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  • Vitaly Kuznetsov's avatar
    x86/hyper-v: Use hypercall for remote TLB flush · 2ffd9e33
    Vitaly Kuznetsov authored
    
    
    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: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
    Reviewed-by: default avatarStephen 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: default avatarIngo Molnar <mingo@kernel.org>
    2ffd9e33