diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2022-11-17 19:05:51 +0300 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-11-17 19:10:25 +0300 |
commit | 63d28a25e04cb48e6bd15141506645ac99d9f8b2 (patch) | |
tree | 2a28b0d226d56e9c300c11f94d9d7e56f3ee1f6b /arch | |
parent | c4b33d28ea51c7d194b19a41c96a4f973cc0a280 (diff) | |
download | linux-63d28a25e04cb48e6bd15141506645ac99d9f8b2.tar.xz |
KVM: x86/mmu: simplify kvm_tdp_mmu_map flow when guest has to retry
A removed SPTE is never present, hence the "if" in kvm_tdp_mmu_map
only fails in the exact same conditions that the earlier loop
tested in order to issue a "break". So, instead of checking twice the
condition (upper level SPTEs could not be created or was frozen), just
exit the loop with a goto---the usual poor-man C replacement for RAII
early returns.
While at it, do not use the "ret" variable for return values of
functions that do not return a RET_PF_* enum. This is clearer
and also makes it possible to initialize ret to RET_PF_RETRY.
Suggested-by: Robert Hoo <robert.hu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 40 |
1 files changed, 19 insertions, 21 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index e08596775427..771210ce5181 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1159,7 +1159,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) struct kvm *kvm = vcpu->kvm; struct tdp_iter iter; struct kvm_mmu_page *sp; - int ret; + int ret = RET_PF_RETRY; kvm_mmu_hugepage_adjust(vcpu, fault); @@ -1168,23 +1168,25 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) rcu_read_lock(); tdp_mmu_for_each_pte(iter, mmu, fault->gfn, fault->gfn + 1) { + int r; + if (fault->nx_huge_page_workaround_enabled) disallowed_hugepage_adjust(fault, iter.old_spte, iter.level); if (iter.level == fault->goal_level) break; - /* Step down into the lower level page table if it exists. */ - if (is_shadow_present_pte(iter.old_spte) && - !is_large_pte(iter.old_spte)) - continue; - /* * If SPTE has been frozen by another thread, just give up and * retry, avoiding unnecessary page table allocation and free. */ if (is_removed_spte(iter.old_spte)) - break; + goto retry; + + /* Step down into the lower level page table if it exists. */ + if (is_shadow_present_pte(iter.old_spte) && + !is_large_pte(iter.old_spte)) + continue; /* * The SPTE is either non-present or points to a huge page that @@ -1196,13 +1198,17 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) sp->nx_huge_page_disallowed = fault->huge_page_disallowed; if (is_shadow_present_pte(iter.old_spte)) - ret = tdp_mmu_split_huge_page(kvm, &iter, sp, true); + r = tdp_mmu_split_huge_page(kvm, &iter, sp, true); else - ret = tdp_mmu_link_sp(kvm, &iter, sp, true); + r = tdp_mmu_link_sp(kvm, &iter, sp, true); - if (ret) { + /* + * Also force the guest to retry the access if the upper level SPTEs + * aren't in place. + */ + if (r) { tdp_mmu_free_sp(sp); - break; + goto retry; } if (fault->huge_page_disallowed && @@ -1213,18 +1219,10 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) } } - /* - * Force the guest to retry the access if the upper level SPTEs aren't - * in place, or if the target leaf SPTE is frozen by another CPU. - */ - if (iter.level != fault->goal_level || is_removed_spte(iter.old_spte)) { - rcu_read_unlock(); - return RET_PF_RETRY; - } - ret = tdp_mmu_map_handle_target_level(vcpu, fault, &iter); - rcu_read_unlock(); +retry: + rcu_read_unlock(); return ret; } |