* [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
@ 2023-04-12 12:55 Ivan T. Ivanov
2023-04-13 11:19 ` Mark Rutland
2023-04-17 3:07 ` Peng Fan
0 siblings, 2 replies; 9+ messages in thread
From: Ivan T. Ivanov @ 2023-04-12 12:55 UTC (permalink / raw)
To: Catalin Marinas, Will Deacon
Cc: Mark Brown, Mark Rutland, Shawn Guo, Dong Aisheng,
linux-arm-kernel, linux-imx, Ivan T. Ivanov
According to NXP errata document[1] i.MX8QuadMax SoC suffers from
serious cache coherence issue. It was also mentioned in initial
support[2] for imx8qm mek machine.
I chose to use an ALTERNATIVE() framework, instead downstream solution[3],
for this issue with the hope to reduce effect of this fix on unaffected
platforms.
Unfortunately I was unable to find a way to identify SoC ID using
registers. Boot CPU MIDR_EL1 is equal to 0x410fd034. So I fallback to
using devicetree compatible strings for this.
I know this fix is a suboptimal solution for affected machines, but I
haven't been able to come up with a less intrusive fix. And I hope once
TLB caches are invalidated any immediate attempt to invalidate them again
will be close to NOP operation (flush_tlb_kernel_range())
I have run few simple benchmarks and perf tests on affected and unaffected
machines and I was not able see any obvious issues. iMX8QM "performance"
was nearly doubled with 2 A72 bringed online.
Following is excerpt from NXP IMX8_1N94W "Mask Set Errata" document
Rev. 5, 3/2023. Just in case it gets lost somehow.
---
"ERR050104: Arm/A53: Cache coherency issue"
Description
Some maintenance operations exchanged between the A53 and A72
core clusters, involving some Translation Look-aside Buffer
Invalidate (TLBI) and Instruction Cache (IC) instructions can
be corrupted. The upper bits, above bit-35, of ARADDR and ACADDR
buses within in Arm A53 sub-system have been incorrectly connected.
Therefore ARADDR and ACADDR address bits above bit-35 should not
be used.
Workaround
The following software instructions are required to be downgraded
to TLBI VMALLE1IS: TLBI ASIDE1, TLBI ASIDE1IS, TLBI VAAE1,
TLBI VAAE1IS, TLBI VAALE1, TLBI VAALE1IS, TLBI VAE1, TLBI VAE1IS,
TLBI VALE1, TLBI VALE1IS
The following software instructions are required to be downgraded
to TLBI VMALLS12E1IS: TLBI IPAS2E1IS, TLBI IPAS2LE1IS
The following software instructions are required to be downgraded
to TLBI ALLE2IS: TLBI VAE2IS, TLBI VALE2IS.
The following software instructions are required to be downgraded
to TLBI ALLE3IS: TLBI VAE3IS, TLBI VALE3IS.
The following software instructions are required to be downgraded
to TLBI VMALLE1IS when the Force Broadcast (FB) bit [9] of the
Hypervisor Configuration Register (HCR_EL2) is set:
TLBI ASIDE1, TLBI VAAE1, TLBI VAALE1, TLBI VAE1, TLBI VALE1
The following software instruction is required to be downgraded
to IC IALLUIS: IC IVAU, Xt
Specifically for the IC IVAU, Xt downgrade, setting SCTLR_EL1.UCI
to 0 will disable EL0 access to this instruction. Any attempt to
execute from EL0 will generate an EL1 trap, where the downgrade to
IC ALLUIS can be implemented.
--
[1] https://www.nxp.com/docs/en/errata/IMX8_1N94W.pdf
[2] 307fd14d4b14 ("arm64: dts: imx: add imx8qm mek support")
[3] https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/include/asm/tlbflush.h#L19
Signed-off-by: Ivan T. Ivanov <iivanov@suse.de>
---
Documentation/arm64/silicon-errata.rst | 2 ++
arch/arm64/Kconfig | 10 ++++++++++
arch/arm64/include/asm/cpufeature.h | 3 ++-
arch/arm64/include/asm/tlbflush.h | 6 +++++-
arch/arm64/kernel/cpu_errata.c | 18 ++++++++++++++++++
arch/arm64/kernel/traps.c | 22 +++++++++++++++++++++-
arch/arm64/tools/cpucaps | 1 +
7 files changed, 59 insertions(+), 3 deletions(-)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index ec5f889d7681..fce231797184 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -175,6 +175,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
+----------------+-----------------+-----------------+-----------------------------+
+| Freescale/NXP | i.MX 8QuadMax | ERR050104 | NXP_IMX8QM_ERRATUM_ERR050104|
++----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Hisilicon | Hip0{5,6,7} | #161010101 | HISILICON_ERRATUM_161010101 |
+----------------+-----------------+-----------------+-----------------------------+
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1023e896d46b..437cb53f8753 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1159,6 +1159,16 @@ config SOCIONEXT_SYNQUACER_PREITS
If unsure, say Y.
