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Mon, 10 May 2021 13:49:25 +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 EBA82610CA; Mon, 10 May 2021 13:49:22 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) 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 1lg6Hh-000Rol-6X; Mon, 10 May 2021 14:49:21 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: James Morse , Suzuki K Poulose , Alexandru Elisei , Eric Auger , Hector Martin , Mark Rutland , kernel-team@android.com Subject: [PATCH v3 3/9] KVM: arm64: vgic: Be tolerant to the lack of maintenance interrupt Date: Mon, 10 May 2021 14:48:18 +0100 Message-Id: <20210510134824.1910399-4-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210510134824.1910399-1-maz@kernel.org> References: <20210510134824.1910399-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, eric.auger@redhat.com, marcan@marcan.st, mark.rutland@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-20210510_064923_284062_39B265D3 X-CRM114-Status: GOOD ( 18.08 ) 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 As it turns out, not all the interrupt controllers are able to expose a vGIC maintenance interrupt as a distrete signal. And to be fair, it doesn't really matter as all we require is for *something* to kick us out of guest mode out way or another. On systems that do not expose a maintenance interrupt as such, there are two outcomes: - either the virtual CPUIF does generate an interrupt, and by the time we are back to the host the interrupt will have long been disabled (as we set ICH_HCR_EL2.EN to 0 on exit). In this case, interrupt latency is as good as it gets. - or some other event (physical timer) will take us out of the guest anyway, and the only drawback is a bad interrupt latency. So let's be tolerant to the lack of maintenance interrupt, and just let the user know that their mileage may vary... Signed-off-by: Marc Zyngier --- arch/arm64/kvm/vgic/vgic-init.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c index 2fdb65529594..9fd23f32aa54 100644 --- a/arch/arm64/kvm/vgic/vgic-init.c +++ b/arch/arm64/kvm/vgic/vgic-init.c @@ -524,11 +524,6 @@ int kvm_vgic_hyp_init(void) if (!gic_kvm_info) return -ENODEV; - if (!gic_kvm_info->maint_irq) { - kvm_err("No vgic maintenance irq\n"); - return -ENXIO; - } - switch (gic_kvm_info->type) { case GIC_V2: ret = vgic_v2_probe(gic_kvm_info); @@ -552,6 +547,11 @@ int kvm_vgic_hyp_init(void) if (ret) return ret; + if (!kvm_vgic_global_state.maint_irq) { + kvm_err("No maintenance interrupt available, fingers crossed...\n"); + return 0; + } + ret = request_percpu_irq(kvm_vgic_global_state.maint_irq, vgic_maintenance_handler, "vgic", kvm_get_running_vcpus()); -- 2.29.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel