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[24.155.109.49]) by smtp.googlemail.com with ESMTPSA id a16sm77241otk.39.2020.10.28.11.28.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Oct 2020 11:28:42 -0700 (PDT) From: Rob Herring To: Will Deacon , Catalin Marinas , Marc Zyngier Subject: [PATCH v7 2/2] arm64: Add workaround for Arm Cortex-A77 erratum 1508412 Date: Wed, 28 Oct 2020 13:28:39 -0500 Message-Id: <20201028182839.166037-2-robh@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201028182839.166037-1-robh@kernel.org> References: <20201028182839.166037-1-robh@kernel.org> MIME-Version: 1.0 Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Cortex-A77 r0p0 and r1p0, a sequence of a non-cacheable or device load and a store exclusive or PAR_EL1 read can cause a deadlock. The workaround requires a DMB SY before and after a PAR_EL1 register read. In addition, it's possible an interrupt (doing a device read) or KVM guest exit could be taken between the DMB and PAR read, so we also need a DMB before returning from interrupt and before returning to a guest. A deadlock is still possible with the workaround as KVM guests must also have the workaround. IOW, a malicious guest can deadlock an affected systems. This workaround also depends on a firmware counterpart to enable the h/w to insert DMB SY after load and store exclusive instructions. See the errata document SDEN-1152370 v10 [1] for more information. [1] https://static.docs.arm.com/101992/0010/Arm_Cortex_A77_MP074_Software_Developer_Errata_Notice_v10.pdf Cc: Catalin Marinas Cc: James Morse Cc: Suzuki K Poulose Cc: Will Deacon Cc: Julien Thierry Cc: kvmarm@lists.cs.columbia.edu Acked-by: Marc Zyngier Signed-off-by: Rob Herring --- v7: - Rebase on 5.10-rc1 v6: - Do dmb on kernel_exit rather than disabling interrupts around PAR read v5: - Rebase on v5.9-rc3 - Disable interrupts around PAR reads - Add DMB on return to guest v4: - Move read_sysreg_par out of KVM code to sysreg.h to share - Also use read_sysreg_par in fault.c and kvm/sys_regs.c - Use alternative f/w for dmbs around PAR read - Use cpus_have_final_cap instead of cpus_have_const_cap - Add note about speculation of PAR read v3: - Add dmbs around PAR reads in KVM code - Clean-up 'work-around' and 'errata' v2: - Don't disable KVM, just print warning --- Documentation/arm64/silicon-errata.rst | 2 ++ arch/arm64/Kconfig | 20 ++++++++++++++++++++ arch/arm64/include/asm/cpucaps.h | 3 ++- arch/arm64/include/asm/sysreg.h | 9 +++++++++ arch/arm64/kernel/cpu_errata.c | 10 ++++++++++ arch/arm64/kernel/entry.S | 3 +++ arch/arm64/kvm/arm.c | 3 ++- arch/arm64/kvm/hyp/include/hyp/switch.h | 21 +++++++++++++-------- arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 2 +- arch/arm64/kvm/hyp/nvhe/switch.c | 2 +- arch/arm64/kvm/hyp/vhe/switch.c | 2 +- arch/arm64/kvm/sys_regs.c | 2 +- arch/arm64/mm/fault.c | 2 +- 13 files changed, 66 insertions(+), 15 deletions(-) diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index d3587805de64..719510247292 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -90,6 +90,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A76 | #1463225 | ARM64_ERRATUM_1463225 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A77 | #1508412 | ARM64_ERRATUM_1508412 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f858c352f72a..1d466addb078 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -636,6 +636,26 @@ config ARM64_ERRATUM_1542419 If unsure, say Y. +config ARM64_ERRATUM_1508412 + bool "Cortex-A77: 1508412: workaround deadlock on sequence of NC/Device load and store exclusive or PAR read" + default y + help + This option adds a workaround for Arm Cortex-A77 erratum 1508412. + + Affected Cortex-A77 cores (r0p0, r1p0) could deadlock on a sequence + of a store-exclusive or read of PAR_EL1 and a load with device or + non-cacheable memory attributes. The workaround depends on a firmware + counterpart. + + KVM guests must also have the workaround implemented or they can + deadlock the system. + + Work around the issue by inserting DMB SY barriers around PAR_EL1 + register reads and warning KVM users. The DMB barrier is sufficient + to prevent a speculative PAR_EL1 read. + + If unsure, say Y. + config CAVIUM_ERRATUM_22375 bool "Cavium erratum 22375, 24313" default y diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index 42868dbd29fd..e7d98997c09c 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -65,7 +65,8 @@ #define ARM64_HAS_ARMv8_4_TTL 55 #define ARM64_HAS_TLB_RANGE 56 #define ARM64_MTE 57 +#define ARM64_WORKAROUND_1508412 58 -#define ARM64_NCAPS 58 +#define ARM64_NCAPS 59 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index d52c1b3ce589..174817ba119c 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -1007,6 +1007,7 @@ #include #include +#include #define __DEFINE_MRS_MSR_S_REGNUM \ " .irp num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n" \ @@ -1095,6 +1096,14 @@ write_sysreg_s(__scs_new, sysreg); \ } while (0) +#define read_sysreg_par() ({ \ + u64 par; \ + asm(ALTERNATIVE("nop", "dmb sy", ARM64_WORKAROUND_1508412)); \ + par = read_sysreg(par_el1); \ + asm(ALTERNATIVE("nop", "dmb sy", ARM64_WORKAROUND_1508412)); \ + par; \ +}) + #endif #endif /* __ASM_SYSREG_H */ diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 24d75af344b1..61314fd70f13 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -522,6 +522,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .matches = has_neoverse_n1_erratum_1542419, .cpu_enable = cpu_enable_trap_ctr_access, }, +#endif +#ifdef CONFIG_ARM64_ERRATUM_1508412 + { + /* we depend on the firmware portion for correctness */ + .desc = "ARM erratum 1508412 (kernel portion)", + .capability = ARM64_WORKAROUND_1508412, + ERRATA_MIDR_RANGE(MIDR_CORTEX_A77, + 0, 0, + 1, 0), + }, #endif { } diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index f30007dff35f..b295fb912b12 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -365,6 +365,9 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 br x30 #endif .else + /* Ensure any device/NC reads complete */ + alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 + eret .endif sb diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index f56122eedffc..8f8fca47abfc 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -1719,7 +1719,8 @@ int kvm_arch_init(void *opaque) return -ENODEV; } - if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE)) + if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE) || + cpus_have_final_cap(ARM64_WORKAROUND_1508412)) kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \ "Only trusted guests should be used on this system.\n"); diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index 313a8fa3c721..1f875a8f20c4 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -140,9 +140,9 @@ static inline bool __translate_far_to_hpfar(u64 far, u64 *hpfar) * We do need to save/restore PAR_EL1 though, as we haven't * saved the guest context yet, and we may return early... */ - par = read_sysreg(par_el1); + par = read_sysreg_par(); if (!__kvm_at("s1e1r", far)) - tmp = read_sysreg(par_el1); + tmp = read_sysreg_par(); else tmp = SYS_PAR_EL1_F; /* back to the guest */ write_sysreg(par, par_el1); @@ -421,7 +421,7 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) && kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 && handle_tx2_tvm(vcpu)) - return true; + goto guest; /* * We trap the first access to the FP/SIMD to save the host context @@ -431,13 +431,13 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) * Similarly for trapped SVE accesses. */ if (__hyp_handle_fpsimd(vcpu)) - return true; + goto guest; if (__hyp_handle_ptrauth(vcpu)) - return true; + goto guest; if (!__populate_fault_info(vcpu)) - return true; + goto guest; if (static_branch_unlikely(&vgic_v2_cpuif_trap)) { bool valid; @@ -452,7 +452,7 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) int ret = __vgic_v2_perform_cpuif_access(vcpu); if (ret == 1) - return true; + goto guest; /* Promote an illegal access to an SError.*/ if (ret == -1) @@ -468,12 +468,17 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) int ret = __vgic_v3_perform_cpuif_access(vcpu); if (ret == 1) - return true; + goto guest; } exit: /* Return to the host kernel and handle the exit */ return false; + +guest: + /* Re-enter the guest */ + asm(ALTERNATIVE("nop", "dmb sy", ARM64_WORKAROUND_1508412)); + return true; } static inline void __kvm_unexpected_el2_exception(void) diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h index 7a986030145f..cce43bfe158f 100644 --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h @@ -43,7 +43,7 @@ static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt) ctxt_sys_reg(ctxt, CONTEXTIDR_EL1) = read_sysreg_el1(SYS_CONTEXTIDR); ctxt_sys_reg(ctxt, AMAIR_EL1) = read_sysreg_el1(SYS_AMAIR); ctxt_sys_reg(ctxt, CNTKCTL_EL1) = read_sysreg_el1(SYS_CNTKCTL); - ctxt_sys_reg(ctxt, PAR_EL1) = read_sysreg(par_el1); + ctxt_sys_reg(ctxt, PAR_EL1) = read_sysreg_par(); ctxt_sys_reg(ctxt, TPIDR_EL1) = read_sysreg(tpidr_el1); ctxt_sys_reg(ctxt, SP_EL1) = read_sysreg(sp_el1); diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index a457a0306e03..8ae8160bc93a 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -250,7 +250,7 @@ void __noreturn hyp_panic(void) { u64 spsr = read_sysreg_el2(SYS_SPSR); u64 elr = read_sysreg_el2(SYS_ELR); - u64 par = read_sysreg(par_el1); + u64 par = read_sysreg_par(); bool restore_host = true; struct kvm_cpu_context *host_ctxt; struct kvm_vcpu *vcpu; diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index fe69de16dadc..62546e20b251 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -215,7 +215,7 @@ void __noreturn hyp_panic(void) { u64 spsr = read_sysreg_el2(SYS_SPSR); u64 elr = read_sysreg_el2(SYS_ELR); - u64 par = read_sysreg(par_el1); + u64 par = read_sysreg_par(); __hyp_call_panic(spsr, elr, par); unreachable(); diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index d9117bc56237..41348a7781d9 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -95,7 +95,7 @@ static bool __vcpu_read_sys_reg_from_cpu(int reg, u64 *val) case AMAIR_EL1: *val = read_sysreg_s(SYS_AMAIR_EL12); break; case CNTKCTL_EL1: *val = read_sysreg_s(SYS_CNTKCTL_EL12); break; case ELR_EL1: *val = read_sysreg_s(SYS_ELR_EL12); break; - case PAR_EL1: *val = read_sysreg_s(SYS_PAR_EL1); break; + case PAR_EL1: *val = read_sysreg_par(); break; case DACR32_EL2: *val = read_sysreg_s(SYS_DACR32_EL2); break; case IFSR32_EL2: *val = read_sysreg_s(SYS_IFSR32_EL2); break; case DBGVCR32_EL2: *val = read_sysreg_s(SYS_DBGVCR32_EL2); break; diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 94c99c1c19e3..1ee94002801f 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -262,7 +262,7 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr, local_irq_save(flags); asm volatile("at s1e1r, %0" :: "r" (addr)); isb(); - par = read_sysreg(par_el1); + par = read_sysreg_par(); local_irq_restore(flags); /* -- 2.25.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm