[PATCH AUTOSEL 5.15 09/27] clocksource/drivers/hyperv: add data structure for reference TSC MSR

From: Sasha Levin
Date: Fri Nov 18 2022 - 21:23:14 EST


From: Anirudh Rayabharam <anrayabh@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit 4ad1aa571214e8d6468a1806794d987b374b5a08 ]

Add a data structure to represent the reference TSC MSR similar to
other MSRs. This simplifies the code for updating the MSR.

Signed-off-by: Anirudh Rayabharam <anrayabh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221027095729.1676394-2-anrayabh@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/clocksource/hyperv_timer.c | 29 +++++++++++++++--------------
include/asm-generic/hyperv-tlfs.h | 9 +++++++++
2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index bb47610bbd1c..18de1f439ffd 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -21,6 +21,7 @@
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/acpi.h>
+#include <linux/hyperv.h>
#include <clocksource/hyperv_timer.h>
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
@@ -395,25 +396,25 @@ static u64 notrace read_hv_sched_clock_tsc(void)

static void suspend_hv_clock_tsc(struct clocksource *arg)
{
- u64 tsc_msr;
+ union hv_reference_tsc_msr tsc_msr;

/* Disable the TSC page */
- tsc_msr = hv_get_register(HV_REGISTER_REFERENCE_TSC);
- tsc_msr &= ~BIT_ULL(0);
- hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr);
+ tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+ tsc_msr.enable = 0;
+ hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
}


static void resume_hv_clock_tsc(struct clocksource *arg)
{
phys_addr_t phys_addr = virt_to_phys(&tsc_pg);
- u64 tsc_msr;
+ union hv_reference_tsc_msr tsc_msr;

/* Re-enable the TSC page */
- tsc_msr = hv_get_register(HV_REGISTER_REFERENCE_TSC);
- tsc_msr &= GENMASK_ULL(11, 0);
- tsc_msr |= BIT_ULL(0) | (u64)phys_addr;
- hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr);
+ tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+ tsc_msr.enable = 1;
+ tsc_msr.pfn = HVPFN_DOWN(phys_addr);
+ hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);
}

#ifdef HAVE_VDSO_CLOCKMODE_HVCLOCK
@@ -495,7 +496,7 @@ static __always_inline void hv_setup_sched_clock(void *sched_clock) {}

static bool __init hv_init_tsc_clocksource(void)
{
- u64 tsc_msr;
+ union hv_reference_tsc_msr tsc_msr;
phys_addr_t phys_addr;

if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
@@ -530,10 +531,10 @@ static bool __init hv_init_tsc_clocksource(void)
* (which already has at least the low 12 bits set to zero since
* it is page aligned). Also set the "enable" bit, which is bit 0.
*/
- tsc_msr = hv_get_register(HV_REGISTER_REFERENCE_TSC);
- tsc_msr &= GENMASK_ULL(11, 0);
- tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
- hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr);
+ tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);
+ tsc_msr.enable = 1;
+ tsc_msr.pfn = HVPFN_DOWN(phys_addr);
+ hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);

clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);

diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 56348a541c50..1f314389e2be 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -102,6 +102,15 @@ struct ms_hyperv_tsc_page {
volatile s64 tsc_offset;
} __packed;

+union hv_reference_tsc_msr {
+ u64 as_uint64;
+ struct {
+ u64 enable:1;
+ u64 reserved:11;
+ u64 pfn:52;
+ } __packed;
+};
+
/*
* The guest OS needs to register the guest ID with the hypervisor.
* The guest ID is a 64 bit entity and the structure of this ID is
--
2.35.1