[PATCH v2 08/20] kvm: x86/mmu: Separate making non-leaf sptes from link_shadow_page

From: Ben Gardon
Date: Wed Oct 14 2020 - 14:27:41 EST


The TDP MMU page fault handler will need to be able to create non-leaf
SPTEs to build up the paging structures. Rather than re-implementing the
function, factor the SPTE creation out of link_shadow_page.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 337ab6823e312..05024b8ae5a4d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2468,21 +2468,30 @@ static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
__shadow_walk_next(iterator, *iterator->sptep);
}

-static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
- struct kvm_mmu_page *sp)
+static u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled)
{
u64 spte;

- BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK);
-
- spte = __pa(sp->spt) | shadow_present_mask | PT_WRITABLE_MASK |
+ spte = __pa(child_pt) | shadow_present_mask | PT_WRITABLE_MASK |
shadow_user_mask | shadow_x_mask | shadow_me_mask;

- if (sp_ad_disabled(sp))
+ if (ad_disabled)
spte |= SPTE_AD_DISABLED_MASK;
else
spte |= shadow_accessed_mask;

+ return spte;
+}
+
+static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
+ struct kvm_mmu_page *sp)
+{
+ u64 spte;
+
+ BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK);
+
+ spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp));
+
mmu_spte_set(sptep, spte);

mmu_page_add_parent_pte(vcpu, sp, sptep);
--
2.28.0.1011.ga647a8990f-goog