diff mbox series

[11/41] clocksource/hyperv: use MSR-based access if running as root

Message ID 20211104125449.16540-12-tim.gardner@canonical.com
State New
Headers show
Series Enable arm64 | expand

Commit Message

Tim Gardner Nov. 4, 2021, 12:54 p.m. UTC 
From: Wei Liu <wei.liu@kernel.org>

BugLink: https://bugs.launchpad.net/bugs/1949770

When Linux runs as the root partition, the setup required for TSC page
is different. Luckily Linux also has access to the MSR based
clocksource. We can just disable the TSC page clocksource if Linux is
the root partition.

Signed-off-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210203150435.27941-5-wei.liu@kernel.org
(cherry picked from commit 7d4163c8315729140ad99d6e1ab10dfc7a685640)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
---
 drivers/clocksource/hyperv_timer.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 4c9e6a87c438..10eb5c645141 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -455,6 +455,9 @@  static bool __init hv_init_tsc_clocksource(void)
 	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
 		return false;
 
+	if (hv_root_partition)
+		return false;
+
 	hv_read_reference_counter = read_hv_clock_tsc;
 	phys_addr = virt_to_phys(hv_get_tsc_page());