From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 029CC45BD71; Wed, 29 Jul 2026 10:47:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785322025; cv=none; b=lhp9DyOvyNACOL2FSmzAfOWaDr66JcALHhGnRPtRmSX9m4SqvDdeLvmQz4xOIVd6wElHG3JmLr/LU//1wity4pvshH2a2MyA/XRQ/OlSixvEyMFOP44/atOyHpGcYGsy+qTod/GajTfi7BKylbK7yEKiHGrSib7FCdNJ9WYsHGQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785322025; c=relaxed/simple; bh=q8b/IF40I1EjZuCj1A0d+zd8jdpLqWvWNJRxKNN3/lQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=duIUu8hJ/aGsV4hCQa92AiFDvophZh/WkQP8DJFcLwZjcxUukRS4ME/d1/6Pf/4TjRAYLhMAzyAB7rqodw+v8zMtLCCJQRx2TUTLn4QQDyvHr3dRTiTKro+74JpN6g9oQfyhG6aUHZpUaLqb0XomVUSRxTcOxt7+eH7HlnoQH5I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=UqEE8O+2; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="UqEE8O+2" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 43FA9202C; Wed, 29 Jul 2026 03:46:59 -0700 (PDT) Received: from LeoBrasDK.cambridge.arm.com (LeoBrasDK.cambridge.arm.com [10.2.212.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7F2883F66F; Wed, 29 Jul 2026 03:46:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1785322023; bh=q8b/IF40I1EjZuCj1A0d+zd8jdpLqWvWNJRxKNN3/lQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UqEE8O+2ELBgIowNaCHrxKC18Fs6lH8FOQphvvvaKdtWBgcIQc+3G1bJecIW/R2m5 pNLhzFmPWaIli9F7XCj8+fzRRyrO3wccERiFpphCWaS4pkV0KwvGotDFHJpWR7SPEK 3saNPP4cy/+z0i/oEiUZd9/F0WF2VDvrExBd8gtY= From: Leonardo Bras To: Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Paolo Bonzini , James Morse , Leonardo Bras , Yang Shi , mrigendrachaubey , Thomas Huth , Zeng Heng , Ryan Roberts , Mark Brown , Sascha Bischoff , Yicong Yang , Kevin Brodsky , James Clark , Raghavendra Rao Ananta , Yeoreum Yun , Mark Rutland , Anshuman Khandual , Tian Zheng Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org Subject: [PATCH v3 10/11] KVM: arm64: Add hardware-accelerated dirty-ring cleaning routine Date: Wed, 29 Jul 2026 11:45:45 +0100 Message-ID: <20260729104548.3439958-11-leo.bras@arm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260729104548.3439958-1-leo.bras@arm.com> References: <20260729104548.3439958-1-leo.bras@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4468; i=leo.bras@arm.com; h=from:subject; bh=q8b/IF40I1EjZuCj1A0d+zd8jdpLqWvWNJRxKNN3/lQ=; b=owGbwMvMwCX2pizjszvTwvWMp9WSGLIyb17vnak+/9q0F3e3rfaPmcn55m9k1WOGI3OCKhq3W R96JG7q1lHKwiDGxSArpsgi+2j+Kp7vUzKOXPmxAGYOKxPIEAYuTgGYSOZ+hv8VpjLSR3+v5NrG c3CvgZbN3DUdcxTUQ4/pSkXvPew85/cZhv+Z0UcCp0uX1noqHexpLw056Lj2UNFxJsdlHzl2cev ZxXMAAA== X-Developer-Key: i=leo.bras@arm.com; a=openpgp; fpr=36E6C95AE0F111CC5B6F4D2E688C33F8A0C5B0C5 Content-Transfer-Encoding: 8bit Implement arm64 version of kvm_arch_dirty_ring_clear() making use of FEAT_HACDBS. It works by transversing the dirty-ring and converting its entries into HDBSS entries based on the slot offset. The resulting HDBSS array is then fed to the HACDBS mechanism that walks the pagetable marking writable-dirty pages as writable-clean. Only successfully cleaned entries are set as invalid on the dirty-ring, so in case of error, falling back to generic software cleaning will take care of any remaining entry in the dirty-ring. Signed-off-by: Leonardo Bras --- arch/arm64/include/asm/kvm_dirty_bit.h | 13 +++++ arch/arm64/kvm/dirty_bit.c | 77 ++++++++++++++++++++++++++ 2 files changed, 