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 1069CCD5BD2 for ; Fri, 29 May 2026 07:43:59 +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:Content-Type:Cc:To:From: Subject:Message-ID:References:Mime-Version:In-Reply-To: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=u7WGxRyEbovaCEk6n++MhLN9S+efqVE7Q4ikibcd+yY=; b=Nu0JwkoyVatDUnvk0oS7kkmCZp cWV2TLKILEjWtLsIOATQ6+4P7k2WHIbT0mM2vupSiTwHIp1CSqLsHtZ6hXpRQBuzIMEtdu+M9pN6O 3oK+C1ZbYV80lOO/FO69TvPFOWx/DvJdfBOINoIdMs0o6XKn4AWri/15OfOko8wz5uunipj3Gq2I7 gApXX6/pErFT93cqV/jEIfHbLuZiNbnm56GNDpOfD2SowNOD+cxGmb7JPuP05XDfzA3dWtZaJJCtF rfjuqbx2D1GaS2eNgMlWnNass7vd24QcmikpiUZ7/WPLvglaGwM3+UMvLPBaXFikhV5SBnwqadcgo flg4R+7g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wSrsn-00000006tm3-0MEf; Fri, 29 May 2026 07:43:53 +0000 Received: from mail-wr1-x449.google.com ([2a00:1450:4864:20::449]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wSrsh-00000006tkF-17Kh for linux-arm-kernel@lists.infradead.org; Fri, 29 May 2026 07:43:48 +0000 Received: by mail-wr1-x449.google.com with SMTP id ffacd0b85a97d-449b2a183d3so8556886f8f.0 for ; Fri, 29 May 2026 00:43:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780040625; x=1780645425; darn=lists.infradead.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=u7WGxRyEbovaCEk6n++MhLN9S+efqVE7Q4ikibcd+yY=; b=sdoUgssS6sT1gddV5ErStLcpHVRDUEaOJkoJ0AkedFOIvGPxB0RDJIRV3QKJv9AzbG QRAoNG5hkCHuBG43AmmYeJ4EHo/tdCCjDvb6iUMd/qHud3Po4tWy+bZVVSMZS4WC2A/y iageNxcVphsI8Op262idO/ZyF2LnAb4jrNNmOa/JlsjySz3U1lcrTeg0HVbHt1z/70W+ 7Vyh8NCgAU7WUtbK2l7TepWCQF5c+WRSyPVbq0SHmpRDYBQz+OsjyTnmyL9nlz2jHJ+n PubTG0wT34VXB0aXsezsDsROx/j9xSyq8Yz2TOYEzjFzIMmew2FL850p0vQGKqcVBlHd MKTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780040625; x=1780645425; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=u7WGxRyEbovaCEk6n++MhLN9S+efqVE7Q4ikibcd+yY=; b=Eqs50TpJVQ+YxKW3psndBXN/4Q3hbfspw8tcjambu/yWZ9s+iQQNDTHiUHL0xo9sqr BS7/6EOH8C3dPuUHsWiu4GjdtaZIEGfDtUvFSmvzE0zrTCoB2DnX9H+DuQ3RI3tiCpFi iak4EcX3tqjXPgaO853GUU4oPkOwEi74RUIEgZFPW5IImWYCvPPzGrdTVCtpHJfH35// pctrpb2ThZakl9li2Fu1wM8+JBoc9XP6uEO83gmuexLiHxAgWHXmcevP50BdIx5VeKq0 tC6q/BRm20mC78sTr6r/6DoaXm7/AqnC5o+PxfORkBlq3r7ja3u6Vz4BagGKTeWzXu4Z I4vA== X-Gm-Message-State: AOJu0YzGm/w8eWlYWAm4yi8L3CI58S7RU5K4BYnjpu68jPl0TQ8Ydl1N Zd73YKqCVXgws1CH11e/oh8IJJfpqNd5O38I3drXFh1jJjpYq0P0Iajg/Qad481VYZ1Akyg7kg/ Gwg== X-Received: from wrzf10.prod.google.com ([2002:a05:6000:1b0a:b0:450:e76e:87e1]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:4683:b0:453:9897:76aa with SMTP id ffacd0b85a97d-45ef1385c29mr1854131f8f.21.1780040624606; Fri, 29 May 2026 00:43:44 -0700 (PDT) Date: Fri, 29 May 2026 08:43:41 +0100 In-Reply-To: <20260529074341.2271950-1-tabba@google.com> Mime-Version: 1.0 References: <20260529074341.2271950-1-tabba@google.com> X-Mailer: git-send-email 2.54.0.929.g9b7fa37559-goog Message-ID: <20260529074341.2271950-3-tabba@google.com> Subject: [PATCH 2/2] KVM: arm64: Avoid host/hyp share desync on unshare hypercall failure From: tabba@google.com To: Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Quentin Perret , Vincent Donnefort Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260529_004347_328564_6B27D96B X-CRM114-Status: GOOD ( 11.55 ) 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 unshare_pfn_hyp() erases the tracking node from hyp_shared_pfns and frees it before invoking __pkvm_host_unshare_hyp. If the hypercall fails (e.g. EL2 refcount still held, or page-state mismatch), the host loses its record while EL2 still holds the share, breaking later share/unshare attempts on the same pfn. Invoke the hypercall first; erase and free only on success. Fixes: 52b28657ebd7 ("KVM: arm64: pkvm: Unshare guest structs during teardown") Reported-by: Sashiko (local):gemini-3.1-pro Signed-off-by: Fuad Tabba --- arch/arm64/kvm/mmu.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 4a928fb003ff..8026e834528d 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -524,13 +524,17 @@ static int unshare_pfn_hyp(u64 pfn) goto unlock; } - this->count--; - if (this->count) + if (this->count > 1) { + this->count--; + goto unlock; + } + + ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn); + if (ret) goto unlock; rb_erase(&this->node, &hyp_shared_pfns); kfree(this); - ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn); unlock: mutex_unlock(&hyp_shared_pfns_lock); -- 2.54.0.929.g9b7fa37559-goog