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Thu, 10 Oct 2024 11:26:06 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 10 Oct 2024 11:23:38 -0700 In-Reply-To: <20241010182427.1434605-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241010182427.1434605-1-seanjc@google.com> X-Mailer: git-send-email 2.47.0.rc1.288.g06298d1525-goog Message-ID: <20241010182427.1434605-37-seanjc@google.com> Subject: [PATCH v13 36/85] KVM: x86: Don't fault-in APIC access page during initial allocation From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Sean Christopherson Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, " =?utf-8?q?Alex_Benn=C3=A9e?= " , Yan Zhao , David Matlack , David Stevens , Andrew Jones Drop the gfn_to_page() lookup when installing KVM's internal memslot for the APIC access page, as KVM doesn't need to immediately fault-in the page now that the page isn't pinned. In the extremely unlikely event the kernel can't allocate a 4KiB page, KVM can just as easily return -EFAULT on the future page fault. Suggested-by: Paolo Bonzini Signed-off-by: Sean Christopherson --- arch/x86/kvm/lapic.c | 12 ------------ 1 file changed, 12 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 20526e4d6c62..65412640cfc7 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2647,7 +2647,6 @@ void kvm_apic_update_apicv(struct kvm_vcpu *vcpu) int kvm_alloc_apic_access_page(struct kvm *kvm) { - struct page *page; void __user *hva; int ret = 0; @@ -2663,17 +2662,6 @@ int kvm_alloc_apic_access_page(struct kvm *kvm) goto out; } - page = gfn_to_page(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); - if (!page) { - ret = -EFAULT; - goto out; - } - - /* - * Do not pin the page in memory, so that memory hot-unplug - * is able to migrate it. - */ - put_page(page); kvm->arch.apic_access_memslot_enabled = true; out: mutex_unlock(&kvm->slots_lock);