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    Subject[PATCH 1/2] clocksource/Hyper-v: Allocate Hyper-V tsc page statically
    Date
    From: Tianyu Lan <Tianyu.Lan@microsoft.com>

    This is to prepare to add Hyper-V sched clock callback and move
    Hyper-V reference TSC initialization much earlier in the boot
    process when timestamp is 0. So no discontinuity is observed
    when pv_ops.time.sched_clock to calculate its offset. This 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>
    ---
    arch/x86/entry/vdso/vma.c | 2 +-
    drivers/clocksource/hyperv_timer.c | 12 ++++--------
    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..86764ec9a854 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) & PAGE_MASK;

    /*
    * The Hyper-V TLFS specifies to preserve the value of reserved
    --
    2.14.5
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