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[35.247.111.240]) by smtp.gmail.com with ESMTPSA id k69sm7020641pgc.45.2021.05.05.09.00.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 May 2021 09:00:05 -0700 (PDT) Date: Wed, 5 May 2021 16:00:01 +0000 From: Sean Christopherson To: Kai Huang Cc: kvm@vger.kernel.org, pbonzini@redhat.com, bgardon@google.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org Subject: Re: [PATCH 1/3] KVM: x86/mmu: Fix return value in tdp_mmu_map_handle_target_level() Message-ID: References: <00875eb37d6b5cc9d19bb19e31db3130ac1d8730.1620200410.git.kai.huang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <00875eb37d6b5cc9d19bb19e31db3130ac1d8730.1620200410.git.kai.huang@intel.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, May 05, 2021, Kai Huang wrote: > Currently tdp_mmu_map_handle_target_level() returns 0, which is > RET_PF_RETRY, when page fault is actually fixed. This makes > kvm_tdp_mmu_map() also return RET_PF_RETRY in this case, instead of > RET_PF_FIXED. Fix by initializing ret to RET_PF_FIXED. Probably worth adding a blurb to call out that the bad return value is benign since kvm_mmu_page_fault() resumes the guest on RET_PF_RETRY or RET_PF_FIXED. And for good measure, a Fixes without stable@. Fixes: bb18842e2111 ("kvm: x86/mmu: Add TDP MMU PF handler") Reviewed-by: Sean Christopherson Side topic... Ben, does the TDP MMU intentionally not prefetch pages? If so, why not? > Signed-off-by: Kai Huang > --- > arch/x86/kvm/mmu/tdp_mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index ff0ae030004d..1cad4c9f7c34 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -905,7 +905,7 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, int write, > kvm_pfn_t pfn, bool prefault) > { > u64 new_spte; > - int ret = 0; > + int ret = RET_PF_FIXED; > int make_spte_ret = 0; > > if (unlikely(is_noslot_pfn(pfn))) > -- > 2.31.1 >