Re: [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory

[Paolo Bonzini <pbonzini@redhat.com>]

On 4/22/22 12:56, Chao Peng wrote:
>          /* memfile notifier flags */
>          #define MFN_F_USER_INACCESSIBLE   0x0001  /* memory allocated in the file is inaccessible from userspace (e.g. read/write/mmap) */
>          #define MFN_F_UNMOVABLE           0x0002  /* memory allocated in the file is unmovable */
>          #define MFN_F_UNRECLAIMABLE       0x0003  /* memory allocated in the file is unreclaimable (e.g. via kswapd or any other pathes) */

You probably mean BIT(0/1/2) here.

Paolo

>      When memfile_notifier is being registered, memfile_register_notifier will
>      need check these flags. E.g. for MFN_F_USER_INACCESSIBLE, it fails when
>      previous mmap-ed mapping exists on the fd (I'm still unclear on how to do
>      this). When multiple consumers are supported it also need check all
>      registered consumers to see if any conflict (e.g. all consumers should have
>      MFN_F_USER_INACCESSIBLE set). Only when the register succeeds, the fd is
>      converted into a private fd, before that, the fd is just a normal (shared)
>      one. During this conversion, the previous data is preserved so you can put
>      some initial data in guest pages (whether the architecture allows this is
>      architecture-specific and out of the scope of this patch).