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x86/hyper-v: Use hypercall for remote TLB flush
Hyper-V host can suggest us to use hypercall for doing remote TLB flush, this is supposed to work faster than IPIs. Implementation details: to do HvFlushVirtualAddress{Space,List} hypercalls we need to put the input somewhere in memory and we don't really want to have memory allocation on each call so we pre-allocate per cpu memory areas on boot. pv_ops patching is happening very early so we need to separate hyperv_setup_mmu_ops() and hyper_alloc_mmu(). It is possible and easy to implement local TLB flushing too and there is even a hint for that. However, I don't see a room for optimization on the host side as both hypercall and native tlb flush will result in vmexit. The hint is also not set on modern Hyper-V versions. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Reviewed-by: Stephen Hemminger <sthemmin@microsoft.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jork Loeser <Jork.Loeser@microsoft.com> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Simon Xiao <sixiao@microsoft.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: devel@linuxdriverproject.org Link: http://lkml.kernel.org/r/20170802160921.21791-8-vkuznets@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -1 +1 @@
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obj-y := hv_init.o
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obj-y := hv_init.o mmu.o
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@ -140,6 +140,8 @@ void hyperv_init(void)
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hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
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wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
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hyper_alloc_mmu();
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/*
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* Register Hyper-V specific clocksource.
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*/
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138
arch/x86/hyperv/mmu.c
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138
arch/x86/hyperv/mmu.c
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@ -0,0 +1,138 @@
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#define pr_fmt(fmt) "Hyper-V: " fmt
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#include <linux/hyperv.h>
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#include <linux/log2.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <asm/fpu/api.h>
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#include <asm/mshyperv.h>
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#include <asm/msr.h>
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#include <asm/tlbflush.h>
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/* HvFlushVirtualAddressSpace, HvFlushVirtualAddressList hypercalls */
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struct hv_flush_pcpu {
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u64 address_space;
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u64 flags;
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u64 processor_mask;
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u64 gva_list[];
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};
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/* Each gva in gva_list encodes up to 4096 pages to flush */
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#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE)
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static struct hv_flush_pcpu __percpu *pcpu_flush;
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/*
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* Fills in gva_list starting from offset. Returns the number of items added.
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*/
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static inline int fill_gva_list(u64 gva_list[], int offset,
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unsigned long start, unsigned long end)
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{
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int gva_n = offset;
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unsigned long cur = start, diff;
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do {
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diff = end > cur ? end - cur : 0;
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gva_list[gva_n] = cur & PAGE_MASK;
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/*
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* Lower 12 bits encode the number of additional
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* pages to flush (in addition to the 'cur' page).
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*/
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if (diff >= HV_TLB_FLUSH_UNIT)
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gva_list[gva_n] |= ~PAGE_MASK;
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else if (diff)
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gva_list[gva_n] |= (diff - 1) >> PAGE_SHIFT;
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cur += HV_TLB_FLUSH_UNIT;
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gva_n++;
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} while (cur < end);
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return gva_n - offset;
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}
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static void hyperv_flush_tlb_others(const struct cpumask *cpus,
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const struct flush_tlb_info *info)
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{
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int cpu, vcpu, gva_n, max_gvas;
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struct hv_flush_pcpu *flush;
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u64 status = U64_MAX;
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unsigned long flags;
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if (!pcpu_flush || !hv_hypercall_pg)
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goto do_native;
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if (cpumask_empty(cpus))
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return;
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local_irq_save(flags);
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flush = this_cpu_ptr(pcpu_flush);
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if (info->mm) {
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flush->address_space = virt_to_phys(info->mm->pgd);
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flush->flags = 0;
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} else {
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flush->address_space = 0;
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flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES;
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}
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flush->processor_mask = 0;
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if (cpumask_equal(cpus, cpu_present_mask)) {
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flush->flags |= HV_FLUSH_ALL_PROCESSORS;
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} else {
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for_each_cpu(cpu, cpus) {
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vcpu = hv_cpu_number_to_vp_number(cpu);
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if (vcpu >= 64)
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goto do_native;
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__set_bit(vcpu, (unsigned long *)
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&flush->processor_mask);
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}
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}
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/*
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* We can flush not more than max_gvas with one hypercall. Flush the
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* whole address space if we were asked to do more.
