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authorJoao Martins <joao.m.martins@oracle.com>2017-11-08 17:19:57 +0000
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2017-11-08 16:33:14 -0500
commit2229f70b5bbb025e1394b61007938a68060afbfb (patch)
tree9020b4a527c21dd34cd5f38672a790b88811f585 /arch/x86/xen
parentb888808093113ae7d63d213272d01fea4b8329ed (diff)
downloadlinux-2229f70b5bbb025e1394b61007938a68060afbfb.tar.bz2
x86/xen/time: setup vcpu 0 time info page
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> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Diffstat (limited to 'arch/x86/xen')
-rw-r--r--arch/x86/xen/suspend.c4
-rw-r--r--arch/x86/xen/time.c90
-rw-r--r--arch/x86/xen/xen-ops.h2
3 files changed, 95 insertions, 1 deletions
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index d6b1680693a9..800ed36ecfba 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -16,6 +16,8 @@
void xen_arch_pre_suspend(void)
{
+ xen_save_time_memory_area();
+
if (xen_pv_domain())
xen_pv_pre_suspend();
}
@@ -26,6 +28,8 @@ void xen_arch_post_suspend(int cancelled)
xen_pv_post_suspend(cancelled);
else
xen_hvm_post_suspend(cancelled);
+
+ xen_restore_time_memory_area();
}
static void xen_vcpu_notify_restore(void *data)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index c96e61fd70e7..c2041043c606 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -370,6 +370,92 @@ static const struct pv_time_ops xen_time_ops __initconst = {
.steal_clock = xen_steal_clock,
};
+static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
+
+void xen_save_time_memory_area(void)
+{
+ struct vcpu_register_time_memory_area t;
+ int ret;
+
+ if (!xen_clock)
+ return;
+
+ t.addr.v = NULL;
+
+ ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
+ if (ret != 0)
+ pr_notice("Cannot save secondary vcpu_time_info (err %d)",
+ ret);
+ else
+ clear_page(xen_clock);
+}
+
+void xen_restore_time_memory_area(void)
+{
+ struct vcpu_register_time_memory_area t;
+ int ret;
+
+ if (!xen_clock)
+ return;
+
+ t.addr.v = &xen_clock->pvti;
+
+ ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
+
+ /*
+ * We don't disable VCLOCK_PVCLOCK entirely if it fails to register the
+ * secondary time info with Xen or if we migrated to a host without the
+ * necessary flags. On both of these cases what happens is either
+ * process seeing a zeroed out pvti or seeing no PVCLOCK_TSC_STABLE_BIT
+ * bit set. Userspace checks the latter and if 0, it discards the data
+ * in pvti and fallbacks to a system call for a reliable timestamp.
+ */
+ if (ret != 0)
+ pr_notice("Cannot restore secondary vcpu_time_info (err %d)",
+ ret);
+}
+
+static void xen_setup_vsyscall_time_info(void)
+{
+ struct vcpu_register_time_memory_area t;
+ struct pvclock_vsyscall_time_info *ti;
+ int ret;
+
+ 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
+ * 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;
+}
+
static void __init xen_time_init(void)
{
struct pvclock_vcpu_time_info *pvti;
@@ -401,8 +487,10 @@ static void __init xen_time_init(void)
* bit is supported hence speeding up Xen clocksource.
*/
pvti = &__this_cpu_read(xen_vcpu)->time;
- if (pvti->flags & PVCLOCK_TSC_STABLE_BIT)
+ if (pvti->flags & PVCLOCK_TSC_STABLE_BIT) {
pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
+ xen_setup_vsyscall_time_info();
+ }
xen_setup_runstate_info(cpu);
xen_setup_timer(cpu);
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index c8a6d224f7ed..f96dbedb33d4 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -69,6 +69,8 @@ void xen_setup_runstate_info(int cpu);
void xen_teardown_timer(int cpu);
u64 xen_clocksource_read(void);
void xen_setup_cpu_clockevents(void);
+void xen_save_time_memory_area(void);
+void xen_restore_time_memory_area(void);
void __init xen_init_time_ops(void);
void __init xen_hvm_init_time_ops(void);