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spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=24pmGxp0BerDJEL+YDC3N+sa7h06Stj99ioR95Iibs4=; b=5C9tYQ4LSPnVsw KswY9+S1OoCWMqWAEeIBtQr++IMK7xk8UtXyE+7zV8y0IWskIuWKaFfU9RdtISjVBisXbyRr9GmP0 6+YMQL19ng8/dS/xPHWDS5HpGm4XexdL6Mr2Ozwj6J4krp+HqSq/7bbgkJtlciftQWybIz0IvOBzn 0ia+gk5AXRP6P/zYpEq/X5s/oXDmMuMI2vGW8jvJcxYzWKt/j+hholBMAuW0xNA9NMfYoG72P5boM y3lQiZ/2Xy42FJteMwFjLh7HEgPT1y0AuqhvrgqV/SaO4rnuQnz8o9OSajDuhRump2j68WCXYEinQ D8L2GlgT+Ptl3z7kmF3Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m5no9-00Cdr8-QS; Tue, 20 Jul 2021 11:21:05 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m5no5-00CdqA-4k for linux-arm-kernel@lists.infradead.org; Tue, 20 Jul 2021 11:21:02 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CE68B6113A; Tue, 20 Jul 2021 11:21:00 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1m5no2-00EUqR-Qa; Tue, 20 Jul 2021 12:20:58 +0100 Date: Tue, 20 Jul 2021 12:20:58 +0100 Message-ID: <87zguh8c4l.wl-maz@kernel.org> From: Marc Zyngier To: Quentin Perret Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, will@kernel.org, dbrazdil@google.com, Srivatsa Vaddagiri , Shanker R Donthineni , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: Re: [PATCH 03/16] KVM: arm64: Turn kvm_pgtable_stage2_set_owner into kvm_pgtable_stage2_annotate In-Reply-To: References: <20210715163159.1480168-1-maz@kernel.org> <20210715163159.1480168-4-maz@kernel.org> <871r7t9tgi.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: qperret@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, will@kernel.org, dbrazdil@google.com, vatsa@codeaurora.org, sdonthineni@nvidia.com, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210720_042101_287436_889F35F2 X-CRM114-Status: GOOD ( 25.13 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 20 Jul 2021 11:38:17 +0100, Quentin Perret wrote: > > On Tuesday 20 Jul 2021 at 11:21:17 (+0100), Marc Zyngier wrote: > > On Tue, 20 Jul 2021 11:09:21 +0100, > > Quentin Perret wrote: > > > > > > On Thursday 15 Jul 2021 at 17:31:46 (+0100), Marc Zyngier wrote: > > > > @@ -815,7 +807,7 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size, > > > > .arg = &map_data, > > > > }; > > > > > > > > - if (owner_id > KVM_MAX_OWNER_ID) > > > > + if (!annotation || (annotation & PTE_VALID)) > > > > return -EINVAL; > > > > > > Why do you consider annotation==0 invalid? The assumption so far has > > > been that the owner_id for the host is 0, so annotating a range with 0s > > > should be a valid operation -- this will be required when e.g. > > > transferring ownership of a page back to the host. > > > > How do you then distinguish it from an empty entry that doesn't map to > > anything at all? > > You don't, but that's beauty of it :) > > The host starts with a PGD full of zeroes, which in terms of ownership > means that it owns the entire (I)PA space. And it loses ownership of a > page only when we explicitly annotate it with an owner id != 0. Right. But this scheme doesn't apply to the guests, does it? Don't we need something that is non-null to preserve the table refcounting? Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel