From: Catalin Marinas <catalin.marinas@xxxxxxx>
Commit 0b46b8a718c6 got back-ported to stable, but the later fix in commit
d6ad36913083d683 didn't as it wasn't appropriately Cc'd. This has left arm64
broken in stable when booted at EL2:
BUG: failure at ./arch/arm64/include/asm/arch_timer.h:112/arch_counter_get_cntpct()!
Mark.
---->8----
Commit d6ad36913083d683aad4e02e53580c995f1a6ede upstream.
Commit 0b46b8a718c6 (clocksource: arch_timer: Fix code to use physical
timers when requested) introduces the use of physical counters in the
ARM architected timer driver. However, he arm64 kernel uses CNTVCT in
VDSO. When booting in EL2, the kernel switches to the physical timers to
make things easier for KVM but it continues to use the virtual counter
both in user and kernel. While in such scenario CNTVCT == CNTPCT (since
CNTVOFF is initialised by the kernel to 0), we want to spot firmware
bugs corrupting CNTVOFF early (which would affect CNTVCT).
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Tested-by: Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Fixes: 0b46b8a718c6 ("clocksource: arch_timer: Fix code to use physical timers when requested")
Cc: Ian Campbell <ijc@xxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 3.18.x
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
---
drivers/clocksource/arm_arch_timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 1fa2af9..84b4c8b 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -462,7 +462,7 @@ static void __init arch_counter_register(unsigned type)
/* Register the CP15 based counter if we have one */
if (type & ARCH_CP15_TIMER) {
- if (arch_timer_use_virtual)
+ if (IS_ENABLED(CONFIG_ARM64) || arch_timer_use_virtual)
arch_timer_read_counter = arch_counter_get_cntvct;
else
arch_timer_read_counter = arch_counter_get_cntpct;
--
1.9.1
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