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

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Date:   Fri, 18 Nov 2022 21:13:34 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Sasha Levin <sashal@...nel.org>,
        kys@...rosoft.com, haiyangz@...rosoft.com, decui@...rosoft.com,
        daniel.lezcano@...aro.org, tglx@...utronix.de,
        linux-hyperv@...r.kernel.org, linux-arch@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 09/27] clocksource/drivers/hyperv: add data structure for reference TSC MSR

From: Anirudh Rayabharam <anrayabh@...ux.microsoft.com>

[ 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@...ux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
Link: https://lore.kernel.org/r/20221027095729.1676394-2-anrayabh@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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