Messages in this thread | | | Date | Thu, 16 Jun 2022 16:54:33 +0200 | Subject | Re: [PATCH 01/10] KVM: Do not zero initialize 'pfn' in hva_to_pfn() | From | Paolo Bonzini <> |
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On 4/29/22 03:04, Sean Christopherson wrote: > Drop the unnecessary initialization of the local 'pfn' variable in > hva_to_pfn(). First and foremost, '0' is not an invalid pfn, it's a > perfectly valid pfn on most architectures. I.e. if hva_to_pfn() were to > return an "uninitializd" pfn, it would actually be interpeted as a legal > pfn by most callers. > > Second, hva_to_pfn() can't return an uninitialized pfn as hva_to_pfn() > explicitly sets pfn to an error value (or returns an error value directly) > if a helper returns failure, and all helpers set the pfn on success. > > Note, the zeroing of 'pfn' was introduced by commit 2fc843117d64 ("KVM: > reorganize hva_to_pfn"), and was unnecessary and misguided paranoia even > then. > > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > virt/kvm/kvm_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 0848430f36c6..04ed4334473c 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2567,7 +2567,7 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, > bool write_fault, bool *writable) > { > struct vm_area_struct *vma; > - kvm_pfn_t pfn = 0; > + kvm_pfn_t pfn; > int npages, r; > > /* we can do it either atomically or asynchronously, not both */
I wonder if it was needed to avoid uninitialized variable warnings on "return pfn;"...
Paolo
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