Re: [PATCH v10 060/108] KVM: Add functions to set GFN to private or shared

Isaku Yamahata
2022-11-03T02:02:07Z

On Tue, Nov 01, 2022 at 06:21:26PM +0800,
Xiaoyao Li <xiaoyao.li@intel.com> wrote:

> On 10/30/2022 2:23 PM, isaku.yamahata@intel.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@intel.com>
> >
> > TDX KVM support needs to track whether GFN is private or shared. Introduce
> > functions to set whether GFN is private or shared and pre-allocate memory
> > for xarray.
> >
> > Suggested-by: Sean Christopherson <seanjc@google.com>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> > ---
> > include/linux/kvm_host.h | 11 ++++++
> > virt/kvm/kvm_main.c | 74 ++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 85 insertions(+)
> >
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index a0b64308d240..fac07886ab39 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -2307,9 +2307,20 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr)
> > #define KVM_MEM_ATTR_PRIVATE 0x0002
> > #ifdef __KVM_HAVE_ARCH_UPDATE_MEM_ATTR
> > +/* memory attr on [start, end) */
> > +int kvm_vm_reserve_mem_attr(struct kvm *kvm, gfn_t start, gfn_t end);
> > +int kvm_vm_set_mem_attr(struct kvm *kvm, int attr, gfn_t start, gfn_t end);
> > void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot,
> > unsigned int attr, gfn_t start, gfn_t end);
> > #else
> > +static inline int kvm_vm_reserve_mem_attr(struct kvm *kvm, gfn_t start, gfn_t end)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > +static inline int kvm_vm_set_mem_attr(struct kvm *kvm, int attr, gfn_t start, gfn_t end)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > static inline void kvm_arch_update_mem_attr(struct kvm *kvm,
> > struct kvm_memory_slot *slot,
> > unsigned int attr,
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 9f82b03a8118..f0e77b65939b 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1121,6 +1121,80 @@ static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot)
> > &slot->notifier);
> > }
> > +/*
> > + * Reserve memory for [start, end) so that the next set oepration won't fail
> > + * with -ENOMEM.
> > + */
> > +int kvm_vm_reserve_mem_attr(struct kvm *kvm, gfn_t start, gfn_t end)
> > +{
> > + int r = 0;
> > + gfn_t gfn;
> > +
> > + xa_lock(&kvm->mem_attr_array);
> > + for (gfn = start; gfn < end; gfn++) {
> > + r = __xa_insert(&kvm->mem_attr_array, gfn, NULL, GFP_KERNEL_ACCOUNT);
> > + if (r == -EBUSY)
> > + r = 0;
> > + if (r)
> > + break;
> > + }
> > + xa_unlock(&kvm->mem_attr_array);
> > +
> > + return r;
> > +}
> > +EXPORT_SYMBOL_GPL(kvm_vm_reserve_mem_attr);
> > +
> > +/* Set memory attr for [start, end) */
> > +int kvm_vm_set_mem_attr(struct kvm *kvm, int attr, gfn_t start, gfn_t end)
> > +{
> > + void *entry;
> > + gfn_t gfn;
> > + int r;
> > + int i;
> > +
> > + /* By default, the entry is private. */
> > + switch (attr) {
> > + case KVM_MEM_ATTR_PRIVATE:
> > + entry = NULL;
> > + break;
> > + case KVM_MEM_ATTR_SHARED:
> > + entry = xa_mk_value(KVM_MEM_ATTR_SHARED);
> > + break;
> > + default:
> > + WARN_ON_ONCE(1);
> > + return -EINVAL;
> > + }
> > +
> > + WARN_ON_ONCE(start >= end);
> > + for (gfn = start; gfn < end; gfn++) {
> > + r = xa_err(xa_store(&kvm->mem_attr_array, gfn, entry,
> > + GFP_KERNEL_ACCOUNT));
> > + if (r)
> > + break;
> > + }
> > + if (start >= gfn)
> > + return r;
> > +
> > + end = gfn;
> > + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
> > + struct kvm_memslot_iter iter;
> > + struct kvm_memory_slot *slot;
> > + struct kvm_memslots *slots;
> > +
> > + slots = __kvm_memslots(kvm, i);
> > + kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
>
> slot needs to be set as
>
> slot = iter.slot;
>

Thanks, will fix it.

--
Isaku Yamahata <isaku.yamahata@gmail.com>