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*/
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max_gvas = (PAGE_SIZE - sizeof(*flush)) / sizeof(flush->gva_list[0]);
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if (info->end == TLB_FLUSH_ALL) {
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flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY;
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status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
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flush, NULL);
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} else if (info->end &&
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((info->end - info->start)/HV_TLB_FLUSH_UNIT) > max_gvas) {
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status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
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flush, NULL);
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} else {
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gva_n = fill_gva_list(flush->gva_list, 0,
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info->start, info->end);
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status = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST,
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gva_n, 0, flush, NULL);
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}
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local_irq_restore(flags);
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if (!(status & HV_HYPERCALL_RESULT_MASK))
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return;
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do_native:
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native_flush_tlb_others(cpus, info);
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}
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void hyperv_setup_mmu_ops(void)
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{
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if (ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED) {
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pr_info("Using hypercall for remote TLB flush\n");
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pv_mmu_ops.flush_tlb_others = hyperv_flush_tlb_others;
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setup_clear_cpu_cap(X86_FEATURE_PCID);
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}
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}
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void hyper_alloc_mmu(void)
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{
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if (ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED)
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pcpu_flush = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
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}
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@ -307,6 +307,8 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
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}
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void hyperv_init(void);
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void hyperv_setup_mmu_ops(void);
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void hyper_alloc_mmu(void);
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void hyperv_report_panic(struct pt_regs *regs);
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bool hv_is_hypercall_page_setup(void);
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void hyperv_cleanup(void);
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@ -314,6 +316,7 @@ void hyperv_cleanup(void);
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static inline void hyperv_init(void) {}
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static inline bool hv_is_hypercall_page_setup(void) { return false; }
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static inline void hyperv_cleanup(void) {}
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static inline void hyperv_setup_mmu_ops(void) {}
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#endif /* CONFIG_HYPERV */
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#ifdef CONFIG_HYPERV_TSCPAGE
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@ -242,6 +242,8 @@
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(~((1ull << HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT) - 1))
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/* Declare the various hypercall operations. */
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#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE 0x0002
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#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST 0x0003
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#define HVCALL_NOTIFY_LONG_SPIN_WAIT 0x0008
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#define HVCALL_POST_MESSAGE 0x005c
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#define HVCALL_SIGNAL_EVENT 0x005d
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@ -259,6 +261,11 @@
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#define HV_PROCESSOR_POWER_STATE_C2 2
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#define HV_PROCESSOR_POWER_STATE_C3 3
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#define HV_FLUSH_ALL_PROCESSORS BIT(0)
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#define HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES BIT(1)
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#define HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY BIT(2)
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#define HV_FLUSH_USE_EXTENDED_RANGE_FORMAT BIT(3)
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/* hypercall status code */
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#define HV_STATUS_SUCCESS 0
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#define HV_STATUS_INVALID_HYPERCALL_CODE 2
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@ -249,6 +249,7 @@ static void __init ms_hyperv_init_platform(void)
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* Setup the hook to get control post apic initialization.
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*/
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x86_platform.apic_post_init = hyperv_init;
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hyperv_setup_mmu_ops();
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#endif
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}
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@ -3,6 +3,7 @@ menu "Microsoft Hyper-V guest support"
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config HYPERV
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tristate "Microsoft Hyper-V client drivers"
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depends on X86 && ACPI && PCI && X86_LOCAL_APIC && HYPERVISOR_GUEST
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select PARAVIRT
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help
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Select this option to run Linux as a Hyper-V client operating
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system.
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