diff mbox series

[PULL,kvm-unit-tests,03/10] arm64: timer: Add ISB after register writes

Message ID 20200206162434.14624-4-drjones@redhat.com (mailing list archive)
State New, archived
Headers show
Series [PULL,kvm-unit-tests,01/10] Makefile: Use no-stack-protector compiler options | expand

Commit Message

Andrew Jones Feb. 6, 2020, 4:24 p.m. UTC 
From: Alexandru Elisei <alexandru.elisei@arm.com>

From ARM DDI 0487E.a glossary, the section "Context synchronization
event":

"All direct and indirect writes to System registers that are made before
the Context synchronization event affect any instruction, including a
direct read, that appears in program order after the instruction causing
the Context synchronization event."

The ISB instruction is a context synchronization event [1]. Add an ISB
after all register writes, to make sure that the writes have been
completed when we try to test their effects.

[1] ARM DDI 0487E.a, section C6.2.96

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 arm/timer.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/arm/timer.c b/arm/timer.c
index f390e8e65d31..c6ea108cfa4b 100644
--- a/arm/timer.c
+++ b/arm/timer.c
@@ -41,6 +41,7 @@  static u64 read_vtimer_cval(void)
 static void write_vtimer_cval(u64 val)
 {
 	write_sysreg(val, cntv_cval_el0);
+	isb();
 }
 
 static s32 read_vtimer_tval(void)
@@ -51,6 +52,7 @@  static s32 read_vtimer_tval(void)
 static void write_vtimer_tval(s32 val)
 {
 	write_sysreg(val, cntv_tval_el0);
+	isb();
 }
 
 static u64 read_vtimer_ctl(void)
@@ -61,6 +63,7 @@  static u64 read_vtimer_ctl(void)
 static void write_vtimer_ctl(u64 val)
 {
 	write_sysreg(val, cntv_ctl_el0);
+	isb();
 }
 
 static u64 read_ptimer_counter(void)
@@ -76,6 +79,7 @@  static u64 read_ptimer_cval(void)
 static void write_ptimer_cval(u64 val)
 {
 	write_sysreg(val, cntp_cval_el0);
+	isb();
 }
 
 static s32 read_ptimer_tval(void)
@@ -86,6 +90,7 @@  static s32 read_ptimer_tval(void)
 static void write_ptimer_tval(s32 val)
 {
 	write_sysreg(val, cntp_tval_el0);
+	isb();
 }
 
 static u64 read_ptimer_ctl(void)
@@ -96,6 +101,7 @@  static u64 read_ptimer_ctl(void)
 static void write_ptimer_ctl(u64 val)
 {
 	write_sysreg(val, cntp_ctl_el0);
+	isb();
 }
 
 struct timer_info {
@@ -181,7 +187,6 @@  static bool test_cval_10msec(struct timer_info *info)
 	before_timer = info->read_counter();
 	info->write_cval(before_timer + time_10ms);
 	info->write_ctl(ARCH_TIMER_CTL_ENABLE);
-	isb();
 
 	/* Wait for the timer to fire */
 	while (!(info->read_ctl() & ARCH_TIMER_CTL_ISTATUS))
@@ -217,11 +222,9 @@  static void test_timer(struct timer_info *info)
 	/* Enable the timer, but schedule it for much later */
 	info->write_cval(later);
 	info->write_ctl(ARCH_TIMER_CTL_ENABLE);
-	isb();
 	report(!gic_timer_pending(info), "not pending before");
 
 	info->write_cval(now - 1);
-	isb();
 	report(gic_timer_pending(info), "interrupt signal pending");
 
 	/* Disable the timer again and prepare to take interrupts */