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On affected machines, always do writes to HCR_EL2 with async exceptions blocked. Signed-off-by: D Scott Phillips --- arch/arm64/Kconfig | 17 +++++++++++++++++ arch/arm64/include/asm/sysreg.h | 18 ++++++++++++++++-- arch/arm64/kernel/cpu_errata.c | 14 ++++++++++++++ arch/arm64/tools/cpucaps | 1 + 4 files changed, 48 insertions(+), 2 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index a182295e6f08b..e5fd87446a3b8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -445,6 +445,23 @@ menu "Kernel Features" menu "ARM errata workarounds via the alternatives framework" +config AMPERE_ERRATUM_AC03_CPU_36 + bool "AmpereOne: AC03_CPU_36: CPU can take an invalid exception, if an asynchronous exception to EL2 occurs while EL2 software is changing the EL2 exception controls." + default y + help + This option adds an alternative code sequence to work around Ampere + errata AC03_CPU_36 on AmpereOne. + + If an async exception happens at the same time as an update to the + controls for the target EL for async exceptions, an exception can be + delivered to the wrong EL. For example, an EL may be routed from EL2 + to EL1. + + The workaround masks all asynchronous exception types when writing + to HCR_EL2. + + If unsure, say Y. + config AMPERE_ERRATUM_AC03_CPU_38 bool "AmpereOne: AC03_CPU_38: Certain bits in the Virtualization Translation Control Register and Translation Control Registers do not follow RES0 semantics" default y diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 2639d3633073d..e7781f7e7f7a7 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -1136,14 +1136,28 @@ __val; \ }) +#define __sysreg_is_hcr_el2(r) \ + (__builtin_strcmp("hcr_el2", __stringify(r)) == 0) +#define __hcr_el2_ac03_cpu_36(r) \ + (IS_ENABLED(CONFIG_AMPERE_ERRATUM_AC03_CPU_36) && \ + __sysreg_is_hcr_el2(r) && \ + alternative_has_cap_unlikely(ARM64_WORKAROUND_AMPERE_AC03_CPU_36)) + /* * The "Z" constraint normally means a zero immediate, but when combined with * the "%x0" template means XZR. */ #define write_sysreg(v, r) do { \ u64 __val = (u64)(v); \ - asm volatile("msr " __stringify(r) ", %x0" \ - : : "rZ" (__val)); \ + if (__hcr_el2_ac03_cpu_36(r)) { \ + u64 __daif; \ + asm volatile("mrs %0, daif; msr daifset, #0xf;" \ + "msr hcr_el2, %x1; msr daif, %0" \ + : "=&r"(__daif) : "rZ" (__val)); \ + } else { \ + asm volatile("msr " __stringify(r) ", %x0" \ + : : "rZ" (__val)); \ + } \ } while (0) /* diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index b55f5f7057502..89be85bf631fd 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -549,6 +549,13 @@ static const struct midr_range erratum_spec_ssbs_list[] = { }; #endif +#ifdef CONFIG_AMPERE_ERRATUM_AC03_CPU_36 +static const struct midr_range erratum_ac03_cpu_36_list[] = { + MIDR_ALL_VERSIONS(MIDR_AMPERE1), + {}, +}; +#endif + #ifdef CONFIG_AMPERE_ERRATUM_AC03_CPU_38 static const struct midr_range erratum_ac03_cpu_38_list[] = { MIDR_ALL_VERSIONS(MIDR_AMPERE1), @@ -869,6 +876,13 @@ const struct arm64_cpu_capabilities arm64_errata[] = { ERRATA_MIDR_RANGE_LIST(erratum_spec_unpriv_load_list), }, #endif +#ifdef CONFIG_AMPERE_ERRATUM_AC03_CPU_36 + { + .desc = "AmpereOne erratum AC03_CPU_36", + .capability = ARM64_WORKAROUND_AMPERE_AC03_CPU_36, + ERRATA_MIDR_RANGE_LIST(erratum_ac03_cpu_36_list), + }, +#endif #ifdef CONFIG_AMPERE_ERRATUM_AC03_CPU_38 { .desc = "AmpereOne erratum AC03_CPU_38", diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 772c1b008e437..f430fd5900d15 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -93,6 +93,7 @@ WORKAROUND_2077057 WORKAROUND_2457168 WORKAROUND_2645198 WORKAROUND_2658417 +WORKAROUND_AMPERE_AC03_CPU_36 WORKAROUND_AMPERE_AC03_CPU_38 WORKAROUND_TRBE_OVERWRITE_FILL_MODE WORKAROUND_TSB_FLUSH_FAILURE