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Subject[PATCH 2/4] drivers/clocksource/hyper-v: Introduce TSC MSR register structure
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From: Stanislav Kinsburskiy <stanislav.kinsburskiy@gmail.com>

And rework the code to use it instead of the physical address.
This is a cleanup and precursor patch for upcoming support for TSC page
mapping into hyper-v root partition.

Signed-off-by: Stanislav Kinsburskiy <stanislav.kinsburskiy@gmail.com>
CC: "K. Y. Srinivasan" <kys@microsoft.com>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: Wei Liu <wei.liu@kernel.org>
CC: Dexuan Cui <decui@microsoft.com>
CC: Daniel Lezcano <daniel.lezcano@linaro.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: linux-hyperv@vger.kernel.org
CC: linux-kernel@vger.kernel.org
---
drivers/clocksource/hyperv_timer.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index c4dbf40a3d3e..d447bc99a399 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -367,6 +367,12 @@ static union {
} tsc_pg __aligned(PAGE_SIZE);

static struct ms_hyperv_tsc_page *tsc_page = &tsc_pg.page;
+static unsigned long tsc_pfn;
+
+static unsigned long hv_get_tsc_pfn(void)
+{
+ return tsc_pfn;
+}

struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
{
@@ -408,13 +414,12 @@ static void suspend_hv_clock_tsc(struct clocksource *arg)

static void resume_hv_clock_tsc(struct clocksource *arg)
{
- phys_addr_t phys_addr = virt_to_phys(tsc_page);
union hv_reference_tsc_msr tsc_msr;

/* Re-enable the TSC page */
tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
tsc_msr.enable = 1;
- tsc_msr.pfn = __phys_to_pfn(phys_addr);
+ tsc_msr.pfn = tsc_pfn;
hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
}

@@ -498,7 +503,6 @@ static __always_inline void hv_setup_sched_clock(void *sched_clock) {}
static bool __init hv_init_tsc_clocksource(void)
{
union hv_reference_tsc_msr tsc_msr;
- phys_addr_t phys_addr;

if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
return false;
@@ -523,7 +527,7 @@ static bool __init hv_init_tsc_clocksource(void)
}

hv_read_reference_counter = read_hv_clock_tsc;
- phys_addr = virt_to_phys(hv_get_tsc_page());
+ tsc_pfn = __phys_to_pfn(virt_to_phys(tsc_page));

/*
* The Hyper-V TLFS specifies to preserve the value of reserved
@@ -534,7 +538,7 @@ static bool __init hv_init_tsc_clocksource(void)
*/
tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
tsc_msr.enable = 1;
- tsc_msr.pfn = __phys_to_pfn(phys_addr);
+ tsc_msr.pfn = tsc_pfn;
hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);

clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);

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