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[209.132.180.67]) by mx.google.com with ESMTP id 92si7819533plw.158.2019.03.01.01.43.48; Fri, 01 Mar 2019 01:44:03 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387683AbfCAJl1 (ORCPT + 99 others); Fri, 1 Mar 2019 04:41:27 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:60450 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733133AbfCAJl0 (ORCPT ); Fri, 1 Mar 2019 04:41:26 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C79FD1688; Fri, 1 Mar 2019 01:41:25 -0800 (PST) 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 2709F3F575; Fri, 1 Mar 2019 01:41:22 -0800 (PST) Subject: Re: [PATCH v6 4/6] arm64/kvm: add a userspace option to enable pointer authentication To: Dave Martin Cc: linux-arm-kernel@lists.infradead.org, Marc Zyngier , Catalin Marinas , Will Deacon , Kristina Martsenko , kvmarm@lists.cs.columbia.edu, Ramana Radhakrishnan , linux-kernel@vger.kernel.org References: <1550568271-5319-1-git-send-email-amit.kachhap@arm.com> <1550568271-5319-5-git-send-email-amit.kachhap@arm.com> <20190221155350.GY3567@e103592.cambridge.arm.com> From: Amit Daniel Kachhap Message-ID: <56edb86f-7205-4714-823a-d26005d175ab@arm.com> Date: Fri, 1 Mar 2019 15:11:20 +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: <20190221155350.GY3567@e103592.cambridge.arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2/21/19 9:23 PM, Dave Martin wrote: > On Tue, Feb 19, 2019 at 02:54:29PM +0530, Amit Daniel Kachhap wrote: >> This feature will allow the KVM guest to allow the handling of >> pointer authentication instructions or to treat them as undefined >> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to >> supply this parameter instead of creating a new API. >> >> A new register is not created to pass this parameter via >> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH) >> supplied is enough to enable this feature. >> >> Signed-off-by: Amit Daniel Kachhap >> Cc: Mark Rutland >> Cc: Marc Zyngier >> Cc: Christoffer Dall >> Cc: kvmarm@lists.cs.columbia.edu >> --- >> Documentation/arm64/pointer-authentication.txt | 9 +++++---- >> Documentation/virtual/kvm/api.txt | 4 ++++ >> arch/arm64/include/asm/kvm_host.h | 3 ++- >> arch/arm64/include/uapi/asm/kvm.h | 1 + >> arch/arm64/kvm/handle_exit.c | 2 +- >> arch/arm64/kvm/hyp/ptrauth-sr.c | 16 +++++++++++++++- >> arch/arm64/kvm/reset.c | 3 +++ >> arch/arm64/kvm/sys_regs.c | 26 +++++++++++++------------- >> include/uapi/linux/kvm.h | 1 + >> 9 files changed, 45 insertions(+), 20 deletions(-) >> > > [...] > >> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h >> index 1bacf78..2768a53 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -43,7 +43,7 @@ >> >> #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS >> >> -#define KVM_VCPU_MAX_FEATURES 4 >> +#define KVM_VCPU_MAX_FEATURES 5 >> >> #define KVM_REQ_SLEEP \ >> KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) >> @@ -451,6 +451,7 @@ static inline bool kvm_arch_requires_vhe(void) >> return false; >> } >> >> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu); >> static inline bool kvm_supports_ptrauth(void) >> { >> return has_vhe() && system_supports_address_auth() && > > [...] > >> diff --git a/arch/arm64/kvm/hyp/ptrauth-sr.c b/arch/arm64/kvm/hyp/ptrauth-sr.c >> index 528ee6e..6846a23 100644 >> --- a/arch/arm64/kvm/hyp/ptrauth-sr.c >> +++ b/arch/arm64/kvm/hyp/ptrauth-sr.c >> @@ -93,9 +93,23 @@ void kvm_arm_vcpu_ptrauth_reset(struct kvm_vcpu *vcpu) > > [...] > >> +/** >> + * kvm_arm_vcpu_ptrauth_allowed - checks if ptrauth feature is allowed by user >> + * >> + * @vcpu: The VCPU pointer >> + * >> + * This function will be used to check userspace option to have ptrauth or not >> + * in the guest kernel. >> + */ >> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu) >> +{ >> + return kvm_supports_ptrauth() && >> + test_bit(KVM_ARM_VCPU_PTRAUTH, vcpu->arch.features); >> +} > > Nit: for SVE is called the equivalent helper vcpu_has_sve(vcpu). > > Neither naming is more correct, but it would make sense to be > consistent. We will likely accumulate more of these vcpu feature > predicates over time. > > Given that this is trivial and will be used all over the place, it > probably makes sense to define it in kvm_host.h rather than having it > out of line in a separate C file. Ok I checked the SVE implementation. vcpu_has_ptrauth macro make more sense. > >> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c >> index b72a3dd..987e0c3c 100644 >> --- a/arch/arm64/kvm/reset.c >> +++ b/arch/arm64/kvm/reset.c >> @@ -91,6 +91,9 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext) >> case KVM_CAP_ARM_VM_IPA_SIZE: >> r = kvm_ipa_limit; >> break; >> + case KVM_CAP_ARM_PTRAUTH: >> + r = kvm_supports_ptrauth(); >> + break; >> default: >> r = 0; >> } >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c >> index 12529df..f7bcc60 100644 >> --- a/arch/arm64/kvm/sys_regs.c >> +++ b/arch/arm64/kvm/sys_regs.c >> @@ -1055,7 +1055,7 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu, >> } >> >> /* Read a sanitised cpufeature ID register by sys_reg_desc */ >> -static u64 read_id_reg(struct sys_reg_desc const *r, bool raz) >> +static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz) >> { >> u32 id = sys_reg((u32)r->Op0, (u32)r->Op1, >> (u32)r->CRn, (u32)r->CRm, (u32)r->Op2); >> @@ -1071,7 +1071,7 @@ static u64 read_id_reg(struct sys_reg_desc const *r, bool raz) >> (0xfUL << ID_AA64ISAR1_API_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPI_SHIFT); >> - if (!kvm_supports_ptrauth()) { >> + if (!kvm_arm_vcpu_ptrauth_allowed(vcpu)) { >> kvm_debug("ptrauth unsupported for guests, suppressing\n"); >> val &= ~ptrauth_mask; >> } >> @@ -1095,7 +1095,7 @@ static bool __access_id_reg(struct kvm_vcpu *vcpu, >> if (p->is_write) >> return write_to_read_only(vcpu, p, r); >> >> - p->regval = read_id_reg(r, raz); >> + p->regval = read_id_reg(vcpu, r, raz); >> return true; >> } > > The SVE KVM series makes various overlapping changes to propagate vcpuo > into the relevant places, but hopefully the rebase is not too painful. > Many of the changes are probably virtually identical between the two > series. > > See for example [1]. Maybe you could cherry-pick and drop the > equivalent changes here (though if your series is picked up first, I > will live with it ;) Yes no issue. I will cherry-pick your specific patch and rebase mine on it. Thanks, Amit D > > [...] > > Cheers > ---Dave > > > [1] [PATCH v5 10/26] KVM: arm64: Propagate vcpu into read_id_reg() > https://lists.cs.columbia.edu/pipermail/kvmarm/2019-February/034687.html >