linux-kernel - [PATCH char-misc 1/1] Drivers: hv: vmbus: Make synic

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Date:   Mon, 30 Jul 2018 19:34:44 -0700
From:   mhkelley58@...il.com
To:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
        vkuznets@...hat.com, jasowang@...hat.com,
        marcelo.cerri@...onical.com, sthemmin@...rosoft.com,
        kys@...rosoft.com
Cc:     mikelley@...rosoft.com
Subject: [PATCH char-misc 1/1] Drivers: hv: vmbus: Make synic_initialized flag per-cpu

From: Michael Kelley <mikelley@...rosoft.com>

The synic_initialized flag is part of the global hv_context
structure.  But the Hyper-V synthetic interrupt controller is
fundamentally a per-cpu device, and other synic related
fields are in hv_per_cpu_context.  In a multi-CPU system,
synic_initialized gets set multiple times, making the test in
hv_synic_cleanup() invalid.  Fix this by moving the flag to
hv_per_cpu_context and adjusting the references.

Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
---
 drivers/hv/hv.c           | 16 +++++++---------
 drivers/hv/hyperv_vmbus.h |  4 ++--
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 312fe5e..8d4fe0e 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -33,9 +33,7 @@
 #include "hyperv_vmbus.h"
 
 /* The one and only */
-struct hv_context hv_context = {
-	.synic_initialized	= false,
-};
+struct hv_context hv_context;
 
 /*
  * If false, we're using the old mechanism for stimer0 interrupts
@@ -315,7 +313,7 @@ int hv_synic_init(unsigned int cpu)
 
 	hv_set_synic_state(sctrl.as_uint64);
 
-	hv_context.synic_initialized = true;
+	hv_cpu->synic_initialized = true;
 
 	/*
 	 * Register the per-cpu clockevent source.
@@ -354,6 +352,8 @@ void hv_synic_clockevents_cleanup(void)
  */
 int hv_synic_cleanup(unsigned int cpu)
 {
+	struct hv_per_cpu_context *hv_cpu
+		= per_cpu_ptr(hv_context.cpu_context, cpu);
 	union hv_synic_sint shared_sint;
 	union hv_synic_simp simp;
 	union hv_synic_siefp siefp;
@@ -362,7 +362,7 @@ int hv_synic_cleanup(unsigned int cpu)
 	bool channel_found = false;
 	unsigned long flags;
 
-	if (!hv_context.synic_initialized)
+	if (!hv_cpu->synic_initialized)
 		return -EFAULT;
 
 	/*
@@ -395,12 +395,8 @@ int hv_synic_cleanup(unsigned int cpu)
 
 	/* Turn off clockevent device */
 	if (ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE) {
-		struct hv_per_cpu_context *hv_cpu
-			= this_cpu_ptr(hv_context.cpu_context);
-
 		clockevents_unbind_device(hv_cpu->clk_evt, cpu);
 		hv_ce_shutdown(hv_cpu->clk_evt);
-		put_cpu_ptr(hv_cpu);
 	}
 
 	hv_get_synint_state(VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
@@ -428,5 +424,7 @@ int hv_synic_cleanup(unsigned int cpu)
 	sctrl.enable = 0;
 	hv_set_synic_state(sctrl.as_uint64);
 
+	hv_cpu->synic_initialized = false;
+
 	return 0;
 }
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 72eaba3..eadd3df 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -202,6 +202,8 @@ enum {
 struct hv_per_cpu_context {
 	void *synic_message_page;
 	void *synic_event_page;
+	bool synic_initialized;
+
 	/*
 	 * buffer to post messages to the host.
 	 */
@@ -230,8 +232,6 @@ struct hv_context {
 
 	void *tsc_page;
 
-	bool synic_initialized;
-
 	struct hv_per_cpu_context __percpu *cpu_context;
 
 	/*
-- 
1.8.3.1