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b=q5wzc5tBoiGBsuRhpRnOXn+/JuA2Y0L1EtRojaOy61UqRCGrwmOi61B2T1bcDZaV7 NbeRh9B8kksCJt8R7pFX3UfmmSq/2LH88b9pMLZWTv2gnx4GpA7DoH+Ua+/V5vG0Nk hQ9OiK295o+5817rlVHgqnSFpwuxD94ALmfSL/fo+n9Eqg2oPkF9PNzAWoq+5vRQyS L84JYDrUOnGdWUMq7ZD58Z1trqP5rnJGDBgLeKsRca2aKXrhpgBlqIPrNxvH9n1XP1 tdm7TK+oNWh6Sghw9RDsr0XR1COHVxmNS79Ysf/5OIwilPqZvdbbq19zgYHTJOcM6C Q1X6HLwip4qhg== Date: Fri, 12 Apr 2024 11:44:09 +0100 From: Will Deacon To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Thomas Bogendoerfer , Nicholas Piggin , Anup Patel , Atish Patra , Sean Christopherson , Andrew Morton , David Hildenbrand , 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-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH 1/4] KVM: delete .change_pte MMU notifier callback Message-ID: <20240412104408.GA27645@willie-the-truck> References: <20240405115815.3226315-1-pbonzini@redhat.com> <20240405115815.3226315-2-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240405115815.3226315-2-pbonzini@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Stat-Signature: qd4639kqtung7ckaoytto5bw3zuo4fi1 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: A4100C0006 X-Rspam-User: X-HE-Tag: 1712918658-487072 X-HE-Meta: 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 yinhZghX /LWr/tdEGtmFK6Mj5uENiu8O8957PX3CeSwRefij8GLR/2JzrJ10VTApCzEskt6n1su8SHPyHalblB78pjrZM+skS8t0ud21QWEgSgfeACjTAB8Ww4vu9ZKD8lf+V04X5vwZJlh/iJHZ1x59EpmIxGhmu9k+xibn8KNJRdDZIPHWa2L+mqjIvBHvmAPZwnfr+juzrqm5JoJkoqnOwNFoRWaoayFCaKSCrpwm3X2oSWi4l/9rblyXti+vZTssawPCjVMb2zX6ZPJmnCv2+PJMtTRHAGq8/WLxBBSTYZwJzolKC0PQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 05, 2024 at 07:58:12AM -0400, Paolo Bonzini wrote: > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index dc04bc767865..ff17849be9f4 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1768,40 +1768,6 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) > return false; > } > > -bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) > -{ > - kvm_pfn_t pfn = pte_pfn(range->arg.pte); > - > - if (!kvm->arch.mmu.pgt) > - return false; > - > - WARN_ON(range->end - range->start != 1); > - > - /* > - * If the page isn't tagged, defer to user_mem_abort() for sanitising > - * the MTE tags. The S2 pte should have been unmapped by > - * mmu_notifier_invalidate_range_end(). > - */ > - if (kvm_has_mte(kvm) && !page_mte_tagged(pfn_to_page(pfn))) > - return false; > - > - /* > - * We've moved a page around, probably through CoW, so let's treat > - * it just like a translation fault and the map handler will clean > - * the cache to the PoC. > - * > - * The MMU notifiers will have unmapped a huge PMD before calling > - * ->change_pte() (which in turn calls kvm_set_spte_gfn()) and > - * therefore we never need to clear out a huge PMD through this > - * calling path and a memcache is not required. > - */ > - kvm_pgtable_stage2_map(kvm->arch.mmu.pgt, range->start << PAGE_SHIFT, > - PAGE_SIZE, __pfn_to_phys(pfn), > - KVM_PGTABLE_PROT_R, NULL, 0); > - > - return false; > -} > - > bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) > { > u64 size = (range->end - range->start) << PAGE_SHIFT; Thanks. It's nice to see this code retire: Acked-by: Will Deacon Also, if you're in the business of hacking the MMU notifier code, it would be really great to change the .clear_flush_young() callback so that the architecture could handle the TLB invalidation. At the moment, the core KVM code invalidates the whole VMID courtesy of 'flush_on_ret' being set by kvm_handle_hva_range(), whereas we could do a much lighter-weight and targetted TLBI in the architecture page-table code when we actually update the ptes for small ranges. Will