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    SubjectRe: [PATCH v2 16/16] arm64: Add ARM_SMCCC_ARCH_WORKAROUND_1 BP hardening support
    On 29 January 2018 at 17:45, Marc Zyngier <marc.zyngier@arm.com> wrote:
    > Add the detection and runtime code for ARM_SMCCC_ARCH_WORKAROUND_1.
    > It is lovely. Really.
    >
    > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
    > ---
    > arch/arm64/include/asm/kvm_psci.h | 63 ++++++++++++++++++++++++++++++++++++
    > arch/arm64/kernel/bpi.S | 20 ++++++++++++
    > arch/arm64/kernel/cpu_errata.c | 68 ++++++++++++++++++++++++++++++++++++++-
    > 3 files changed, 150 insertions(+), 1 deletion(-)
    > create mode 100644 arch/arm64/include/asm/kvm_psci.h
    >
    > diff --git a/arch/arm64/include/asm/kvm_psci.h b/arch/arm64/include/asm/kvm_psci.h

    Did you mean to add this file? It is mostly identical to include/kvm/arm_psci.h

    > new file mode 100644
    > index 000000000000..f553e3795a4e
    > --- /dev/null
    > +++ b/arch/arm64/include/asm/kvm_psci.h
    > @@ -0,0 +1,63 @@
    > +/*
    > + * Copyright (C) 2012,2013 - ARM Ltd
    > + * Author: Marc Zyngier <marc.zyngier@arm.com>
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License version 2 as
    > + * published by the Free Software Foundation.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + * You should have received a copy of the GNU General Public License
    > + * along with this program. If not, see <http://www.gnu.org/licenses/>.
    > + */
    > +
    > +#ifndef __ARM64_KVM_PSCI_H__
    > +#define __ARM64_KVM_PSCI_H__
    > +
    > +#include <linux/kvm_host.h>
    > +
    > +#define PSCI_VERSION(x,y) ((((x) & 0x7fff) << 16) | ((y) & 0xffff))
    > +#define KVM_ARM_PSCI_0_1 PSCI_VERSION(0, 1)
    > +#define KVM_ARM_PSCI_0_2 PSCI_VERSION(0, 2)
    > +#define KVM_ARM_PSCI_1_0 PSCI_VERSION(1, 0)
    > +
    > +#define KVM_ARM_PSCI_LATEST KVM_ARM_PSCI_1_0
    > +
    > +/*
    > + * We need the KVM pointer independently from the vcpu as we can call
    > + * this from HYP, and need to apply kern_hyp_va on it...
    > + */
    > +static inline int kvm_psci_version(struct kvm_vcpu *vcpu, struct kvm *kvm)
    > +{
    > + /*
    > + * Our PSCI implementation stays the same across versions from
    > + * v0.2 onward, only adding the few mandatory functions (such
    > + * as FEATURES with 1.0) that are required by newer
    > + * revisions. It is thus safe to return the latest, unless
    > + * userspace has instructed us otherwise.
    > + */
    > + if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features)) {
    > + if (kvm->arch.psci_version)
    > + return kvm->arch.psci_version;
    > +
    > + return KVM_ARM_PSCI_LATEST;
    > + }
    > +
    > + return KVM_ARM_PSCI_0_1;
    > +}
    > +
    > +
    > +int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
    > +
    > +struct kvm_one_reg;
    > +
    > +int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
    > +int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
    > +int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
    > +int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
    > +
    > +#endif /* __ARM64_KVM_PSCI_H__ */
    > diff --git a/arch/arm64/kernel/bpi.S b/arch/arm64/kernel/bpi.S
    > index 76225c2611ea..fdeed629f2c6 100644
    > --- a/arch/arm64/kernel/bpi.S
    > +++ b/arch/arm64/kernel/bpi.S
    > @@ -17,6 +17,7 @@
    > */
    >
    > #include <linux/linkage.h>
    > +#include <linux/arm-smccc.h>
    >
    > .macro ventry target
    > .rept 31
    > @@ -85,3 +86,22 @@ ENTRY(__qcom_hyp_sanitize_link_stack_start)
    > .endr
    > ldp x29, x30, [sp], #16
    > ENTRY(__qcom_hyp_sanitize_link_stack_end)
    > +
    > +.macro smccc_workaround_1 inst
    > + sub sp, sp, #(8 * 4)
    > + stp x2, x3, [sp, #(8 * 0)]
    > + stp x0, x1, [sp, #(8 * 2)]
    > + mov w0, #ARM_SMCCC_ARCH_WORKAROUND_1
    > + \inst #0
    > + ldp x2, x3, [sp, #(8 * 0)]
    > + ldp x0, x1, [sp, #(8 * 2)]
