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Wysocki" , Len Brown , Saket Dumbre , Paolo Bonzini , Jonathan Cameron , Chengwen Feng , Leonardo Bras , Kees Cook , =?UTF-8?q?Miko=C5=82aj=20Lenczewski?= , James Morse , Zeng Heng , mrigendrachaubey , Thomas Huth , Ryan Roberts , Yeoreum Yun , Mark Brown , Kevin Brodsky , James Clark , Fuad Tabba , Raghavendra Rao Ananta , Lorenzo Pieralisi , Sascha Bischoff , Anshuman Khandual , Tian Zheng Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-acpi@vger.kernel.org, acpica-devel@lists.linux.dev, kvm@vger.kernel.org Subject: [PATCH v2 09/13] KVM: arm64: Dirty-bitmap: avoid splitting previously split blocks Date: Mon, 29 Jun 2026 12:17:57 +0100 Message-ID: <20260629111820.1873540-10-leo.bras@arm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260629111820.1873540-1-leo.bras@arm.com> References: <20260629111820.1873540-1-leo.bras@arm.com> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2190; i=leo.bras@arm.com; h=from:subject; bh=lJewvoJDgRAUeWkoRNdtBdiHG+qUJ6Z9V/0pehqjb+M=; b=owGbwMvMwCX2pizjszvTwvWMp9WSGLKcQhKd1zM82ekWx5uge27fZO4PZWqWDzsnNGwuSDB7w XfrtqJGRykLgxgXg6yYIovso/mreL5PyThy5ccCmDmsTCBDGLg4BWAiLbMZ/sfNnvlxg8SMUr43 Vb+rP/q3Oqz1dtW6+7/nwh7v81svSL9lZOiWnMRZH6I0faGF3qlwyWlc+5wTix7knu5V+aRxeWW lFC8A X-Developer-Key: i=leo.bras@arm.com; a=openpgp; fpr=36E6C95AE0F111CC5B6F4D2E688C33F8A0C5B0C5 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260629_041912_742493_AD8691A4 X-CRM114-Status: GOOD ( 12.06 ) 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 If previous dirty-clean already split a block, then avoid calling the split helper on that block again. Signed-off-by: Leonardo Bras --- arch/arm64/kvm/dirty_bit.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/dirty_bit.c b/arch/arm64/kvm/dirty_bit.c index d05af3de78be..6c928677ce12 100644 --- a/arch/arm64/kvm/dirty_bit.c +++ b/arch/arm64/kvm/dirty_bit.c @@ -153,20 +153,21 @@ int __kvm_arch_dirty_log_clear(struct kvm *kvm, bool *flush) { int ret = 0; int idx = 0; unsigned long *dirty_bitmap = memslot->dirty_bitmap; u64 *hw_entries; const int entries_sz = PAGE_SIZE / sizeof(*hw_entries); u64 ttwl; u64 start, end; gfn_t base_gfn; + gpa_t split_end = 0; hw_entries = kmalloc_objs(u64, entries_sz, GFP_KERNEL); if (!hw_entries) return -ENOMEM; ttwl = HDBSS_ENTRY_TTWL(KVM_PGTABLE_LAST_LEVEL); if (log) { start = log->first_page / BITS_PER_LONG; end = start + DIV_ROUND_UP(log->num_pages, BITS_PER_LONG); @@ -197,24 +198,28 @@ int __kvm_arch_dirty_log_clear(struct kvm *kvm, mask = xchg(&dirty_bitmap[i], 0); bitmap[i] = mask; } if (!mask) continue; offset = base_gfn + i * BITS_PER_LONG; - if (kvm_dirty_log_manual_protect_and_init_set(kvm)) - kvm_mmu_split_huge_pages(kvm, - gfn_to_gpa(offset + __ffs(mask)), - gfn_to_gpa(offset + __fls(mask) + 1)); + if (kvm_dirty_log_manual_protect_and_init_set(kvm) && + (offset + BITS_PER_LONG > split_end)) { + gpa_t start = gfn_to_gpa(offset + __ffs(mask)); + gpa_t end = gfn_to_gpa(offset + __fls(mask) + 1); + + kvm_mmu_split_huge_pages(kvm, start, end); + split_end = gpa_to_gfn(ALIGN_DOWN(end, PMD_SIZE) + PMD_SIZE - 1); + } do { idx = mask_to_hdbss(&mask, hw_entries, offset, ttwl, idx, entries_sz); if (idx >= entries_sz) { ret = dirty_bit_clear(kvm, hw_entries, idx); *flush = *flush || ret > 0; if (ret != idx) { /* Save bits not converted back to bitmap */ atomic_long_or(mask, (atomic_long_t *)&dirty_bitmap[i]); goto out_err; -- 2.54.0