From: Amit Daniel Kachhap <amit.kachhap@arm.com> To: James Morse <james.morse@arm.com>, Kristina Martsenko <kristina.martsenko@arm.com> Cc: linux-arm-kernel@lists.infradead.org, Christoffer Dall <christoffer.dall@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Andrew Jones <drjones@redhat.com>, Dave Martin <Dave.Martin@arm.com>, Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>, Julien Thierry <julien.thierry@arm.com> Subject: Re: [PATCH v7 7/10] KVM: arm/arm64: context-switch ptrauth registers Date: Thu, 28 Mar 2019 16:59:17 +0530 [thread overview] Message-ID: <8c38a9fe-8310-4903-7042-e8b5eb3b5f1b@arm.com> (raw) In-Reply-To: <13ab02cf-db27-d604-6e5f-d276dec0779b@arm.com> Hi James, On 3/27/19 11:46 PM, James Morse wrote: > Hi Amit, Kristina, > > On 27/03/2019 03:21, Amit Daniel Kachhap wrote: >> On 3/26/19 11:31 PM, Kristina Martsenko wrote: >>> On 26/03/2019 04:03, Amit Daniel Kachhap wrote: >>>> On 3/26/19 1:34 AM, Kristina Martsenko wrote: >>>>> On 19/03/2019 08:30, Amit Daniel Kachhap wrote: >>>>>> From: Mark Rutland <mark.rutland@arm.com> >>>>>> >>>>>> When pointer authentication is supported, a guest may wish to use it. >>>>>> This patch adds the necessary KVM infrastructure for this to work, with >>>>>> a semi-lazy context switch of the pointer auth state. > >>>>>> + if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) || >>>>>> + test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features)) {>>>>> + /* Verify that KVM startup matches the conditions for ptrauth */ >>>>>> + if (WARN_ON(!vcpu_has_ptrauth(vcpu))) >>>>>> + return -EINVAL; >>>>>> + } > >>> One more thing - I think the WARN_ON() here should be removed. Otherwise >>> if panic_on_warn is set then userspace can panic the kernel. I think >>> WARN_ON is only for internal kernel errors (see comment in >>> include/asm-generic/bug.h). >> >> The documentation makes sense so in this case a pr_err like message will suffice. > > (could it be a kvm_debug() at most?) > > Do we need to print anything at all? User-space asked us for something we can't do. > Filling up the kernel log with user-space's mistakes makes it harder to debug the kernel > when something goes wrong. > > kvm_arm_pmu_v3_init() returns -ENODEV if you ask if for the PMU and the platform can't > support it. Isn't the returned error enough? Yes Agree that most of the time the user invoked functions are just returned with error value in case of failure. Thanks for the details. Regards, Amit D > > >> Btw >> there is one WARN in the function kvm_set_ipa_limit in the same file. > > That is called once via kvm_arch_init(), it can't be triggered repeatedly from user-space. > > > Thanks, > > James >
WARNING: multiple messages have this Message-ID (diff)
From: Amit Daniel Kachhap <amit.kachhap@arm.com> To: James Morse <james.morse@arm.com>, Kristina Martsenko <kristina.martsenko@arm.com> Cc: Mark Rutland <mark.rutland@arm.com>, Andrew Jones <drjones@redhat.com>, linux-kernel@vger.kernel.org, Julien Thierry <julien.thierry@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Christoffer Dall <christoffer.dall@arm.com>, kvmarm@lists.cs.columbia.edu, Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>, Dave Martin <Dave.Martin@arm.com>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v7 7/10] KVM: arm/arm64: context-switch ptrauth registers Date: Thu, 28 Mar 2019 16:59:17 +0530 [thread overview] Message-ID: <8c38a9fe-8310-4903-7042-e8b5eb3b5f1b@arm.com> (raw) In-Reply-To: <13ab02cf-db27-d604-6e5f-d276dec0779b@arm.com> Hi James, On 3/27/19 11:46 PM, James Morse wrote: > Hi Amit, Kristina, > > On 27/03/2019 03:21, Amit Daniel Kachhap wrote: >> On 3/26/19 11:31 PM, Kristina Martsenko wrote: >>> On 26/03/2019 04:03, Amit Daniel Kachhap wrote: >>>> On 3/26/19 1:34 AM, Kristina Martsenko wrote: >>>>> On 19/03/2019 08:30, Amit Daniel Kachhap wrote: >>>>>> From: Mark Rutland <mark.rutland@arm.com> >>>>>> >>>>>> When pointer authentication is supported, a guest may wish to use it. >>>>>> This patch adds the necessary KVM infrastructure for this to work, with >>>>>> a semi-lazy context switch of the pointer auth state. > >>>>>> + if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) || >>>>>> + test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features)) {>>>>> + /* Verify that KVM startup matches the conditions for ptrauth */ >>>>>> + if (WARN_ON(!vcpu_has_ptrauth(vcpu))) >>>>>> + return -EINVAL; >>>>>> + } > >>> One more thing - I think the WARN_ON() here should be removed. Otherwise >>> if panic_on_warn is set then userspace can panic the kernel. I think >>> WARN_ON is only for internal kernel