clocksource/drivers/hyperv: Allocate Hyper-V TSC page statically

Prepare to add Hyper-V sched clock callback and move Hyper-V Reference TSC
initialization much earlier in the boot process.  Earlier initialization is
needed so that it happens while the timestamp value is still 0 and no
discontinuity in the timestamp will occur when pv_ops.time.sched_clock
calculates its offset.
    
The earlier initialization requires that the Hyper-V TSC page be allocated
statically instead of with vmalloc(), so fixup the references to the TSC
page and the method of getting its physical address.
    
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lkml.kernel.org/r/20190814123216.32245-2-Tianyu.Lan@microsoft.com

2 files changed, 5 insertions, 9 deletions

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 349a61d8bf34..f5937742b290 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -122,7 +122,7 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 
                 if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
                         return vmf_insert_pfn(vma, vmf->address,
-                                        vmalloc_to_pfn(tsc_pg));
+                                        virt_to_phys(tsc_pg) >> PAGE_SHIFT);
         }
 
         return VM_FAULT_SIGBUS;
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index ba2c79e6a0ee..432aa331df04 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -214,17 +214,17 @@ EXPORT_SYMBOL_GPL(hyperv_cs);
 
 #ifdef CONFIG_HYPERV_TSCPAGE
 
-static struct ms_hyperv_tsc_page *tsc_pg;
+static struct ms_hyperv_tsc_page tsc_pg __aligned(PAGE_SIZE);
 
 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
 {
-        return tsc_pg;
+        return &tsc_pg;
 }
 EXPORT_SYMBOL_GPL(hv_get_tsc_page);
 
 static u64 notrace read_hv_sched_clock_tsc(void)
 {
-        u64 current_tick = hv_read_tsc_page(tsc_pg);
+        u64 current_tick = hv_read_tsc_page(&tsc_pg);
 
         if (current_tick == U64_MAX)
                 hv_get_time_ref_count(current_tick);
@@ -280,12 +280,8 @@ static bool __init hv_init_tsc_clocksource(void)
         if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
                 return false;
 
-        tsc_pg = vmalloc(PAGE_SIZE);
-        if (!tsc_pg)
-                return false;
-
         hyperv_cs = &hyperv_cs_tsc;
-        phys_addr = page_to_phys(vmalloc_to_page(tsc_pg));
+        phys_addr = virt_to_phys(&tsc_pg);
 
         /*
          * The Hyper-V TLFS specifies to preserve the value of reserved