90 insertions(+) diff --git a/arch/arm64/include/asm/kvm_dirty_bit.h b/arch/arm64/include/asm/kvm_dirty_bit.h index d368a23a84b3..f785a7aad9e8 100644 --- a/arch/arm64/include/asm/kvm_dirty_bit.h +++ b/arch/arm64/include/asm/kvm_dirty_bit.h @@ -8,29 +8,42 @@ #define __ARM64_KVM_DIRTY_BIT_H__ #include int __kvm_arch_dirty_log_clear(struct kvm *kvm, struct kvm_memory_slot *memslot, struct kvm_clear_dirty_log *log, unsigned long *bitmap, bool *flush); +int __kvm_arch_dirty_ring_clear(struct kvm *kvm, struct kvm_dirty_ring *ring, + int *nr_entries_reset); + static inline bool kvm_arch_dirty_clear_enabled(struct kvm *kvm) { return system_supports_hacdbs() && kvm->arch.mmu.pgt && (kvm->arch.mmu.pgt->flags & KVM_PGTABLE_S2_DBM); } static inline int kvm_arch_dirty_log_clear(struct kvm *kvm, struct kvm_memory_slot *memslot, struct kvm_clear_dirty_log *log, unsigned long *bitmap, bool *flush) { if (!kvm_arch_dirty_clear_enabled(kvm)) return -EPERM; return __kvm_arch_dirty_log_clear(kvm, memslot, log, bitmap, flush); } +static inline int kvm_arch_dirty_ring_clear(struct kvm *kvm, + struct kvm_dirty_ring *ring, + int *nr_entries_reset) +{ + if (!kvm_arch_dirty_clear_enabled(kvm)) + return -EPERM; + + return __kvm_arch_dirty_ring_clear(kvm, ring, nr_entries_reset); +} + #endif /* __ARM64_KVM_DIRTY_BIT_H__ */ diff --git a/arch/arm64/kvm/dirty_bit.c b/arch/arm64/kvm/dirty_bit.c index d7e624f9b630..ca9cfefe0893 100644 --- a/arch/arm64/kvm/dirty_bit.c +++ b/arch/arm64/kvm/dirty_bit.c @@ -352,10 +352,87 @@ int __kvm_arch_dirty_log_clear(struct kvm *kvm, } ret = -EAGAIN; } write_unlock(&kvm->mmu_lock); kfree(hw_entries); return ret; } + +int __kvm_arch_dirty_ring_clear(struct kvm *kvm, struct kvm_dirty_ring *ring, + int *nr_entries_reset) +{ + u64 *hw_entries __free(kfree) = NULL; + u64 ttwl; + s64 cur_slot = S64_MAX; + int i, ret; + struct kvm_memory_slot *memslot; + + if (signal_pending(current)) + return -EINTR; + + ttwl = HDBSS_ENTRY_TTWL(KVM_PGTABLE_LAST_LEVEL); + + hw_entries = kmalloc(max(ring->size * sizeof(u64), PAGE_SIZE), GFP_KERNEL); + if (!hw_entries) + return -ENOMEM; + + for (i = 0; i < ring->size; i++) { + struct kvm_dirty_gfn *entry; + gfn_t gfn; + u32 entry_slot; + u64 entry_offset; + + entry = &ring->dirty_gfns[(ring->reset_index + i) & + (ring->size - 1)]; + + if (!kvm_dirty_gfn_harvested(entry)) + break; + + entry_slot = READ_ONCE(entry->slot); + entry_offset = READ_ONCE(entry->offset); + + if (entry_slot != cur_slot) { + memslot = kvm_dirty_ring_get_memslot(kvm, entry_slot); + if (!memslot) + return -EFAULT; + + cur_slot = entry_slot; + } + + if (entry_offset >= memslot->npages) + return -EFAULT; + + gfn = memslot->base_gfn + entry_offset; + + hw_entries[i] = (gfn_to_gpa(gfn) & HDBSS_ENTRY_IPA) | + ttwl | HDBSS_ENTRY_VALID; + } + + if (i == 0) + return 0; + + write_lock(&kvm->mmu_lock); + ret = dirty_bit_clear(kvm, hw_entries, i); + write_unlock(&kvm->mmu_lock); + + /* Set as invalid all successfully cleaned entries */ + for (int j = 0; j < ret; j++) { + struct kvm_dirty_gfn *entry; + + entry = &ring->dirty_gfns[(ring->reset_index + j) & + (ring->size - 1)]; + + kvm_dirty_gfn_set_invalid(entry); + } + + /* In case of error, try software cleaning from the faulting entry */ + ring->reset_index += ret; + *nr_entries_reset += ret; + + if (ret < i) + return -EAGAIN; + + return ret; +} -- 2.55.0