linux-kernel - Re: [PATCH 06/22] kvm: mmu: Make address space ID a property of memslots

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Date:   Wed, 30 Sep 2020 16:11:59 -0700
From:   Ben Gardon <bgardon@...gle.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Cannon Matthews <cannonmatthews@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.com>, Peter Shier <pshier@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>
Subject: Re: [PATCH 06/22] kvm: mmu: Make address space ID a property of memslots

On Tue, Sep 29, 2020 at 11:11 PM Sean Christopherson
<sean.j.christopherson@...el.com> wrote:
>
> On Fri, Sep 25, 2020 at 02:22:46PM -0700, Ben Gardon wrote:
> > Save address space ID as a field in each memslot so that functions that
> > do not use rmaps (which implicitly encode the id) can handle multiple
> > address spaces correctly.
> >
> > Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
> > machine. This series introduced no new failures.
> >
> > This series can be viewed in Gerrit at:
> >       https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538
> >
> > Signed-off-by: Ben Gardon <bgardon@...gle.com>
> > ---
> >  include/linux/kvm_host.h | 1 +
> >  virt/kvm/kvm_main.c      | 1 +
> >  2 files changed, 2 insertions(+)
> >
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index 05e3c2fb3ef78..a460bc712a81c 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -345,6 +345,7 @@ struct kvm_memory_slot {
> >       struct kvm_arch_memory_slot arch;
> >       unsigned long userspace_addr;
> >       u32 flags;
> > +     int as_id;
>
> Ha!  Peter Xu's dirtly ring also added this.  This should be a u16, it'll
> save 8 bytes per memslot (oooooooh).  Any chance you want to include Peter's
> patch[*]?  It has some nitpicking from Peter and I regarding what to do
> with as_id on deletion.  That would also avoid silent merge conflicts on
> Peter's end.
>
> [*] https://lkml.kernel.org/r/20200708193408.242909-2-peterx@redhat.com

Oh that's great! Yes, let's use Peter's patch in place of this one.


>
> >       short id;
> >  };
> >
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index cf88233b819a0..f9c80351c9efd 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1318,6 +1318,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> >       new.npages = mem->memory_size >> PAGE_SHIFT;
> >       new.flags = mem->flags;
> >       new.userspace_addr = mem->userspace_addr;
> > +     new.as_id = as_id;
> >
> >       if (new.npages > KVM_MEM_MAX_NR_PAGES)
> >               return -EINVAL;
> > --
> > 2.28.0.709.gb0816b6eb0-goog
> >