From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 27B16CD8C9D for ; Mon, 8 Jun 2026 16:33:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=IvBqSXhSd0+ciY4t6uSyUxq+YGf55pIi3P3ho2un0FY=; b=xaxyXq0Qemn4Xvlrs9qSl1HMgC CP5miV1kzCs6YZ5hEQ3sYFu73tBiSSRAqku7F32qSbufoeIyH3OrKMwFoPEv+7c+eka+Zp/PADdR/ HJaMGk44Famh+jLOMYb6AEV97Pz/Yr941UeNJXCaWQoCQbtUkqV4eAnEvKgbJVSSV5IyQfoYf78OS /49RJ114Pe4cxD+tUawCPTLRfLvqpQ7DL3qeUOBkrkeboPELNCRFGliqITbyVhq2Vg+gfCKE6+Sds C/l3gSszFrcQ2TnCXYqQLbH+uR6E7BayiWCjz6Z0qwArPlhkMfiR+w2OO+bVtc0Aeq0hTDosxHpYK MPziTgKA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wWcv4-000000045CE-0jbB; Mon, 08 Jun 2026 16:33:46 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wWcv3-000000045C7-1VSv for linux-arm-kernel@lists.infradead.org; Mon, 08 Jun 2026 16:33:45 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id CB6F060098; Mon, 8 Jun 2026 16:33:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6411B1F00893; Mon, 8 Jun 2026 16:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780936424; bh=IvBqSXhSd0+ciY4t6uSyUxq+YGf55pIi3P3ho2un0FY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Lk9Z4YocwsJ6/Lori8Zu06XkPFHAr+wuediCAZhdXunEpVhN+HkMFp+DF2an6tK+k 5QrEervLDBN/4F+qxGk3DXJ8jb5EG8wQjjrz7GPkkXDar1LikvH6jMLoir8x4WKwjB 9GBInAU4XfCeebAYA1GI1/CeTDWOa9REaCp3JojCjFfeix1yRIgCn2f1FJ6fBtvAPo bcAIlnoHxlyraPq4iPG241VyQat3Udacw2BG+xRjfCM8nqlyK7e+Yy5WigpLhNhSC3 RG9OpQzgWv5L9Hgkz3cQZS7UTO7FN4o2E0xW5iZzS8pFS5d102JEdzurf51Zo2lvlO s3fbvfeqbMPNw== Date: Mon, 8 Jun 2026 09:33:43 -0700 From: Oliver Upton To: Marc Zyngier Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Steffen Eiden , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Hyunwoo Kim , stable@vger.kernel.org Subject: Re: [PATCH] KVM: arm64: Add kvm_for_each_vncr_tlb() helper Message-ID: References: <20260607175745.297793-1-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260607175745.297793-1-maz@kernel.org> 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 Hey Marc, Especially since this is a stable-worthy fix, it might be worth calling out the bug in the shortlog, e.g. KVM: arm64: nv: Avoid dereferencing NULL VNCR pseudo-TLB On Sun, Jun 07, 2026 at 06:57:45PM +0100, Marc Zyngier wrote: > VNCR TLB invalidation occurs from MMU notifiers or TLBI instructions, > and either can race against a vcpu not being onlined yet (no pseudo-TLB > allocated). Similarly, the TLB might be invalid, and the invalidation > should be skipped in this case. > > Both kvm_invalidate_vncr_ipa() and kvm_invalidate_vncr_va() are > expected to perform the same checks, except that the latter doesn't > check for the allocation and blindly dereferences the pointer. > > Solve this by introducing a new iterator built on top of the usual > kvm_for_each_vcpu() that checks for both of the above conditions, > and convert the two users to it. > > Reported-by: Hyunwoo Kim > Signed-off-by: Marc Zyngier > Link: https://lore.kernel.org/r/aiUvSbrWndQeUPc8@v4bel > Fixes: 4ffa72ad8f37 ("KVM: arm64: nv: Add S1 TLB invalidation primitive for VNCR_EL2") > Cc: stable@vger.kernel.org Looks good Reviewed-by: Oliver Upton Thanks, Oliver > --- > arch/arm64/kvm/nested.c | 36 +++++++++++++++--------------------- > 1 file changed, 15 insertions(+), 21 deletions(-) > > diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c > index f8d3f3a723282..690b8e8564166 100644 > --- a/arch/arm64/kvm/nested.c > +++ b/arch/arm64/kvm/nested.c > @@ -908,9 +908,21 @@ static void invalidate_vncr(struct vncr_tlb *vt) > clear_fixmap(vncr_fixmap(vt->cpu)); > } > > +/* > + * VNCR TLB invalidation occurs from MMU notifiers or TLBI instructions, and > + * either can race against a vcpu not being onlined yet (no pseudo-TLB > + * allocated). Similarly, the TLB might be invalid. Skip those, as they > + * obviously don't participate in the invalidation at this stage. > + */ > +#define kvm_for_each_vncr_tlb(idx, vcpup, tlbp, kvm) \ > + kvm_for_each_vcpu(idx, vcpup, kvm) \ > + if (((tlbp) = vcpup->arch.vncr_tlb) && \ > + (tlbp)->valid) > + > static void kvm_invalidate_vncr_ipa(struct kvm *kvm, u64 start, u64 end) > { > struct kvm_vcpu *vcpu; > + struct vncr_tlb *vt; > unsigned long i; > > lockdep_assert_held_write(&kvm->mmu_lock); > @@ -918,24 +930,9 @@ static void kvm_invalidate_vncr_ipa(struct kvm *kvm, u64 start, u64 end) > if (!kvm_has_feat(kvm, ID_AA64MMFR4_EL1, NV_frac, NV2_ONLY)) > return; > > - kvm_for_each_vcpu(i, vcpu, kvm) { > - struct vncr_tlb *vt = vcpu->arch.vncr_tlb; > + kvm_for_each_vncr_tlb(i, vcpu, vt, kvm) { > u64 ipa_start, ipa_end, ipa_size; > > - /* > - * Careful here: We end-up here from an MMU notifier, > - * and this can race against a vcpu not being onlined > - * yet, without the pseudo-TLB being allocated. > - * > - * Skip those, as they obviously don't participate in > - * the invalidation at this stage. > - */ > - if (!vt) > - continue; > - > - if (!vt->valid) > - continue; > - > ipa_size = ttl_to_size(pgshift_level_to_ttl(vt->wi.pgshift, > vt->wr.level)); > ipa_start = vt->wr.pa & ~(ipa_size - 1); > @@ -965,17 +962,14 @@ static void invalidate_vncr_va(struct kvm *kvm, > struct s1e2_tlbi_scope *scope) > { > struct kvm_vcpu *vcpu; > + struct vncr_tlb *vt; > unsigned long i; > > lockdep_assert_held_write(&kvm->mmu_lock); > > - kvm_for_each_vcpu(i, vcpu, kvm) { > - struct vncr_tlb *vt = vcpu->arch.vncr_tlb; > + kvm_for_each_vncr_tlb(i, vcpu, vt, kvm) { > u64 va_start, va_end, va_size; > > - if (!vt->valid) > - continue; > - > va_size = ttl_to_size(pgshift_level_to_ttl(vt->wi.pgshift, > vt->wr.level)); > va_start = vt->gva & ~(va_size - 1); > -- > 2.47.3 >