Messages in this thread | | | From | Paolo Bonzini <> | Subject | Re: [PATCH 10/14] KVM: x86: Further clarify the logic and comments for toggling log dirty | Date | Thu, 18 Feb 2021 17:56:05 +0100 |
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On 18/02/21 17:15, Sean Christopherson wrote: > On Thu, Feb 18, 2021, Paolo Bonzini wrote: >> On 13/02/21 01:50, Sean Christopherson wrote: >>> >>> - * Nothing to do for RO slots or CREATE/MOVE/DELETE of a slot. >>> - * See comments below. >>> + * Nothing to do for RO slots (which can't be dirtied and can't be made >>> + * writable) or CREATE/MOVE/DELETE of a slot. See comments below. >>> */ >>> if ((change != KVM_MR_FLAGS_ONLY) || (new->flags & KVM_MEM_READONLY)) >>> return; >>> + /* >>> + * READONLY and non-flags changes were filtered out above, and the only >>> + * other flag is LOG_DIRTY_PAGES, i.e. something is wrong if dirty >>> + * logging isn't being toggled on or off. >>> + */ >>> + if (WARN_ON_ONCE(!((old->flags ^ new->flags) & KVM_MEM_LOG_DIRTY_PAGES))) >>> + return; >>> + >> >> What about readonly -> readwrite changes? > > Not allowed without first deleting the memslot. See commit 75d61fbcf563 ("KVM: > set_memory_region: Disallow changing read-only attribute later"). RW->RO is > also not supported. > > if (!old.npages) { > change = KVM_MR_CREATE; > new.dirty_bitmap = NULL; > memset(&new.arch, 0, sizeof(new.arch)); > } else { /* Modify an existing slot. */ > if ((new.userspace_addr != old.userspace_addr) || > (new.npages != old.npages) || > ((new.flags ^ old.flags) & KVM_MEM_READONLY)) > return -EINVAL; >
Right you are, thanks. Then the warning would catch this quick. I queued 10 and 11 too, and will reply on 12 now that I looked at it more closely.
Paolo
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