errors (see comment in >>> include/asm-generic/bug.h). >> >> The documentation makes sense so in this case a pr_err like message will suffice. > > (could it be a kvm_debug() at most?) > > Do we need to print anything at all? User-space asked us for something we can't do. > Filling up the kernel log with user-space's mistakes makes it harder to debug the kernel > when something goes wrong. > > kvm_arm_pmu_v3_init() returns -ENODEV if you ask if for the PMU and the platform can't > support it. Isn't the returned error enough? Yes Agree that most of the time the user invoked functions are just returned with error value in case of failure. Thanks for the details. Regards, Amit D > > >> Btw >> there is one WARN in the function kvm_set_ipa_limit in the same file. > > That is called once via kvm_arch_init(), it can't be triggered repeatedly from user-space. > > > Thanks, > > James > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-28 11:29 UTC|newest] Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-19 8:30 [PATCH v7 0/10] Add ARMv8.3 pointer authentication for kvm guest Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 1/10] KVM: arm64: Propagate vcpu into read_id_reg() Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 2/10] KVM: arm64: Support runtime sysreg visibility filtering Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 3/10] KVM: arm64: Move hyp_symbol_addr to fix dependency Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-20 8:49 ` Julien Thierry 2019-03-20 8:49 ` Julien Thierry 2019-03-21 5:29 ` Amit Daniel Kachhap 2019-03-21 5:29 ` Amit Daniel Kachhap 2019-03-21 5:29 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 4/10] KVM: arm/arm64: preserve host HCR_EL2 value Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 5/10] KVM: arm/arm64: preserve host MDCR_EL2 value Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-25 20:04 ` Kristina Martsenko 2019-03-25 20:04 ` Kristina Martsenko 2019-03-26 3:55 ` Amit Daniel Kachhap 2019-03-26 3:55 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 6/10] KVM: arm64: Add vcpu feature flags to control ptrauth accessibility Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 7/10] KVM: arm/arm64: context-switch ptrauth registers Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-20 12:13 ` Julien Thierry 2019-03-20 12:13 ` Julien Thierry 2019-03-21 6:08 ` Amit Daniel Kachhap 2019-03-21 6:08 ` Amit Daniel Kachhap 2019-03-21 8:29 ` Julien Thierry 2019-03-21 8:29 ` Julien Thierry 2019-03-25 20:04 ` Kristina Martsenko 2019-03-25 20:04 ` Kristina Martsenko 2019-03-26 4:03 ` Amit Daniel Kachhap 2019-03-26 4:03 ` Amit Daniel Kachhap 2019-03-26 18:01 ` Kristina Martsenko 2019-03-26 18:01 ` Kristina Martsenko 2019-03-27 3:21 ` Amit Daniel Kachhap 2019-03-27 3:21 ` Amit Daniel Kachhap 2019-03-27 3:21 ` Amit Daniel Kachhap 2019-03-27 18:16 ` James Morse 2019-03-27 18:16 ` James Morse 2019-03-27 18:16 ` James Morse 2019-03-28 11:29 ` Amit Daniel Kachhap [this message] 2019-03-28 11:29 ` Amit Daniel Kachhap 2019-03-28 18:51 ` James Morse 2019-03-28 18:51 ` James Morse 2019-03-29 5:54 ` Amit Daniel Kachhap 2019-03-29 5:54 ` Amit Daniel Kachhap 2019-03-29 5:54 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 8/10] KVM: arm64: Add capability to advertise ptrauth for guest Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-25 20:05 ` Kristina Martsenko 2019-03-25 20:05 ` Kristina Martsenko 2019-03-26 4:12 ` Amit Daniel Kachhap 2019-03-26 4:12 ` Amit Daniel Kachhap 2019-03-26 4:12 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [PATCH v7 9/10] KVM: arm64: docs: document KVM support of pointer authentication Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap 2019-03-20 13:37 ` Julien Thierry 2019-03-20 13:37 ` Julien Thierry 2019-03-20 15:04 ` Kristina Martsenko 2019-03-20 15:04 ` Kristina Martsenko 2019-03-20 18:06 ` Julien Thierry 2019-03-20 18:06 ` Julien Thierry 2019-03-20 20:56 ` Kristina Martsenko 2019-03-20 20:56 ` Kristina Martsenko 2019-03-21 6:41 ` Amit Daniel Kachhap 2019-03-21 6:41 ` Amit Daniel Kachhap 2019-03-25 20:05 ` Kristina Martsenko 2019-03-25 20:05 ` Kristina Martsenko 2019-03-27 10:44 ` Dave Martin 2019-03-27 10:44 ` Dave Martin 2019-03-27 11:49 ` Amit Daniel Kachhap 2019-03-27 11:49 ` Amit Daniel Kachhap 2019-03-27 13:50 ` Dave Martin 2019-03-27 13:50 ` Dave Martin 2019-03-28 10:13 ` Amit Daniel Kachhap 2019-03-28 10:13 ` Amit Daniel Kachhap 2019-03-19 8:30 ` [kvmtool PATCH v7 10/10] KVM: arm/arm64: Add a vcpu feature for " Amit Daniel Kachhap 2019-03-19 8:30 ` Amit Daniel Kachhap
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