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

isaku.yamahata
2022-10-30T06:29:01Z

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) {
+ gfn_t s = max(start, slot->base_gfn);
+ gfn_t e = min(end, slot->base_gfn + slot->npages);
+
+ WARN_ON_ONCE(s >= e);
+ kvm_arch_update_mem_attr(kvm, slot, attr, s, e);
+ }
+ }
+
+ return r;
+}
+EXPORT_SYMBOL_GPL(kvm_vm_set_mem_attr);
+
#else /* !CONFIG_HAVE_KVM_RESTRICTED_MEM */

static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot)
--
2.25.1