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KVM: x86/mmu: Avoid reacquiring RCU if TDP MMU fails to allocate an SP

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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: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20240611220512.2426439-5-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
David Matlack 2024-06-11 15:05:12 -07:00 committed by Sean Christopherson
parent 3d4a5a45ca
commit 0089c055b5
1 changed files with 5 additions and 7 deletions
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12
arch/x86/kvm/mmu/tdp_mmu.c
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@ -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;
}