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From: Oliver Upton To: Raghavendra Rao Ananta Cc: Oliver Upton , Marc Zyngier , Ricardo Koller , Reiji Watanabe , James Morse , Alexandru Elisei , Suzuki K Poulose , Paolo Bonzini , Catalin Marinas , Will Deacon , Jing Zhang , Colton Lewis , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [RFC PATCH 4/6] KVM: arm64: Optimize TLBIs in the dirty logging path Message-ID: References: <20230109215347.3119271-1-rananta@google.com> <20230109215347.3119271-5-rananta@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230109215347.3119271-5-rananta@google.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230124_145412_280293_45AD9BF9 X-CRM114-Status: GOOD ( 17.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Raghavendra, I find the commit title rather ambiguous. May I suggest: KVM: arm64: Use range-based TLBIs for write protection On Mon, Jan 09, 2023 at 09:53:45PM +0000, Raghavendra Rao Ananta wrote: > Currently the dirty-logging paths, including > kvm_arch_flush_remote_tlbs_memslot() and kvm_mmu_wp_memory_region() > ivalidates the entire VM's TLB entries using kvm_flush_remote_tlbs(). > As the range of IPAs is provided by these functions, this is highly > inefficient on the systems which support FEAT_TLBIRANGE. Hence, > use kvm_flush_remote_tlbs_range() to flush the TLBs instead. This commit message gives a rather mechanical description of the commit. Instead of describing the change, could you describe _why_ this is an improvement over the VM-wide invalidation? -- Thanks, Oliver > Signed-off-by: Raghavendra Rao Ananta > --- > arch/arm64/kvm/arm.c | 7 ++++++- > arch/arm64/kvm/mmu.c | 2 +- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 00da570ed72bd..179520888c697 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -1433,7 +1433,12 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) > void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm, > const struct kvm_memory_slot *memslot) > { > - kvm_flush_remote_tlbs(kvm); > + phys_addr_t start, end; > + > + start = memslot->base_gfn << PAGE_SHIFT; > + end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT; > + > + kvm_flush_remote_tlbs_range(kvm, start, end); > } > > static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 70f76bc909c5d..e34b81f5922ce 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -976,7 +976,7 @@ static void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot) > write_lock(&kvm->mmu_lock); > stage2_wp_range(&kvm->arch.mmu, start, end); > write_unlock(&kvm->mmu_lock); > - kvm_flush_remote_tlbs(kvm); > + kvm_flush_remote_tlbs_range(kvm, start, end); > } > > /** > -- > 2.39.0.314.g84b9a713c41-goog > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel