From: Leonardo Bras <leo.bras@arm•com>
To: Tian Zheng <zhengtian10@huawei•com>
Cc: Leonardo Bras <leo.bras@arm•com>,
maz@kernel•org, oupton@kernel•org, catalin.marinas@arm•com,
corbet@lwn•net, pbonzini@redhat•com, will@kernel•org,
yuzenghui@huawei•com, wangzhou1@hisilicon•com,
liuyonglong@huawei•com, Jonathan.Cameron@huawei•com,
yezhenyu2@huawei•com, linuxarm@huawei•com, joey.gouly@arm•com,
kvmarm@lists•linux.dev, kvm@vger•kernel.org,
linux-arm-kernel@lists•infradead.org, linux-doc@vger•kernel.org,
linux-kernel@vger•kernel.org, skhan@linuxfoundation•org,
suzuki.poulose@arm•com
Subject: [PATCH] arm64/kvm: Enable eager hugepage splitting if HDBSS is available
Date: Wed, 25 Mar 2026 18:20:27 +0000 [thread overview]
Message-ID: <acQna2hLwdr1juTN@devkitleo> (raw)
In-Reply-To: <acQj5grOdZT8LUGp@devkitleo>
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 <leo.bras@arm•com>
---
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:
--
2.53.0
next prev parent reply other threads:[~2026-03-25 18:20 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-25 4:04 [PATCH v3 0/5] Support the FEAT_HDBSS introduced in Armv9.5 Tian Zheng
2026-02-25 4:04 ` [PATCH v3 1/5] arm64/sysreg: Add HDBSS related register information Tian Zheng
2026-02-25 4:04 ` [PATCH v3 2/5] KVM: arm64: Add support to set the DBM attr during memory abort Tian Zheng
2026-02-25 4:04 ` [PATCH v3 3/5] KVM: arm64: Add support for FEAT_HDBSS Tian Zheng
2026-06-01 0:50 ` Inochi Amaoto
2026-06-01 8:58 ` Marc Zyngier
2026-06-01 9:05 ` Inochi Amaoto
2026-06-05 8:29 ` Tian Zheng
2026-02-25 4:04 ` [PATCH v3 4/5] KVM: arm64: Enable HDBSS support and handle HDBSSF events Tian Zheng
2026-02-25 17:46 ` Leonardo Bras
2026-02-27 10:47 ` Tian Zheng
2026-02-27 14:10 ` Leonardo Bras
2026-03-04 3:06 ` Tian Zheng
2026-03-04 12:08 ` Leonardo Bras
2026-03-05 7:37 ` Tian Zheng
2026-03-04 15:40 ` Leonardo Bras
2026-03-06 9:27 ` Tian Zheng
2026-03-06 15:01 ` Leonardo Bras
2026-03-12 6:17 ` Tian Zheng
2026-03-12 12:06 ` Leonardo Bras
2026-03-12 13:13 ` Tian Zheng
2026-03-12 14:58 ` Leonardo Bras
2026-03-25 18:05 ` Leonardo Bras
2026-03-25 18:20 ` Leonardo Bras [this message]
2026-03-27 7:40 ` [PATCH] arm64/kvm: Enable eager hugepage splitting if HDBSS is available Tian Zheng
2026-03-27 14:37 ` Leonardo Bras
2026-03-26 14:31 ` [PATCH v3 4/5] KVM: arm64: Enable HDBSS support and handle HDBSSF events Leonardo Bras
2026-03-27 7:35 ` Tian Zheng
2026-03-27 15:00 ` Leonardo Bras
2026-03-28 6:05 ` Tian Zheng
2026-03-30 11:31 ` Leonardo Bras
2026-04-21 14:18 ` Leonardo Bras
2026-04-24 6:48 ` Tian Zheng
2026-04-24 10:08 ` Leonardo Bras
2026-02-25 4:04 ` [PATCH v3 5/5] KVM: arm64: Document HDBSS ioctl Tian Zheng
2026-03-31 14:13 ` [PATCH v3 0/5] Support the FEAT_HDBSS introduced in Armv9.5 Leonardo Bras
2026-04-02 2:40 ` Tian Zheng
2026-04-02 12:42 ` Leonardo Bras
2026-05-19 15:23 ` Will Deacon
2026-05-19 15:35 ` Leonardo Bras
2026-05-20 8:51 ` Tian Zheng
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