Before switching to non-secure, make sure that CNTVOFF is set
to zero on all CPUs. Otherwise, kernel running in non-secure
without HYP enabled (hence using virtual timers) may observe
timers that are not synchronized, effectively seeing time
going backward...
Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
---
arch/arm/cpu/armv7/nonsec_virt.S | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/arm/cpu/armv7/nonsec_virt.S b/arch/arm/cpu/armv7/nonsec_virt.S
index 12de5c2..b5c946f 100644
--- a/arch/arm/cpu/armv7/nonsec_virt.S
+++ b/arch/arm/cpu/armv7/nonsec_virt.S
@@ -38,10 +38,10 @@ _secure_monitor:
bic r1, r1, #0x4e @ clear IRQ, FIQ, EA, nET bits
orr r1, r1, #0x31 @ enable NS, AW, FW bits
-#ifdef CONFIG_ARMV7_VIRT
mrc p15, 0, r0, c0, c1, 1 @ read ID_PFR1
and r0, r0, #CPUID_ARM_VIRT_MASK @ mask virtualization bits
cmp r0, #(1 << CPUID_ARM_VIRT_SHIFT)
+#ifdef CONFIG_ARMV7_VIRT
orreq r1, r1, #0x100 @ allow HVC instruction
#endif
@@ -52,7 +52,14 @@ _secure_monitor:
mrceq p15, 0, r0, c12, c0, 1 @ get MVBAR value
mcreq p15, 4, r0, c12, c0, 0 @ write HVBAR
#endif
+ bne 1f
+ @ Reset CNTVOFF to 0 before leaving monitor mode
+ mrc p15, 0, r0, c0, c1, 1 @ read ID_PFR1
+ ands r0, r0, #CPUID_ARM_GENTIMER_MASK @ test arch timer bits
+ movne r0, #0
+ mcrrne p15, 4, r0, r0, c14 @ Reset CNTVOFF to zero
+1:
movs pc, lr @ return to non-secure SVC
_hyp_trap:
--
1.9.2
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