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Tue, 28 May 2019 05:48:22 -0700 (PDT) Received: from [10.162.0.144] (a075553-lin.blr.arm.com [10.162.0.144]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A42393F5AF; Tue, 28 May 2019 05:48:19 -0700 (PDT) Subject: Re: [kvmtool PATCH v10 5/5] KVM: arm/arm64: Add a vcpu feature for pointer authentication To: Dave Martin References: <1555994558-26349-1-git-send-email-amit.kachhap@arm.com> <1555994558-26349-6-git-send-email-amit.kachhap@arm.com> <20190423154625.GP3567@e103592.cambridge.arm.com> <3b7bafc9-5d6a-7845-ef1f-577ea59000e2@arm.com> <20190424134120.GW3567@e103592.cambridge.arm.com> <20190528101128.GB28398@e103592.cambridge.arm.com> From: Amit Daniel Kachhap Message-ID: <53ecc253-e9e0-a6ca-2540-fa85bd26bfc1@arm.com> Date: Tue, 28 May 2019 18:18:16 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190528101128.GB28398@e103592.cambridge.arm.com> Content-Language: en-US Cc: Marc Zyngier , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Kristina Martsenko , Ramana Radhakrishnan , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Dave, On 5/28/19 3:41 PM, Dave Martin wrote: > On Wed, Apr 24, 2019 at 02:41:21PM +0100, Dave Martin wrote: >> On Wed, Apr 24, 2019 at 12:32:22PM +0530, Amit Daniel Kachhap wrote: >>> Hi, >>> >>> On 4/23/19 9:16 PM, Dave Martin wrote: > > [...] > >>>>> diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c >>>>> index 7780251..acd1d5f 100644 >>>>> --- a/arm/kvm-cpu.c >>>>> +++ b/arm/kvm-cpu.c >>>>> @@ -68,6 +68,18 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id) >>>>> vcpu_init.features[0] |= (1UL << KVM_ARM_VCPU_PSCI_0_2); >>>>> } >>>>> + /* Check Pointer Authentication command line arguments. */ >>>>> + if (kvm->cfg.arch.enable_ptrauth && kvm->cfg.arch.disable_ptrauth) >>>>> + die("Both enable-ptrauth and disable-ptrauth option cannot be present"); >>>> >>>> Preferably, print the leading dashes, the same as the user would see >>>> on the command line (e.g., --enable-ptrauth, --disable-ptrauth). >>>> >>>> For brevity, we could write something like: >>>> >>>> die("--enable-ptrauth conflicts with --disable-ptrauth"); > > [...] > >>>>> @@ -106,8 +118,12 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id) >>>>> die("Unable to find matching target"); >>>>> } >>>>> - if (err || target->init(vcpu)) >>>>> - die("Unable to initialise vcpu"); >>>>> + if (err || target->init(vcpu)) { >>>>> + if (kvm->cfg.arch.enable_ptrauth) >>>>> + die("Unable to initialise vcpu with pointer authentication feature"); >>>> >>>> We don't special-case this error message for any other feature yet: >>>> there are a variety of reasons why we might have failed, so suggesting >>>> that the failure is something to do with ptrauth may be misleading to >>>> the user. >>>> >>>> If we want to be more informative, we could do something like the >>>> following: >>>> >>>> bool supported; >>>> >>>> supported = kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_ADDRESS) && >>>> kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_GENERIC); >>>> >>>> if (kvm->cfg.arch.enable_ptrauth && !supported) >>>> die("--enable-ptrauth not supported on this host"); >>>> >>>> if (supported && !kvm->cfg.arch.disable_ptrauth) >>>> vcpu_init.features[0] |= ARM_VCPU_PTRAUTH_FEATURE; >>>> >>>> /* ... */ >>>> >>>> if (err || target->init(vcpu)) >>>> die("Unable to initialise vcpu"); >>>> >>>> We don't do this for any other feature today, but since it helps the >>>> user to understand what went wrong it's probably a good idea. >>> Yes this is more clear. As Mark has picked the core guest ptrauth patches. I >>> will post this changes as standalone. >> >> Sounds good. (I also need to do that separately for SVE...) > > Were you planning to repost this? > > Alternatively, I can fix up the diagnostic messages discussed here and > post it together with the SVE support. I'll do that locally for now, > but let me know what you plan to do. I'd like to get the SVE support > posted soon so that people can test it. I will clean up the print messages as you suggested and repost it shortly. Thanks, Amit Daniel > > Cheers > ---Dave > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm