• Sean Christopherson's avatar
    KVM: x86/mmu: Move shadow-present check out of spte_has_volatile_bits() · 54eb3ef5
    Sean Christopherson authored
    Move the is_shadow_present_pte() check out of spte_has_volatile_bits()
    and into its callers.  Well, caller, since only one of its two callers
    doesn't already do the shadow-present check.
    
    Opportunistically move the helper to spte.c/h so that it can be used by
    the TDP MMU, which is also the primary motivation for the shadow-present
    change.  Unlike the legacy MMU, the TDP MMU uses a single path for clear
    leaf and non-leaf SPTEs, and to avoid unnecessary atomic updates, the TDP
    MMU will need to check is_last_spte() prior to calling
    spte_has_volatile_bits(), and calling is_last_spte() without first
    calling is_shadow_present_spte() is at best odd, and at worst a violation
    of KVM's loosely defines SPTE rules.
    
    Note, mmu_spte_clear_track_bits() could likely skip the write entirely
    for SPTEs that are not shadow-present.  Leave that cleanup for a future
    patch to avoid introducing a functional change, and because the
    shadow-present check can likely be moved further up the stack, e.g.
    drop_large_spte() appears to be the only path that doesn't already
    explicitly check for a shadow-present SPTE.
    
    No functional change intended.
    
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
    Message-Id: <20220423034752.1161007-3-seanjc@google.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    54eb3ef5
spte.c 13.5 KB