Commit 0089c055 authored by David Matlack's avatar David Matlack Committed by Sean Christopherson
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KVM: x86/mmu: Avoid reacquiring RCU if TDP MMU fails to allocate an SP 



Avoid needlessly reacquiring the RCU read lock if the TDP MMU fails to
allocate a shadow page during eager page splitting. Opportunistically
drop the local variable ret as well now that it's no longer necessary.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20240611220512.2426439-5-dmatlack@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 3d4a5a45

arch/x86/kvm/mmu/tdp_mmu.c

+5 −7
Original line number Diff line number Diff line
@@ -1402,7 +1402,6 @@ static int tdp_mmu_split_huge_pages_root(struct kvm *kvm, 
{

	struct kvm_mmu_page *sp = NULL;

	struct tdp_iter iter;

	int ret = 0;



	rcu_read_lock();
@@ -1440,16 +1439,15 @@ static int tdp_mmu_split_huge_pages_root(struct kvm *kvm, 
			else

				write_lock(&kvm->mmu_lock);



			rcu_read_lock();



			if (!sp) {

				ret = -ENOMEM;

				trace_kvm_mmu_split_huge_page(iter.gfn,

							      iter.old_spte,

							      iter.level, ret);

				break;

							      iter.level, -ENOMEM);

				return -ENOMEM;

			}



			rcu_read_lock();



			iter.yielded = true;

			continue;

		}
@@ -1472,7 +1470,7 @@ static int tdp_mmu_split_huge_pages_root(struct kvm *kvm, 
	if (sp)

		tdp_mmu_free_sp(sp);



	return ret;

	return 0;

}