    > + add sp, sp, #(8 * 4)
    > +.endm
    > +
    > +ENTRY(__smccc_workaround_1_smc_start)
    > + smccc_workaround_1 smc
    > +ENTRY(__smccc_workaround_1_smc_end)
    > +
    > +ENTRY(__smccc_workaround_1_hvc_start)
    > + smccc_workaround_1 hvc
    > +ENTRY(__smccc_workaround_1_hvc_end)
    > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
    > index ed6881882231..36cff870d5d7 100644
    > --- a/arch/arm64/kernel/cpu_errata.c
    > +++ b/arch/arm64/kernel/cpu_errata.c
    > @@ -70,6 +70,10 @@ DEFINE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
    > extern char __psci_hyp_bp_inval_start[], __psci_hyp_bp_inval_end[];
    > extern char __qcom_hyp_sanitize_link_stack_start[];
    > extern char __qcom_hyp_sanitize_link_stack_end[];
    > +extern char __smccc_workaround_1_smc_start[];
    > +extern char __smccc_workaround_1_smc_end[];
    > +extern char __smccc_workaround_1_hvc_start[];
    > +extern char __smccc_workaround_1_hvc_end[];
    >
    > static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start,
    > const char *hyp_vecs_end)
    > @@ -116,6 +120,10 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
    > #define __psci_hyp_bp_inval_end NULL
    > #define __qcom_hyp_sanitize_link_stack_start NULL
    > #define __qcom_hyp_sanitize_link_stack_end NULL
    > +#define __smccc_workaround_1_smc_start NULL
    > +#define __smccc_workaround_1_smc_end NULL
    > +#define __smccc_workaround_1_hvc_start NULL
    > +#define __smccc_workaround_1_hvc_end NULL
    >
    > static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
    > const char *hyp_vecs_start,
    > @@ -142,17 +150,75 @@ static void install_bp_hardening_cb(const struct arm64_cpu_capabilities *entry,
    > __install_bp_hardening_cb(fn, hyp_vecs_start, hyp_vecs_end);
    > }
    >
    > +#include <uapi/linux/psci.h>
    > +#include <linux/arm-smccc.h>
    > #include <linux/psci.h>
    >
    > +static void call_smc_arch_workaround_1(void)
    > +{
    > + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
    > +}
    > +
    > +static void call_hvc_arch_workaround_1(void)
    > +{
    > + arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
    > +}
    > +
    > +static bool check_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry)
    > +{
    > + bp_hardening_cb_t cb;
    > + void *smccc_start, *smccc_end;
    > + struct arm_smccc_res res;
    > +
    > + if (!entry->matches(entry, SCOPE_LOCAL_CPU))
    > + return false;
    > +
    > + if (psci_ops.variant == SMCCC_VARIANT_1_0)
    > + return false;
    > +
    > + switch (psci_ops.conduit) {
    > + case PSCI_CONDUIT_HVC:
    > + arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
    > + ARM_SMCCC_ARCH_WORKAROUND_1, &res);
    > + if (res.a0)
    > + return false;
    > + cb = call_hvc_arch_workaround_1;
    > + smccc_start = __smccc_workaround_1_hvc_start;
    > + smccc_end = __smccc_workaround_1_hvc_end;
    > + break;
    > +
    > + case PSCI_CONDUIT_SMC:
    > + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
    > + ARM_SMCCC_ARCH_WORKAROUND_1, &res);
    > + if (res.a0)
    > + return false;
    > + cb = call_smc_arch_workaround_1;
    > + smccc_start = __smccc_workaround_1_smc_start;
    > + smccc_end = __smccc_workaround_1_smc_end;
    > + break;
    > +
    > + default:
    > + return false;
    > + }
    > +
    > + install_bp_hardening_cb(entry, cb, smccc_start, smccc_end);
    > +
    > + return true;
    > +}
    > +
    > static int enable_psci_bp_hardening(void *data)
    > {
    > const struct arm64_cpu_capabilities *entry = data;
    >
    > - if (psci_ops.get_version)
    > + if (psci_ops.get_version) {
    > + if (check_smccc_arch_workaround_1(entry))
    > + return 0;
    > +
    > install_bp_hardening_cb(entry,
    > (bp_hardening_cb_t)psci_ops.get_version,
    > __psci_hyp_bp_inval_start,
    > __psci_hyp_bp_inval_end);
    > + }
    >
    > return 0;
    > }
    > --
    > 2.14.2
    >

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