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 and the disabling of KVM. KVM must be disabled to prevent the problematic sequence in guests' EL1. 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. All the other PAR_EL1 reads besides the one in is_spurious_el1_translation_fault() are in KVM code, so the work-around is not needed for them. [1] https://static.docs.arm.com/101992/0010/Arm_Cortex_A77_MP074_Software_Developer_Errata_Notice_v10.pdf Cc: Catalin Marinas <catalin.mari...@arm.com> Cc: James Morse <james.mo...@arm.com> Cc: Suzuki K Poulose <suzuki.poul...@arm.com> Cc: Will Deacon <w...@kernel.org> Cc: Marc Zyngier <m...@kernel.org> Cc: Julien Thierry <julien.thierry.k...@gmail.com> Cc: kvmarm@lists.cs.columbia.edu Signed-off-by: Rob Herring <r...@kernel.org> --- v2: - Don't disable KVM, just print warning --- Documentation/arm64/silicon-errata.rst | 2 ++ arch/arm64/Kconfig | 19 +++++++++++++++++++ arch/arm64/include/asm/cpucaps.h | 3 ++- arch/arm64/kernel/cpu_errata.c | 10 ++++++++++ arch/arm64/kvm/arm.c | 3 ++- arch/arm64/mm/fault.c | 10 ++++++++++ 6 files changed, 45 insertions(+), 2 deletions(-) diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 936cf2a59ca4..716b279e3b33 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 a4a094bedcb2..28993ad4c649 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -626,6 +626,25 @@ 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 work-around implemented or they can + deadlock the system. + + Workaround the issue by inserting DMB SY barriers around PAR_EL1 + register reads and warning KVM users. + + 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 d7b3bb0cb180..2a2cdb4ced8b 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -62,7 +62,8 @@ #define ARM64_HAS_GENERIC_AUTH 52 #define ARM64_HAS_32BIT_EL1 53 #define ARM64_BTI 54 +#define ARM64_WORKAROUND_1508412 55 -#define ARM64_NCAPS 55 +#define ARM64_NCAPS 56 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index ad06d6802d2e..5eee8a75540c 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -938,6 +938,16 @@ 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/kvm/arm.c b/arch/arm64/kvm/arm.c index e2f50fa4d825..9f50e01eea00 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -1653,7 +1653,8 @@ int kvm_arch_init(void *opaque) return -ENODEV; } - if (cpus_have_const_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE)) + if (cpus_have_const_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE) || + cpus_have_const_cap(ARM64_WORKAROUND_1508412)) kvm_info("Guests without required CPU erratum work-arounds can deadlock system!\n" \ "Only trusted guests should be used on this system.\n"); diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 8afb238ff335..d599d60f06fd 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -260,7 +260,17 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr, local_irq_save(flags); asm volatile("at s1e1r, %0" :: "r" (addr)); isb(); + /* + * Arm Errata 1508412 requires dmb(sy) before and after reads of + * PAR_EL1. + * As this location is not a hot path, just condition it on the config + * option. + */ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1508412)) + dmb(sy); par = read_sysreg(par_el1); + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1508412)) + dmb(sy); local_irq_restore(flags); /* -- 2.25.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
