[Xen-devel] [RFC PATCH v3 09/12] x86/xen: save and restore steal clock

From: Anchal Agarwal <anchalag@amazon.com>
To: <tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>,
	<hpa@zytor.com>,  <x86@kernel.org>, <boris.ostrovsky@oracle.com>,
	<jgross@suse.com>, <linux-pm@vger.kernel.org>,
	<linux-mm@kvack.org>, <kamatam@amazon.com>,
	<sstabellini@kernel.org>, <konrad.wilk@oracle.com>,
	<roger.pau@citrix.com>, <axboe@kernel.dk>, <davem@davemloft.net>,
	<rjw@rjwysocki.net>, <len.brown@intel.com>, <pavel@ucw.cz>,
	<peterz@infradead.org>, <eduval@amazon.com>, <sblbir@amazon.com>,
	<anchalag@amazon.com>, <xen-devel@lists.xenproject.org>,
	<vkuznets@redhat.com>, <netdev@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <dwmw@amazon.co.uk>,
	<fllinden@amaozn.com>, <benh@kernel.crashing.org>
Subject: [Xen-devel] [RFC PATCH v3 09/12] x86/xen: save and restore steal clock
Date: Wed, 12 Feb 2020 22:34:13 +0000	[thread overview]
Message-ID: <20200212223413.GA4354@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com> (raw)

From: Munehisa Kamata <kamatam@amazon.com>

Save steal clock values of all present CPUs in the system core ops
suspend callbacks. Also, restore a boot CPU's steal clock in the system
core resume callback. For non-boot CPUs, restore after they're brought
up, because runstate info for non-boot CPUs are not active until then.

Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
Signed-off-by: Anchal Agarwal <anchalag@amazon.com>

---
Changes since V2:
    * Separate patch to add save/restore call to suspend/resume code
---
 arch/x86/xen/suspend.c | 13 ++++++++++++-
 arch/x86/xen/time.c    |  3 +++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index 784c4484100b..dae0f74f5390 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -91,12 +91,20 @@ void xen_arch_suspend(void)
 static int xen_syscore_suspend(void)
 {
 	struct xen_remove_from_physmap xrfp;
-	int ret;
+	int cpu, ret;
 
 	/* Xen suspend does similar stuffs in its own logic */
 	if (xen_suspend_mode_is_xen_suspend())
 		return 0;
 
+	for_each_present_cpu(cpu) {
+		/*
+		 * Nonboot CPUs are already offline, but the last copy of
+		 * runstate info is still accessible.
+		 */
+		xen_save_steal_clock(cpu);
+	}
+
 	xrfp.domid = DOMID_SELF;
 	xrfp.gpfn = __pa(HYPERVISOR_shared_info) >> PAGE_SHIFT;
 
@@ -118,6 +126,9 @@ static void xen_syscore_resume(void)
 
 	pvclock_resume();
 
+	/* Nonboot CPUs will be resumed when they're brought up */
+	xen_restore_steal_clock(smp_processor_id());
+
 	gnttab_resume();
 }
 
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index befbdd8b17f0..8cf632dda605 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -537,6 +537,9 @@ static void xen_hvm_setup_cpu_clockevents(void)
 {
 	int cpu = smp_processor_id();
 	xen_setup_runstate_info(cpu);
+	if (cpu)
+		xen_restore_steal_clock(cpu);
+
 	/*
 	 * xen_setup_timer(cpu) - snprintf is bad in atomic context. Hence
 	 * doing it xen_hvm_cpu_notify (which gets called by smp_init during
-- 
2.24.1.AMZN


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