• Paul Mackerras's avatar
    KVM: PPC: Book3S PR: Make HPT accesses and updates SMP-safe · 9308ab8e
    Paul Mackerras authored
    This adds a per-VM mutex to provide mutual exclusion between vcpus
    for accesses to and updates of the guest hashed page table (HPT).
    This also makes the code use single-byte writes to the HPT entry
    when updating of the reference (R) and change (C) bits.  The reason
    for doing this, rather than writing back the whole HPTE, is that on
    non-PAPR virtual machines, the guest OS might be writing to the HPTE
    concurrently, and writing back the whole HPTE might conflict with
    that.  Also, real hardware does single-byte writes to update R and C.
    
    The new mutex is taken in kvmppc_mmu_book3s_64_xlate() when reading
    the HPT and updating R and/or C, and in the PAPR HPT update hcalls
    (H_ENTER, H_REMOVE, etc.).  Having the mutex means that we don't need
    to use a hypervisor lock bit in the HPT update hcalls, and we don't
    need to be careful about the order in which the bytes of the HPTE are
    updated by those hcalls.
    
    The other change here is to make emulated TLB invalidations (tlbie)
    effective across all vcpus.  To do this we call kvmppc_mmu_pte_vflush
    for all vcpus in kvmppc_ppc_book3s_64_tlbie().
    
    For 32-bit, this makes the setting of the accessed and dirty bits use
    single-byte writes, and makes tlbie invalidate shadow HPTEs for all
    vcpus.
    
    With this, PR KVM can successfully run SMP guests.
    Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
    Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
    9308ab8e
kvm_host.h 14.4 KB