lkml.org 
[lkml]   [2021]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH v6 25/29] KVM: Call kvm_arch_flush_shadow_memslot() on the old slot in kvm_invalidate_memslot()
    On Tue, Nov 30, 2021, Maciej S. Szmigiero wrote:
    > From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
    >
    > kvm_invalidate_memslot() calls kvm_arch_flush_shadow_memslot() on the
    > active, but KVM_MEMSLOT_INVALID slot.
    > Do it on the inactive (but valid) old slot instead since arch code really
    > should not get passed such invalid slot.

    One other thing that's worth noting in the changelog is that "old->arch" may have
    stale data. IMO that's perfectly ok, but it's definitely a quirk. Ideally KVM
    would disallow touching "arch" for an INVALID slot, but that would require another
    arch hook if kvm_prepare_memory_region() failed to refresh old->arch if necessary
    before restoring it. :-/

    Paolo, thoughts on this goofy case? I don't love it, but I dislike having

    kvm_arch_flush_shadow_memslot(kvm, invalid_slot);

    in the final code even more.

    Reviewed-by: Sean Christopherson <seanjc@google.com>

    > Suggested-by: Sean Christopherson <seanjc@google.com>
    > Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
    > ---
    > virt/kvm/kvm_main.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    >
    > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    > index c57748ee41e8..086f18969bc3 100644
    > --- a/virt/kvm/kvm_main.c
    > +++ b/virt/kvm/kvm_main.c
    > @@ -1632,7 +1632,7 @@ static void kvm_invalidate_memslot(struct kvm *kvm,
    > * - gfn_to_hva (kvm_read_guest, gfn_to_pfn)
    > * - kvm_is_visible_gfn (mmu_check_root)
    > */
    > - kvm_arch_flush_shadow_memslot(kvm, working_slot);
    > + kvm_arch_flush_shadow_memslot(kvm, old);
    >
    > /* Was released by kvm_swap_active_memslots, reacquire. */
    > mutex_lock(&kvm->slots_arch_lock);

    \
     
     \ /
      Last update: 2021-12-01 04:29    [W:2.119 / U:1.316 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site