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 B75EA382F0A for ; Fri, 15 May 2026 19:59:17 +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=1778875159; cv=none; b=jRQKB0cgoXMxETTBapacEMMI0Z5AZHCbsI8xf3PGBCSbKuq6ueRxNcS5ZAGqeQdh9VemEJ7PVbivTy1uoqBdg0kd7+q8Nmy6uEms6816C8bx/69pTsBPGEQO2ppQ+3Kq1sXs/hwIy9zHiVB1yrmsh+xWhzB/kJ01pYrLT3vB+Qk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778875159; c=relaxed/simple; bh=MLrBcCQTVm2GGFB/nArGSMcQpOlEmTb/IoWr+JN4CXU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mESExxLpyZT8KwrnDRF5HrVk6e3lXa7a3f8RQqQqgyYEaUuMlPUwuEdnmkHPUqLV8WVQVTEy3zTqUGmuId5gesMqv4Tf9zQxzlCISZazVkASQe5362NXBgg3BBP/2JluRkU35/yceUPmGmUARtL+5QAmGk7F/qcvooev9Nuo0yQ= 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=BV/yx3tn; 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="BV/yx3tn" 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 0DC0035DE; Fri, 15 May 2026 12:59:12 -0700 (PDT) Received: from devkitleo.cambridge.arm.com (devkitleo.cambridge.arm.com [10.1.196.90]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4D99C3F85F; Fri, 15 May 2026 12:59:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1778875157; bh=MLrBcCQTVm2GGFB/nArGSMcQpOlEmTb/IoWr+JN4CXU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BV/yx3tnCe6ZLdabikR0MI+TPmsk56L4qbqSRn50Xc6o/qYZmsp+LnGQwk+9bu3Xj ZNcfxg2ZRSYKj9Any6zWhy8wdFCgRP3RRMy4511HxwpEl6uatwULP+EAikZlLEPRb1 ZG/Ap5R4stKXYaCtxz8xDnIsvTSfRKhLd6DyRAFM= From: Leonardo Bras To: Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Fuad Tabba , Leonardo Bras , Raghavendra Rao Ananta Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [RFC PATCH 1/2] KVM: arm64: Introduce S2 walker SKIP return options Date: Fri, 15 May 2026 20:59:02 +0100 Message-ID: <20260515195904.2466381-2-leo.bras@arm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260515195904.2466381-1-leo.bras@arm.com> References: <20260515195904.2466381-1-leo.bras@arm.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3257; i=leo.bras@arm.com; h=from:subject; bh=MLrBcCQTVm2GGFB/nArGSMcQpOlEmTb/IoWr+JN4CXU=; b=owGbwMvMwCX2pizjszvTwvWMp9WSGLLYS7/PeVrkt7qmcOH89kCd9yvY9j1Om7VckePVpD9ei xPDr1Yd7ihlYRDjYpAVU2SRfTR/Fc/3KRlHrvxYADOHlQlkCAMXpwBMZN1Thv9V2yJK1/Iac53P /lDoMj0imemzqH637jHWiScv3p71RqWL4RdTehR3dHX9zNb7/+Rnzil543PkxpT2dXkaqzqD1Kq W3GEGAA== X-Developer-Key: i=leo.bras@arm.com; a=openpgp; fpr=36E6C95AE0F111CC5B6F4D2E688C33F8A0C5B0C5 Content-Transfer-Encoding: 8bit Introduce S2 walker return values: - SKIP_CHILDREN: skip walking the children of the current node - SKIP_SIBLINGS: skip waling the siblings of the current node Also, modify __kvm_pgtable_visit() to fulfil the hing on above return values. Current walkers should not be impacted Signed-off-by: Leonardo Bras --- arch/arm64/kvm/hyp/pgtable.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 0c1defa5fb0f..4e43339522bb 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -12,20 +12,26 @@ #include struct kvm_pgtable_walk_data { struct kvm_pgtable_walker *walker; const u64 start; u64 addr; const u64 end; }; +/* Positive walker return values point levels to skip */ +enum walker_return{ + SKIP_CHILDREN = 1, + SKIP_SIBLINGS +}; + static bool kvm_pgtable_walk_skip_bbm_tlbi(const struct kvm_pgtable_visit_ctx *ctx) { return unlikely(ctx->flags & KVM_PGTABLE_WALK_SKIP_BBM_TLBI); } static bool kvm_pgtable_walk_skip_cmo(const struct kvm_pgtable_visit_ctx *ctx) { return unlikely(ctx->flags & KVM_PGTABLE_WALK_SKIP_CMO); } @@ -134,21 +140,21 @@ static bool kvm_pgtable_walk_continue(const struct kvm_pgtable_walker *walker, * update a PTE. In the context of a fault handler this is interpreted * as a signal to retry guest execution. * * Ignore the return code altogether for walkers outside a fault handler * (e.g. write protecting a range of memory) and chug along with the * page table walk. */ if (r == -EAGAIN) return walker->flags & KVM_PGTABLE_WALK_IGNORE_EAGAIN; - return !r; + return r >= 0; } static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data, struct kvm_pgtable_mm_ops *mm_ops, kvm_pteref_t pgtable, s8 level); static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data, struct kvm_pgtable_mm_ops *mm_ops, kvm_pteref_t pteref, s8 level) { enum kvm_pgtable_walk_flags flags = data->walker->flags; @@ -185,23 +191,29 @@ static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data, * into a newly installed or replaced table. */ if (reload) { ctx.old = READ_ONCE(*ptep); table = kvm_pte_table(ctx.old, level); } if (!kvm_pgtable_walk_continue(data->walker, ret)) goto out; - if (!table) { - data->addr = ALIGN_DOWN(data->addr, kvm_granule_size(level)); - data->addr += kvm_granule_size(level); + if (!table || ret >= SKIP_CHILDREN) { + u64 size; + + if (ret == SKIP_SIBLINGS) /* Skip siblings */ + size = kvm_granule_size(level - 1); + else /* Skip children */ + size = kvm_granule_size(level); + + data->addr = ALIGN_DOWN(data->addr, size) + size; goto out; } childp = (kvm_pteref_t)kvm_pte_follow(ctx.old, mm_ops); ret = __kvm_pgtable_walk(data, mm_ops, childp, level + 1); if (!kvm_pgtable_walk_continue(data->walker, ret)) goto out; if (ctx.flags & KVM_PGTABLE_WALK_TABLE_POST) ret = kvm_pgtable_visitor_cb(data, &ctx, KVM_PGTABLE_WALK_TABLE_POST); -- 2.54.0