Cortex-A510's erratum #2077057 causes SPSR_EL2 to be corrupted when single-stepping authenticated ERET instructions. A single step is expected, but a pointer authentication trap is taken instead. The erratum causes SPSR_EL1 to be copied to SPSR_EL2, which could allow EL1 to cause a return to EL2 with a guest controlled ELR_EL2. Because the conditions require an ERET into active-not-pending state, this is only a problem for the EL2 when EL2 is stepping EL1. In this case the previous SPSR_EL2 value is preserved in struct kvm_vcpu, and can be restored. Cc: stable@xxxxxxxxxxxxxxx # 53960faf2b73: arm64: Add Cortex-A510 CPU part definition Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: James Morse <james.morse@xxxxxxx> [maz: fixup cpucaps ordering] Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220127122052.1584324-5-james.morse@xxxxxxx diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 0ec7b7f1524b..ea281dd75517 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -100,6 +100,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A510 | #2051678 | ARM64_ERRATUM_2051678 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A510 | #2077057 | ARM64_ERRATUM_2077057 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A710 | #2119858 | ARM64_ERRATUM_2119858 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A710 | #2054223 | ARM64_ERRATUM_2054223 | diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f2b5a4abef21..cbcd42decb2a 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -680,6 +680,22 @@ config ARM64_ERRATUM_2051678 If unsure, say Y. +config ARM64_ERRATUM_2077057 + bool "Cortex-A510: 2077057: workaround software-step corrupting SPSR_EL2" + help + This option adds the workaround for ARM Cortex-A510 erratum 2077057. + Affected Cortex-A510 may corrupt SPSR_EL2 when the a step exception is + expected, but a Pointer Authentication trap is taken instead. The + erratum causes SPSR_EL1 to be copied to SPSR_EL2, which could allow + EL1 to cause a return to EL2 with a guest controlled ELR_EL2. + + This can only happen when EL2 is stepping EL1. + + When these conditions occur, the SPSR_EL2 value is unchanged from the + previous guest entry, and can be restored from the in-memory copy. + + If unsure, say Y. + config ARM64_ERRATUM_2119858 bool "Cortex-A710/X2: 2119858: workaround TRBE overwriting trace data in FILL mode" default y diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 066098198c24..b217941713a8 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -600,6 +600,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = { CAP_MIDR_RANGE_LIST(trbe_write_out_of_range_cpus), }, #endif +#ifdef CONFIG_ARM64_ERRATUM_2077057 + { + .desc = "ARM erratum 2077057", + .capability = ARM64_WORKAROUND_2077057, + .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, + ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 2), + }, +#endif #ifdef CONFIG_ARM64_ERRATUM_2064142 { .desc = "ARM erratum 2064142", diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index 331dd10821df..701cfb964905 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -402,6 +402,24 @@ static inline bool kvm_hyp_handle_exit(struct kvm_vcpu *vcpu, u64 *exit_code) return false; } +static inline void synchronize_vcpu_pstate(struct kvm_vcpu *vcpu, u64 *exit_code) +{ + /* + * Check for the conditions of Cortex-A510's #2077057. When these occur + * SPSR_EL2 can't be trusted, but isn't needed either as it is + * unchanged from the value in vcpu_gp_regs(vcpu)->pstate. + * Are we single-stepping the guest, and took a PAC exception from the + * active-not-pending state? + */ + if (cpus_have_final_cap(ARM64_WORKAROUND_2077057) && + vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP && + *vcpu_cpsr(vcpu) & DBG_SPSR_SS && + ESR_ELx_EC(read_sysreg_el2(SYS_ESR)) == ESR_ELx_EC_PAC) + write_sysreg_el2(*vcpu_cpsr(vcpu), SYS_SPSR); + + vcpu->arch.ctxt.regs.pstate = read_sysreg_el2(SYS_SPSR); +} + /* * Return true when we were able to fixup the guest exit and should return to * the guest, false when we should restore the host state and return to the @@ -413,7 +431,7 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) * Save PSTATE early so that we can evaluate the vcpu mode * early on. */ - vcpu->arch.ctxt.regs.pstate = read_sysreg_el2(SYS_SPSR); + synchronize_vcpu_pstate(vcpu, exit_code); /* * Check whether we want to repaint the state one way or diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index e7719e8f18de..9c65b1e25a96 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -55,9 +55,10 @@ WORKAROUND_1418040 WORKAROUND_1463225 WORKAROUND_1508412 WORKAROUND_1542419 -WORKAROUND_2064142 -WORKAROUND_2038923 WORKAROUND_1902691 +WORKAROUND_2038923 +WORKAROUND_2064142 +WORKAROUND_2077057 WORKAROUND_TRBE_OVERWRITE_FILL_MODE WORKAROUND_TSB_FLUSH_FAILURE WORKAROUND_TRBE_WRITE_OUT_OF_RANGE
