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charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260327_073753_185314_955DC455 X-CRM114-Status: GOOD ( 22.74 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Mar 27, 2026 at 03:40:30PM +0800, Tian Zheng wrote: > > On 3/26/2026 2:20 AM, Leonardo Bras wrote: > > FEAT_HDBSS speeds up guest memory dirty tracking by avoiding a page fault > > and saving the entry in a tracking structure. > > > > That may be a problem when we have guest memory backed by hugepages or > > transparent huge pages, as it's not possible to do on-demand hugepage > > splitting, relying only on eager hugepage splitting. > > > > So, at stage2 initialization, enable eager hugepage splitting with > > chunk = PAGE_SIZE if the system supports HDBSS. > > > > Signed-off-by: Leonardo Bras > > --- > > arch/arm64/kvm/mmu.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > > index 070a01e53fcb..bdfa72b7c073 100644 > > --- a/arch/arm64/kvm/mmu.c > > +++ b/arch/arm64/kvm/mmu.c > > @@ -993,22 +993,26 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t > > mmu->last_vcpu_ran = alloc_percpu(typeof(*mmu->last_vcpu_ran)); > > if (!mmu->last_vcpu_ran) { > > err = -ENOMEM; > > goto out_destroy_pgtable; > > } > > for_each_possible_cpu(cpu) > > *per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1; > > - /* The eager page splitting is disabled by default */ > > - mmu->split_page_chunk_size = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT; > > + /* The eager page splitting is disabled by default if system has no HDBSS */ > > + if (system_supports_hacdbs()) > > + mmu->split_page_chunk_size = PAGE_SIZE; > > + else > > + mmu->split_page_chunk_size = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT; > > + > > mmu->split_page_cache.gfp_zero = __GFP_ZERO; > > mmu->pgd_phys = __pa(pgt->pgd); > > if (kvm_is_nested_s2_mmu(kvm, mmu)) > > kvm_init_nested_s2_mmu(mmu); > > return 0; > > out_destroy_pgtable: > > > Thanks again for sending this patch. I'll integrate it into the next version > and run some tests. > > Awesome, thanks! Leo