On Thu, Jul 6, 2023 at 11:10 AM Isaku Yamahata [off-list ref] wrote:

On Tue, Jul 04, 2023 at 04:50:50PM +0900,
David Stevens [off-list ref] wrote:

quoted

diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index cf2c6426a6fc..46c681dc45e6 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c

@@ -138,7 +138,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
             const struct kvm_memory_slot *slot,
             unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn,
             u64 old_spte, bool prefetch, bool can_unsync,
-            bool host_writable, u64 *new_spte)
+            bool host_writable, bool is_refcounted, u64 *new_spte)
 {
      int level = sp->role.level;
      u64 spte = SPTE_MMU_PRESENT_MASK;

@@ -188,6 +188,8 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,

      if (level > PG_LEVEL_4K)
              spte |= PT_PAGE_SIZE_MASK;
+     else if (is_refcounted)
+             spte |= SPTE_MMU_PAGE_REFCOUNTED;

Is REFCOUNTED for 4K page only?  What guarantees that large page doesn't have
FOLL_GET? or can we set the bit for large page?

Oh, you're right, it should apply to >4K pages as well. This was based
on stale thinking from earlier versions of this series.

-David