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Wed, 21 Oct 2026 13:25:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792589155; bh=WmpDi7uAEvCBbE9BhvFq4d4HOMx3zfGqFapjUnsxTxk=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=RZozsfb0ChtozlH8YnpQ1cvLafomzdAOPmTu3pessHUZEoHJL/MrAJMGUyG8k2Mau qgjn7jTqXt/flSpYgcfX+K+u9Rtt6WTRs7nnerWzG+lfXX72yz43wL50iwsPPJKrPh BurJWL0QMxEcsoqIxUtGh4HAtd6ygCCv05wCx3XJJauqJvLEW0V63lsqzdFt27ODpX Bokboc/Fk0G5plek7tBZwQnuhWbTRETuZcb9Pj5zyr7bs7jcgE9MJKUJ/M4lp74nFi H/wgoVGnz/lXgpcr+1zIM6WvSB0oSKy/kghjSMMLpQeMDAOk9W6jXM6IEP6nRJj+rO O8gs8ipyhpcBg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1xJWKH-00000005cet-0YFY; Wed, 21 Oct 2026 13:25:53 +0000 Date: Wed, 21 Oct 2026 14:25:52 +0100 Message-ID: <86pkx3yylb.wl-maz@kernel.org> From: Marc Zyngier To: Vincent Donnefort Cc: oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, stable@vger.kernel.org Subject: Re: [PATCH v1] KVM: arm64: pkvm: Clear GICv3 LRs in the hypervisor In-Reply-To: References: <20261021110000.508827-1-vdonnefort@google.com> <86qzhjz1iz.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/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) X-Archived-By: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: vdonnefort@google.com, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, stable@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, 21 Oct 2026 13:50:22 +0100, Vincent Donnefort wrote: > > On Wed, Oct 21, 2026 at 01:22:28PM +0100, Marc Zyngier wrote: > > On Wed, 21 Oct 2026 12:00:00 +0100, > > Vincent Donnefort wrote: > > > > > > The LR registers are architecturally UNKNOWN when the CPU boots or > > > resumes. However, in protected mode, only the used ones are reset. > > > During boot the HVC __vgic_v3_init_lrs() is never called because > > > vgic_present is only set in init_subsystems(), after cpu_hyp_init() was > > > called. > > > > Why don't you fix this rather than making the init even more > > different? > > Ack, I'll make a patch to fix that first. > > > > > > Also, the PM notifier isn't registered for pKVM and the HVC > > > becomes unavailable after the host is deprivileged. > > > > Sanitising the LRs on PSCI_ON is probably the right thing to do, but I > > don't understand why resetting the LRs is out of reach from the host, > > given that the host is fully in charge of the interrupt injection, and > > therefore controls the LRs. > > I suppose I could reinstantiate the pm callbacks for pkvm to at least reset the > LRs? I think there are two different things: - pKVM must not rely on the host resetting the LRs once it is deprivileged (that's the PSCI_ON case) - pKVM must not prevent the host from resetting the LRs (that's the "mind your own business" case). Both need addressing. If that means the LRs get reset twice because pKVM inherits the PM callbacks, so be it. Thanks, M. -- Without deviation from the norm, progress is not possible.