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Thu, 26 Aug 2021 09:43:53 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJBvJ-009hWy-09 for linux-arm-kernel@lists.infradead.org; Thu, 26 Aug 2021 09:43:50 +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 4E3B760F44; Thu, 26 Aug 2021 09:43:48 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) 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 1mJBvG-007JiY-92; Thu, 26 Aug 2021 10:43:46 +0100 Date: Thu, 26 Aug 2021 10:43:45 +0100 Message-ID: <874kbcpmlq.wl-maz@kernel.org> From: Marc Zyngier To: Andrew Jones Cc: Oliver Upton , kvmarm@lists.cs.columbia.edu, pshier@google.com, ricarkol@google.com, rananta@google.com, reijiw@google.com, jingzhangos@google.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, Alexandru.Elisei@arm.com, suzuki.poulose@arm.com, Peter Maydell Subject: Re: KVM/arm64: Guest ABI changes do not appear rollback-safe In-Reply-To: <20210826085429.b67fzkshhl3s2vfr@gator.home> References: <87mtp5q3gx.wl-maz@kernel.org> <87fsuxq049.wl-maz@kernel.org> <20210825150713.5rpwzm4grfn7akcw@gator.home> <20210826084945.yknl64gklxtygwal@gator.home> <20210826085429.b67fzkshhl3s2vfr@gator.home> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (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: 185.219.108.64 X-SA-Exim-Rcpt-To: drjones@redhat.com, oupton@google.com, kvmarm@lists.cs.columbia.edu, pshier@google.com, ricarkol@google.com, rananta@google.com, reijiw@google.com, jingzhangos@google.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, Alexandru.Elisei@arm.com, suzuki.poulose@arm.com, peter.maydell@linaro.org 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-20210826_024349_115367_E362EB21 X-CRM114-Status: GOOD ( 24.69 ) 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 On Thu, 26 Aug 2021 09:54:29 +0100, Andrew Jones wrote: [...] > I see Marc just replied stating we'll probably just have a single > register. The KVM_GET_SUPPORTED_CPUID type of ioctl would be > overkill in that case (get-one_reg is enough). Anyway it can > always be added later if we expand into more registers. Here's what I propose for the KVM-specific hypercalls. Compile tested only, plenty of nits to sort out. But you'll get the general idea. Something similar could be implemented for ARM-architected hypercalls such as TRNG. M. diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index f8be56d5342b..3fcca7cc9668 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -136,6 +136,9 @@ struct kvm_arch { /* Memory Tagging Extension enabled for the guest */ bool mte_enabled; + + /* Bitmap of enabled hypercalls */ + unsigned long hc_bmap; }; struct kvm_vcpu_fault_info { diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h index b3edde68bc3e..8d7a1a93f12c 100644 --- a/arch/arm64/include/uapi/asm/kvm.h +++ b/arch/arm64/include/uapi/asm/kvm.h @@ -281,6 +281,9 @@ struct kvm_arm_copy_mte_tags { #define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED 3 #define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED (1U << 4) +#define KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0 KVM_REG_ARM_FW_REG(3) +#define KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_1 KVM_REG_ARM_FW_REG(4) + /* SVE registers */ #define KVM_REG_ARM64_SVE (0x15 << KVM_REG_ARM_COPROC_SHIFT) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index fe102cd2e518..dbc136675b02 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -130,6 +130,13 @@ static void set_default_spectre(struct kvm *kvm) kvm->arch.pfr0_csv3 = 1; } + +static void set_default_vendor_hypercalls(struct kvm *kvm) +{ + kvm->arch.hc_bmap = (BIT(ARM_SMCCC_KVM_FUNC_FEATURES) | + BIT(ARM_SMCCC_KVM_FUNC_PTP)); +} + /** * kvm_arch_init_vm - initializes a VM data structure * @kvm: pointer to the KVM struct @@ -156,6 +163,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) kvm->arch.max_vcpus = kvm_arm_default_max_vcpus(); set_default_spectre(kvm); + set_default_vendor_hypercalls(kvm); return ret; out_free_stage2_pgd: diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c index 30da78f72b3b..11f79e790f7d 100644 --- a/arch/arm64/kvm/hypercalls.c +++ b/arch/arm64/kvm/hypercalls.c @@ -127,8 +127,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3; break; case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID: - val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES); - val[0] |= BIT(ARM_SMCCC_KVM_FUNC_PTP); + val[0] = vcpu->kvm->arch.hc_bmap; break; case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID: kvm_ptp_get_time(vcpu, val); diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c index 74c47d420253..ceef0c706d50 100644 --- a/arch/arm64/kvm/psci.c +++ b/arch/arm64/kvm/psci.c @@ -404,21 +404,26 @@ int kvm_psci_call(struct kvm_vcpu *vcpu) }; } +static const u64 fw_reg_ids[] = { + KVM_REG_ARM_PSCI_VERSION, + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, + KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0, +}; + int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu) { - return 3; /* PSCI version and two workaround registers */ + return ARRAY_SIZE(fw_reg_ids); } int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) { - if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices++)) - return -EFAULT; - - if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, uindices++)) - return -EFAULT; + int i; - if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, uindices++)) - return -EFAULT; + for (i = 0; i < ARRAY_SIZE(fw_reg_ids); i++) { + if (put_user(fw_reg_ids[i], uindices++)) + return -EFAULT; + } return 0; } @@ -477,6 +482,10 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2: val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK; break; + case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0: + val = vcpu->kvm->arch.hc_bmap; + break; + case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_1: default: return -ENOENT; } @@ -515,8 +524,9 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) return -EINVAL; vcpu->kvm->arch.psci_version = val; return 0; + default: + return -EINVAL; } - break; } case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1: @@ -563,9 +573,16 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) return -EINVAL; return 0; + case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_0: + /* FIXME: no vcpu should have run */ + /* Exclude any unknown bit */ + if (val & ~(BIT(ARM_SMCCC_KVM_FUNC_FEATURES) | + BIT(ARM_SMCCC_KVM_FUNC_PTP))) + return -EINVAL; + vcpu->kvm->arch.hc_bmap = val; + return 0; + case KVM_REG_ARM_KVM_SPECIFIC_HYPERCALLS_1: default: return -ENOENT; } - - return -EINVAL; } -- 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