From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
michael.roth@amd.com, isaku.yamahata@intel.com
Subject: Re: [PATCH 07/11] KVM: guest_memfd: extract __kvm_gmem_get_pfn()
Date: Wed, 24 Apr 2024 15:59:57 -0700 [thread overview]
Message-ID: <ZimO7V2udx8KB2Li@google.com> (raw)
In-Reply-To: <ZimI8j9LIUsAArdD@google.com>
On Wed, Apr 24, 2024, Sean Christopherson wrote:
> On Thu, Apr 04, 2024, Paolo Bonzini wrote:
> > In preparation for adding a function that walks a set of pages
> > provided by userspace and populates them in a guest_memfd,
> > add a version of kvm_gmem_get_pfn() that has a "bool prepare"
> > argument and passes it down to kvm_gmem_get_folio().
> >
> > Populating guest memory has to call repeatedly __kvm_gmem_get_pfn()
> > on the same file, so make the new function take struct file*.
> >
> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > ---
> > virt/kvm/guest_memfd.c | 38 +++++++++++++++++++++++---------------
> > 1 file changed, 23 insertions(+), 15 deletions(-)
> >
> > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> > index 486748e65f36..a537a7e63ab5 100644
> > --- a/virt/kvm/guest_memfd.c
> > +++ b/virt/kvm/guest_memfd.c
> > @@ -540,33 +540,29 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot)
> > fput(file);
> > }
> >
> > -int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
> > - gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
> > +static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
> > + gfn_t gfn, kvm_pfn_t *pfn, int *max_order, bool prepare)
>
> I genuinely don't know what it means to "prepare" a guest_memfd. I see it becomes
>
> if (!prepare)
> fgp_flags |= FGP_CREAT_ONLY;
>
> but I find the name "prepare" to be extremely unhelpful.
Ah, I'm blind. Maybe "do_prepare", or "do_arch_prepare"? To make it clear that
it's a command, not a description of the operation (which is how I first read it).
And I feel like overloading it to also mean FGP_CREAT_ONLY when _not_ preparing
the memory is odd.
if (prepare) {
int r = kvm_gmem_prepare_folio(inode, index, folio);
if (r < 0) {
folio_unlock(folio);
folio_put(folio);
return ERR_PTR(r);
}
}
Instead of "prepare" as a command, would it make sense to describe the "populating"
case? Because I think it's more intuitive that populating _needs_ to operate on
new, unprepared data.
next prev parent reply other threads:[~2024-04-24 22:59 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-04 18:50 [PATCH 00/11] KVM: guest_memfd: New hooks and functionality for SEV-SNP and TDX Paolo Bonzini
2024-04-04 18:50 ` [PATCH 01/11] mm: Introduce AS_INACCESSIBLE for encrypted/confidential memory Paolo Bonzini
2024-04-29 13:14 ` Vlastimil Babka
2024-04-04 18:50 ` [PATCH 02/11] KVM: guest_memfd: Use AS_INACCESSIBLE when creating guest_memfd inode Paolo Bonzini
2024-04-29 13:15 ` Vlastimil Babka
2024-04-04 18:50 ` [PATCH 03/11] KVM: guest_memfd: pass error up from filemap_grab_folio Paolo Bonzini
2024-04-04 18:50 ` [PATCH 04/11] filemap: add FGP_CREAT_ONLY Paolo Bonzini
2024-04-25 5:52 ` Paolo Bonzini
2024-04-29 13:26 ` Vlastimil Babka
2024-04-04 18:50 ` [PATCH 05/11] KVM: guest_memfd: limit overzealous WARN Paolo Bonzini
2024-04-04 18:50 ` [PATCH 06/11] KVM: guest_memfd: Add hook for initializing memory Paolo Bonzini
2024-04-22 10:53 ` Xu Yilun
2024-05-07 16:17 ` Paolo Bonzini
2024-04-04 18:50 ` [PATCH 07/11] KVM: guest_memfd: extract __kvm_gmem_get_pfn() Paolo Bonzini
2024-04-09 23:35 ` Michael Roth
2024-04-24 22:34 ` Sean Christopherson
2024-04-24 22:59 ` Sean Christopherson [this message]
2024-04-04 18:50 ` [PATCH 08/11] KVM: guest_memfd: extract __kvm_gmem_punch_hole() Paolo Bonzini
2024-04-04 18:50 ` [PATCH 09/11] KVM: guest_memfd: Add interface for populating gmem pages with user data Paolo Bonzini
2024-04-22 14:44 ` Xu Yilun
2024-04-23 23:50 ` Isaku Yamahata
2024-04-24 22:24 ` Sean Christopherson
2024-04-25 1:12 ` Isaku Yamahata
2024-04-25 6:01 ` Paolo Bonzini
2024-04-25 16:00 ` Sean Christopherson
2024-04-25 16:51 ` Isaku Yamahata
2024-04-26 5:44 ` Paolo Bonzini
2024-04-26 17:15 ` Isaku Yamahata
2024-04-26 5:41 ` Paolo Bonzini
2024-04-26 15:17 ` Sean Christopherson
2024-04-24 22:32 ` Sean Christopherson
2024-04-25 5:56 ` Paolo Bonzini
2024-04-04 18:50 ` [PATCH 10/11] KVM: guest_memfd: Add hook for invalidating memory Paolo Bonzini
2024-04-04 18:50 ` [PATCH 11/11] KVM: x86: Add gmem hook for determining max NPT mapping level Paolo Bonzini
2024-04-09 23:46 ` Michael Roth
2024-04-19 18:26 ` Isaku Yamahata
2024-04-22 14:52 ` Xu Yilun
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