[PATCH v6 04/16] clocksource/hyperv: use MSR-based access if running as root
From: Wei Liu <wei.liu@kernel.org>
Date: 2021-02-03 15:16:25
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Subsystem:
clocksource, clockevent drivers, hyper-v/azure core and drivers, the rest · Maintainers:
Daniel Lezcano, Thomas Gleixner, "K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Linus Torvalds
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 <redacted> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Michael Kelley <redacted> --- drivers/clocksource/hyperv_timer.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index ba04cb381cd3..269a691bd2c4 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c@@ -426,6 +426,9 @@ 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());
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2.20.1