On 8/9/24 21:03, Sean Christopherson wrote:
Explicitly query the list of to-be-zapped shadow pages when checking to
see if unprotecting a gfn for retry has succeeded, i.e. if KVM should
retry the faulting instruction.
Add a comment to explain why the list needs to be checked before zapping,
which is the primary motivation for this change.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 300a47801685..50695eb2ee22 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2731,12 +2731,15 @@ bool __kvm_mmu_unprotect_gfn_and_retry(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
goto out;
}
- r = false;
write_lock(&kvm->mmu_lock);
- for_each_gfn_valid_sp_with_gptes(kvm, sp, gpa_to_gfn(gpa)) {
- r = true;
+ for_each_gfn_valid_sp_with_gptes(kvm, sp, gpa_to_gfn(gpa))
kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
- }
+
+ /*
+ * Snapshot the result before zapping, as zapping will remove all list
+ * entries, i.e. checking the list later would yield a false negative.
+ */
Hmm, the comment is kinda overkill? Maybe just
/* Return whether there were sptes to zap. */
r = !list_empty(&invalid_test);
I'm not sure about patch 21 - I like the simple kvm_mmu_unprotect_page()
function. Maybe rename it to kvm_mmu_zap_gfn() and make it static in
the same patch?
Either way, this small cleanup applies even if the function is not inlined.
Thanks,
Paolo
+ r = !list_empty(&invalid_list);
kvm_mmu_commit_zap_page(kvm, &invalid_list);
write_unlock(&kvm->mmu_lock);
