diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2022-06-22 15:27:07 -0400 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-06-24 04:51:59 -0400 |
commit | 0cd8dc739833080aa0813cbd94d907a93e3a14c3 (patch) | |
tree | fb572c83818487c93a6f30d64e52fea4ff909bef /arch/x86/kvm/mmu/paging_tmpl.h | |
parent | 20d49186c0302015c229e23c7e63855cbacc8032 (diff) |
KVM: x86/mmu: pull call to drop_large_spte() into __link_shadow_page()
Before allocating a child shadow page table, all callers check
whether the parent already points to a huge page and, if so, they
drop that SPTE. This is done by drop_large_spte().
However, dropping the large SPTE is really only necessary before the
sp is installed. While the sp is returned by kvm_mmu_get_child_sp(),
installing it happens later in __link_shadow_page(). Move the call
there instead of having it in each and every caller.
To ensure that the shadow page is not linked twice if it was present,
do _not_ opportunistically make kvm_mmu_get_child_sp() idempotent:
instead, return an error value if the shadow page already existed.
This is a bit more verbose, but clearer than NULL.
Finally, now that the drop_large_spte() name is not taken anymore,
remove the two underscores in front of __drop_large_spte().
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu/paging_tmpl.h')
-rw-r--r-- | arch/x86/kvm/mmu/paging_tmpl.h | 31 |
1 files changed, 14 insertions, 17 deletions
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 24f292f3f93f..2448fa8d8438 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -648,15 +648,13 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, gfn_t table_gfn; clear_sp_write_flooding_count(it.sptep); - drop_large_spte(vcpu, it.sptep); - sp = NULL; - if (!is_shadow_present_pte(*it.sptep)) { - table_gfn = gw->table_gfn[it.level - 2]; - access = gw->pt_access[it.level - 2]; - sp = kvm_mmu_get_child_sp(vcpu, it.sptep, table_gfn, - false, access); + table_gfn = gw->table_gfn[it.level - 2]; + access = gw->pt_access[it.level - 2]; + sp = kvm_mmu_get_child_sp(vcpu, it.sptep, table_gfn, + false, access); + if (sp != ERR_PTR(-EEXIST)) { /* * We must synchronize the pagetable before linking it * because the guest doesn't need to flush tlb when @@ -685,7 +683,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, if (FNAME(gpte_changed)(vcpu, gw, it.level - 1)) goto out_gpte_changed; - if (sp) + if (sp != ERR_PTR(-EEXIST)) link_shadow_page(vcpu, it.sptep, sp); } @@ -709,16 +707,15 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, validate_direct_spte(vcpu, it.sptep, direct_access); - drop_large_spte(vcpu, it.sptep); + sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, + true, direct_access); + if (sp == ERR_PTR(-EEXIST)) + continue; - if (!is_shadow_present_pte(*it.sptep)) { - sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, - true, direct_access); - link_shadow_page(vcpu, it.sptep, sp); - if (fault->huge_page_disallowed && - fault->req_level >= it.level) - account_huge_nx_page(vcpu->kvm, sp); - } + link_shadow_page(vcpu, it.sptep, sp); + if (fault->huge_page_disallowed && + fault->req_level >= it.level) + account_huge_nx_page(vcpu->kvm, sp); } if (WARN_ON_ONCE(it.level != fault->goal_level)) |