From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=217.140.110.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793981579; b=Jxts5Cp6wWr2M+S/SXk/kLqsZJ//HNWfZswcJanXfj3nOc9/tb7NhMqwmRIfFdGys4xx VvekDCmcI+a/af/0XF/jDSLu1oKDr3wgHWn2p3BL3j8Tp5bF532K1pOY0+CJuvVB1VJ9z dMbrlL0ADmyYE0YcS3wbQ0NtaJQ8OE4et8LzwpXa1KkOQDy2AriHZ7ebJ8Kn2Yn3rqJAq sR7xlhi2w4vc5HvPKkaLqAiK+kx23wZhOH46QADlXjWszAdvAyeOU0NLRtlFnVkHasXih T//NVbZFY902cjwgWwUbHWoNkupaBWW+MpIwvt0NaAYfQnZxHX1yNJQ34wI0MTWFU+Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793981579; h=DMARC-Filter:Received:Received:DKIM-Signature:From:To:Cc:Subject: Date:Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: X-Developer-Signature:X-Developer-Key:Content-Transfer-Encoding; bh=IUG0dDHj/Zm5K5qiyoTo+dRTmDhIG43OjUhDi38YRoU=; b=NgHUpyWcrJLxb8Nwz4N7a0sw6v6GjSRyWlF45bvCt5mni0BUaS2u3ADDyRV9hLHyiGw0 NkD9qi0C7b8vVnSEMSoquhVJN/P32UviQuJxyjKRlnbsR7wFiIOGwkT1AnZFZCkhupzZ5 Cxyb46YhBmB2SkKcT5Tb60yfQnSMKFauFpyOQcdy2z0AknJYUzRzuD3oHlz31Gk38WWjX JZviuzd1Gefmtb3ce9LTYDwiNqlp2pbsXx6vM0KGT0Cx+cKPFiovL+jZMTTjMvmV/vogu t0mZhKOa1+KXd61NZhDg6Twxg2FRXx8VooisQ/7THBNcmepiT2BOxrU3DgQr7xdhNHw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=fdUE5Vpd; arc=none smtp.remote-ip=217.140.110.172 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 907B7606BF88 for ; Fri, 6 Nov 2026 16:12:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 907B7606BF88 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, unprotected) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=fdUE5Vpd 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 EF23D143D; Fri, 6 Nov 2026 08:12:54 -0800 (PST) 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 22A913F673; Fri, 6 Nov 2026 08:12:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1793981578; bh=Hl+8S3N2mqoCQjLHJajTSd+0DIMoIu1+UBhREoQ7E5E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fdUE5VpdaBYyeZvbjF77BnX40+05r2+gHOZ2gF5nxxwtnjdGCfA88LWUgwsTBIyco Rd7DYlbOZtZYSNtDSR5tuf2PW6rm7sZXAzlb7/jXBYjApE+5aws3LF7VHgs93d842H Xiy9eiiO6qt/AUbV6nyYY3sTMly4az30BW2MYzc4= From: Leonardo Bras To: Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Mark Rutland , Leonardo Bras , Raghavendra Rao Ananta Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH RESEND v4 3/3] KVM: arm64: Make stage2_split_walker() skip unnecessary walks Date: Fri, 6 Nov 2026 16:12:38 +0000 Message-ID: <20261106161240.1345126-4-leo.bras@arm.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261106161240.1345126-1-leo.bras@arm.com> References: <20261106161240.1345126-1-leo.bras@arm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1489; i=leo.bras@arm.com; h=from:subject; bh=Hl+8S3N2mqoCQjLHJajTSd+0DIMoIu1+UBhREoQ7E5E=; b=owGbwMvMwCX2pizjszvTwvWMp9WSGLLe/ilTv+wk3vxgW8skn89LuiSUZWMfvgt2rDxp/XxRa tCV0hyVjlIWBjEuBlkxRRbZR/NX8XyfknHkyo8FMHNYmUCGMHBxCsBE0ncwMrz2LGpq32RUkXKN ++b6nElLfnlHKGldTZjFaSZbzqQ29zjD//K3Oj8K3Ra9Sq11mvxq7batm4zEI+7HLlq94NXDaSG WBfwA X-Developer-Key: i=leo.bras@arm.com; a=openpgp; fpr=36E6C95AE0F111CC5B6F4D2E688C33F8A0C5B0C5 Content-Transfer-Encoding: 8bit Currently, when splitting, all the child nodes will be walked, with the walker just returning earlier if there is nothing to do. This means all pagetable entries in the splitting range get a callback from the walker function, even if it was a level-3 entry. Optimize splitting by skipping all level-3 entries, as they are already the smallest block size and can't be split any further. (i.e. set flag KVM_PGTABLE_WALK_SKIP_LEVEL3) Signed-off-by: Leonardo Bras --- arch/arm64/kvm/hyp/pgtable.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 80744478c810..f75cb666a103 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -1565,21 +1565,22 @@ static int stage2_split_walker(const struct kvm_pgtable_visit_ctx *ctx, new = kvm_init_table_pte(childp, mm_ops); stage2_make_pte(ctx, new); return 0; } int kvm_pgtable_stage2_split(struct kvm_pgtable *pgt, u64 addr, u64 size, struct kvm_mmu_memory_cache *mc) { struct kvm_pgtable_walker walker = { .cb = stage2_split_walker, - .flags = KVM_PGTABLE_WALK_LEAF, + .flags = KVM_PGTABLE_WALK_LEAF | + KVM_PGTABLE_WALK_SKIP_LEVEL3, .arg = mc, }; int ret; ret = kvm_pgtable_walk(pgt, addr, size, &walker); dsb(ishst); return ret; } int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu, -- 2.55.0