLOCK_TSC_STABLE_BIT flag which is mandatory for having
vdso/vsyscall support. And if so, it will set the cpu 0 pvti that
will be later on used when mapping the vdso image.

The xen headers are also updated to include the new hypercall for
registering the secondary vcpu_time_info struct.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
---
Changes since v4:
* Remove pvclock_set_flags since predecessor patch will set in
xen_time_init. Consequently pvti local variable is not so useful
and doesn't make things more clear - therefore remove it.
* Adjust comment on xen_setup_vsyscall_time_info()
* Add Juergen's Reviewed-by (Retained as there wasn't functional
changes)

Changes since v3:
(Comments from Juergen)
* Remove _t added suffix from *GUEST_HANDLE* when sync vcpu.h
with the latest

Changes since v2:
(Comments from Juergen)
* Omit the blank after the cast on all 3 occurrences.
* Change last VCLOCK_PVCLOCK message to be more descriptive
* Sync the complete vcpu.h header instead of just adding the
needed one. (IOW adding VCPUOP_get_physid)

Changes since v1:
* Check flags ahead to see if the primary clock can use
PVCLOCK_TSC_STABLE_BIT even if secondary registration fails.
(Comments from Boris)
* Remove addr, addr variables;
* Change first pr_debug to pr_warn;
* Change last pr_debug to pr_notice;