From: Catalin Marinas <catalin.marinas@arm.com>
Date: Mon, 28 Oct 2019 16:12:40 +0000 (+0000)
Subject: Merge branch 'for-next/neoverse-n1-stale-instr' into for-next/core
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6a036afb5511418995359a9131dbea276758bd10;p=linux.git

Merge branch 'for-next/neoverse-n1-stale-instr' into for-next/core

Neoverse-N1 cores with the 'COHERENT_ICACHE' feature may fetch stale
instructions when software depends on prefetch-speculation-protection
instead of explicit synchronization. [0]

The workaround is to trap I-Cache maintenance and issue an
inner-shareable TLBI. The affected cores have a Coherent I-Cache, so the
I-Cache maintenance isn't necessary. The core tells user-space it can
skip it with CTR_EL0.DIC. We also have to trap this register to hide the
bit forcing DIC-aware user-space to perform the maintenance.

To avoid trapping all cache-maintenance, this workaround depends on
a firmware component that only traps I-cache maintenance from EL0 and
performs the workaround.

For user-space, the kernel's work is to trap CTR_EL0 to hide DIC, and
produce a fake IminLine. EL3 traps the now-necessary I-Cache maintenance
and performs the inner-shareable-TLBI that makes everything better.

[0] https://developer.arm.com/docs/sden885747/latest/arm-neoverse-n1-mp050-software-developer-errata-notice

* for-next/neoverse-n1-stale-instr:
  arm64: Silence clang warning on mismatched value/register sizes
  arm64: compat: Workaround Neoverse-N1 #1542419 for compat user-space
  arm64: Fake the IminLine size on systems affected by Neoverse-N1 #1542419
  arm64: errata: Hide CTR_EL0.DIC on systems affected by Neoverse-N1 #1542419
---

6a036afb5511418995359a9131dbea276758bd10
diff --cc arch/arm64/include/asm/cpucaps.h
index ac1dbca3d0cd3,f05afaec18cd1..1dc3c762fdcb9
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@@ -52,9 -52,8 +52,10 @@@
  #define ARM64_HAS_IRQ_PRIO_MASKING		42
  #define ARM64_HAS_DCPODP			43
  #define ARM64_WORKAROUND_1463225		44
 -#define ARM64_WORKAROUND_1542419		45
 +#define ARM64_WORKAROUND_CAVIUM_TX2_219_TVM	45
 +#define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
++#define ARM64_WORKAROUND_1542419		47
  
- #define ARM64_NCAPS				47
 -#define ARM64_NCAPS				46
++#define ARM64_NCAPS				48
  
  #endif /* __ASM_CPUCAPS_H */
diff --cc arch/arm64/kernel/cpu_errata.c
index 6c3b10a41bd85,3ae9b78b6d944..548e980ebb700
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@@ -624,30 -631,18 +632,42 @@@ check_branch_predictor(const struct arm
  	return (need_wa > 0);
  }
  
 +static const __maybe_unused struct midr_range tx2_family_cpus[] = {
 +	MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
 +	MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
 +	{},
 +};
 +
 +static bool __maybe_unused
 +needs_tx2_tvm_workaround(const struct arm64_cpu_capabilities *entry,
 +			 int scope)
 +{
 +	int i;
 +
 +	if (!is_affected_midr_range_list(entry, scope) ||
 +	    !is_hyp_mode_available())
 +		return false;
 +
 +	for_each_possible_cpu(i) {
 +		if (MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0) != 0)
 +			return true;
 +	}
 +
 +	return false;
 +}
 +
+ static bool __maybe_unused
+ has_neoverse_n1_erratum_1542419(const struct arm64_cpu_capabilities *entry,
+ 				int scope)
+ {
+ 	u32 midr = read_cpuid_id();
+ 	bool has_dic = read_cpuid_cachetype() & BIT(CTR_DIC_SHIFT);
+ 	const struct midr_range range = MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1);
+ 
+ 	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
+ 	return is_midr_in_range(midr, &range) && has_dic;
+ }
+ 
  #ifdef CONFIG_HARDEN_EL2_VECTORS
  
  static const struct midr_range arm64_harden_el2_vectors[] = {
@@@ -877,18 -872,15 +897,28 @@@ const struct arm64_cpu_capabilities arm
  		.matches = has_cortex_a76_erratum_1463225,
  	},
  #endif
 +#ifdef CONFIG_CAVIUM_TX2_ERRATUM_219
 +	{
 +		.desc = "Cavium ThunderX2 erratum 219 (KVM guest sysreg trapping)",
 +		.capability = ARM64_WORKAROUND_CAVIUM_TX2_219_TVM,
 +		ERRATA_MIDR_RANGE_LIST(tx2_family_cpus),
 +		.matches = needs_tx2_tvm_workaround,
 +	},
 +	{
 +		.desc = "Cavium ThunderX2 erratum 219 (PRFM removal)",
 +		.capability = ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM,
 +		ERRATA_MIDR_RANGE_LIST(tx2_family_cpus),
 +	},
++#endif
+ #ifdef CONFIG_ARM64_ERRATUM_1542419
+ 	{
+ 		/* we depend on the firmware portion for correctness */
+ 		.desc = "ARM erratum 1542419 (kernel portion)",
+ 		.capability = ARM64_WORKAROUND_1542419,
+ 		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
+ 		.matches = has_neoverse_n1_erratum_1542419,
+ 		.cpu_enable = cpu_enable_trap_ctr_access,
+ 	},
  #endif
  	{
  	}