KVM: x86/mmu: Optimize MMU page cache lookup for fully direct MMUs

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Skip the unsync checks and the write flooding clearing for fully direct
MMUs, which are guaranteed to not have unsync'd or indirect pages (write
flooding detection only applies to indirect pages).  For TDP, this
avoids unnecessary memory reads and writes, and for the write flooding
count will also avoid dirtying a cache line (unsync_child_bitmap itself
consumes a cache line, i.e. write_flooding_count is guaranteed to be in
a different cache line than parent_ptes).

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200623194027.23135-3-sean.j.christopherson@intel.com>
Reviewed-By: Jon Cargille <jcargill@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Sean Christopherson 2020-06-23 12:40:27 -07:00 • committed by Paolo Bonzini

parent ac101b7cb1

commit fb58a9c345

1 changed files with 7 additions and 2 deletions

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arch/x86/kvm/mmu/mmu.c

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