| Message ID | 20240404185034.3184582-8-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: guest_memfd: New hooks and functionality for SEV-SNP and TDX | expand |
On Thu, Apr 04, 2024 at 02:50:29PM -0400, 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) > { > pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff; > - struct kvm_gmem *gmem; > + struct kvm_gmem *gmem = file->private_data; > struct folio *folio; > struct page *page; > - struct file *file; > int r; > > - file = kvm_gmem_get_file(slot); > - if (!file) > + if (file != slot->gmem.file) { > + WARN_ON_ONCE(slot->gmem.file); > return -EFAULT; > + } > > gmem = file->private_data; > - > if (xa_load(&gmem->bindings, index) != slot) { > WARN_ON_ONCE(xa_load(&gmem->bindings, index)); > - r = -EIO; > - goto out_fput; > + return -EIO; > } > > folio = kvm_gmem_get_folio(file_inode(file), index, true); This should be: folio = kvm_gmem_get_folio(file_inode(file), index, prepare); Otherwise: Reviewed-by: Michael Roth <michael.roth@amd.com> -Mike > - if (!folio) { > - r = -ENOMEM; > - goto out_fput; > - } > + if (!folio) > + return -ENOMEM; > > if (folio_test_hwpoison(folio)) { > r = -EHWPOISON; > @@ -583,9 +579,21 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, > > out_unlock: > folio_unlock(folio); > -out_fput: > - fput(file); > > return r; > } > + > +int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, > + gfn_t gfn, kvm_pfn_t *pfn, int *max_order) > +{ > + struct file *file = kvm_gmem_get_file(slot); > + int r; > + > + if (!file) > + return -EFAULT; > + > + r = __kvm_gmem_get_pfn(file, slot, gfn, pfn, max_order, true); > + fput(file); > + return r; > +} > EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn); > -- > 2.43.0 > >
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.
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.
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) { pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff; - struct kvm_gmem *gmem; + struct kvm_gmem *gmem = file->private_data; struct folio *folio; struct page *page; - struct file *file; int r; - file = kvm_gmem_get_file(slot); - if (!file) + if (file != slot->gmem.file) { + WARN_ON_ONCE(slot->gmem.file); return -EFAULT; + } gmem = file->private_data; - if (xa_load(&gmem->bindings, index) != slot) { WARN_ON_ONCE(xa_load(&gmem->bindings, index)); - r = -EIO; - goto out_fput; + return -EIO; } folio = kvm_gmem_get_folio(file_inode(file), index, true); - if (!folio) { - r = -ENOMEM; - goto out_fput; - } + if (!folio) + return -ENOMEM; if (folio_test_hwpoison(folio)) { r = -EHWPOISON; @@ -583,9 +579,21 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, out_unlock: folio_unlock(folio); -out_fput: - fput(file); return r; } + +int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, + gfn_t gfn, kvm_pfn_t *pfn, int *max_order) +{ + struct file *file = kvm_gmem_get_file(slot); + int r; + + if (!file) + return -EFAULT; + + r = __kvm_gmem_get_pfn(file, slot, gfn, pfn, max_order, true); + fput(file); + return r; +} EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn);
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(-)