clocksource/drivers/hyperv: add data structure for reference TSC MSR

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

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index bb47610bbd1c4ddee413a626cf8a6eed333b451a..18de1f439ffd5013ed7e1c09f7f4a70bdc8ad5a6 100644 (file)
--- 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 fdce7a4cfc6ffca0115bb08053dd2961c0fea50b..b17c6eeb9afa2e3ada6021ee6453913814383b51 100644 (file)
--- 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