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Sat, 05 Sep 2020 14:16:07 +0100 Date: Sat, 05 Sep 2020 14:16:06 +0100 Message-ID: <874kocmkix.wl-maz@kernel.org> From: Marc Zyngier To: Jonathan Cameron Subject: Re: [PATCH 22/23] KVM: arm64: Add a rVIC/rVID in-kernel implementation In-Reply-To: <20200904170036.00003bda@Huawei.com> References: <20200903152610.1078827-1-maz@kernel.org> <20200903152610.1078827-23-maz@kernel.org> <20200904170036.00003bda@Huawei.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 EasyPG/1.0.0 Emacs/26.3 (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: 185.104.136.29 X-SA-Exim-Rcpt-To: Jonathan.Cameron@Huawei.com, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, lorenzo.pieralisi@arm.com, suzuki.poulose@arm.com, Christoffer.Dall@arm.com, james.morse@arm.com, kernel-team@android.com, julien.thierry.kdev@gmail.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-20200905_091610_868653_65D1DEE2 X-CRM114-Status: GOOD ( 20.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo Pieralisi , kvm@vger.kernel.org, Suzuki K Poulose , Christoffer Dall , James Morse , Julien Thierry , kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org 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 Fri, 04 Sep 2020 17:00:36 +0100, Jonathan Cameron wrote: > > On Thu, 3 Sep 2020 16:26:09 +0100 > Marc Zyngier wrote: [...] > > +static int rvic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr) > > +{ > > + struct rvic_vm_data *data; > > + struct kvm_vcpu *vcpu; > > + u32 __user *uaddr, val; > > + u16 trusted, total; > > + int i, ret = -ENXIO; > > + > > + mutex_lock(&dev->kvm->lock); > > + > > + switch (attr->group) { > > + case KVM_DEV_ARM_RVIC_GRP_NR_IRQS: > > + if (attr->attr) > > + break; > > + > > + if (dev->kvm->arch.irqchip_data) { > > + ret = -EBUSY; > > + break; > > + } > > + > > + uaddr = (u32 __user *)(uintptr_t)attr->addr; > > + if (get_user(val, uaddr)) { > > + ret = -EFAULT; > > + break; > > + } > > + > > + trusted = FIELD_GET(KVM_DEV_ARM_RVIC_GRP_NR_TRUSTED_MASK, val); > > + total = FIELD_GET(KVM_DEV_ARM_RVIC_GRP_NR_TOTAL_MASK, val); > > + if (total < trusted || trusted < 32 || total < 64 || > > + trusted % 32 || total % 32 || total > 2048) { > > As I read the spec, we need at least 32 untrusted. (R0058) > This condition seems to allow that if trusted = 64 and untrusted = 0 Well spotted. I think the following would capture the constraints correctly: if (total <= trusted || trusted < 32 || total < 64 || trusted % 32 || total % 32 || total > 2048) { On the other hand, I wonder if this code would gain from being directly written in terms of trusted/untrusted, rather than trusted/total. It could make the reading against the spec easier. 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