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([2001:b07:6468:f312:399d:3ef7:647c:b12d]) by smtp.gmail.com with ESMTPSA id p7sm28032996wrf.31.2020.04.16.06.52.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Apr 2020 06:52:08 -0700 (PDT) Subject: Re: [PATCH 0/2] KVM: x86/mmu: Minor cleanup in try_async_pf() To: Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Rick Edgecombe References: <20200415214414.10194-1-sean.j.christopherson@intel.com> From: Paolo Bonzini Message-ID: <29248fbf-f0fd-74e6-3edb-ee5ad1e0b33d@redhat.com> Date: Thu, 16 Apr 2020 15:52:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200415214414.10194-1-sean.j.christopherson@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/04/20 23:44, Sean Christopherson wrote: > > I'm not 100% on whether or not open coding the private memslot check in > patch 2 is a good idea. Avoiding the extra memslot lookup is nice, but > that could be done by providing e.g. kvm_is_memslot_visible(). Yeah, that's better. The patch is so small that it's even pointless to split it in two: From: Paolo Bonzini Subject: [PATCH] KVM: x86/mmu: Avoid an extra memslot lookup in try_async_pf() for L2 Create a new function kvm_is_visible_memslot() and use it from kvm_is_visible_gfn(); use the new function in try_async_pf() too, to avoid an extra memslot lookup. Suggested-by: Sean Christopherson Signed-off-by: Paolo Bonzini diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 6d6cb9416179..fe04ce843a57 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4082,19 +4082,18 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, gpa_t cr2_or_gpa, kvm_pfn_t *pfn, bool write, bool *writable) { - struct kvm_memory_slot *slot; + struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); bool async; /* * Don't expose private memslots to L2. */ - if (is_guest_mode(vcpu) && !kvm_is_visible_gfn(vcpu->kvm, gfn)) { + if (is_guest_mode(vcpu) && !kvm_is_visible_memslot(slot)) { *pfn = KVM_PFN_NOSLOT; *writable = false; return false; } - slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); async = false; *pfn = __gfn_to_pfn_memslot(slot, gfn, false, &async, write, writable); if (!async) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 658215f6102c..7d4f1eb70274 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1357,6 +1357,12 @@ static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val) } #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ +static inline bool kvm_is_visible_memslot(struct kvm_memory_slot *memslot) +{ + return (memslot && memslot->id < KVM_USER_MEM_SLOTS && + !(memslot->flags & KVM_MEMSLOT_INVALID)); +} + struct kvm_vcpu *kvm_get_running_vcpu(void); struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index da8fd45e0e3e..8aa577db131e 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1607,11 +1607,7 @@ bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn) { struct kvm_memory_slot *memslot = gfn_to_memslot(kvm, gfn); - if (!memslot || memslot->id >= KVM_USER_MEM_SLOTS || - memslot->flags & KVM_MEMSLOT_INVALID) - return false; - - return true; + return kvm_is_visible_memslot(memslot); } EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);