+config NXP_IMX8QM_ERRATUM_ERR050104
+ bool "NXP iMX8QM: Workaround for Arm/A53 Cache coherency issue"
+ default n
+ help
+ Some maintenance operations exchanged between the A53 and A72 core
+ clusters, involving some Translation Look-aside Buffer Invalidate
+ (TLBI) and Instruction Cache (IC) instructions can be corrupted.
+
+ If unsure, say N.
+
endmenu # "ARM errata workarounds via the alternatives framework"
choice
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 6bf013fb110d..1ed648f7f29a 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
static inline bool system_supports_tlb_range(void)
{
return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
- cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
+ cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
+ !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
}
int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt);
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index 412a3b9a3c25..12055b859ce3 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -37,7 +37,11 @@
: : )
#define __TLBI_1(op, arg) asm (ARM64_ASM_PREAMBLE \
- "tlbi " #op ", %0\n" \
+ ALTERNATIVE("nop\n nop\n tlbi " #op ", %0", \
+ "tlbi vmalle1is\n dsb ish\n isb", \
+ ARM64_WORKAROUND_NXP_ERR050104) \
+ : : "r" (arg)); \
+ asm (ARM64_ASM_PREAMBLE \
ALTERNATIVE("nop\n nop", \
"dsb ish\n tlbi " #op ", %0", \
ARM64_WORKAROUND_REPEAT_TLBI, \
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 307faa2b4395..7b702a79bf60 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -8,6 +8,7 @@
#include <linux/arm-smccc.h>
#include <linux/types.h>
#include <linux/cpu.h>
+#include <linux/of.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/cpufeature.h>
@@ -55,6 +56,14 @@ is_kryo_midr(const struct arm64_cpu_capabilities *entry, int scope)
return model == entry->midr_range.model;
}
+static bool __maybe_unused
+is_imx8qm_soc(const struct arm64_cpu_capabilities *entry, int scope)
+{
+ WARN_ON(preemptible());
+
+ return of_machine_is_compatible("fsl,imx8qm");
+}
+
static bool
has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry,
int scope)
@@ -729,6 +738,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
MIDR_FIXED(MIDR_CPU_VAR_REV(1,1), BIT(25)),
.cpu_enable = cpu_clear_bf16_from_user_emulation,
},
+#endif
+#ifdef CONFIG_NXP_IMX8QM_ERRATUM_ERR050104
+ {
+ .desc = "NXP A53 cache coherency issue",
+ .capability = ARM64_WORKAROUND_NXP_ERR050104,
+ .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
+ .matches = is_imx8qm_soc,
+ .cpu_enable = cpu_enable_cache_maint_trap,
+ },
#endif
{
}
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 4a79ba100799..4858f8c86fd5 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -529,6 +529,26 @@ void do_el1_fpac(struct pt_regs *regs, unsigned long esr)
uaccess_ttbr0_disable(); \
}
+#define __user_instruction_cache_maint(address, res) \
+do { \
+ if (address >= TASK_SIZE_MAX) { \
+ res = -EFAULT; \
+ } else { \
+ uaccess_ttbr0_enable(); \
+ asm volatile ( \
+ "1:\n" \
+ ALTERNATIVE(" ic ivau, %1\n", \
+ " ic ialluis\n", \
+ ARM64_WORKAROUND_NXP_ERR050104) \
+ " mov %w0, #0\n" \
+ "2:\n" \
+ _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \
+ : "=r" (res) \
+ : "r" (address)); \
+ uaccess_ttbr0_disable(); \
+ } \
+} while (0)
+
static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
{
unsigned long tagged_address, address;
@@ -556,7 +576,7 @@ static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
__user_cache_maint("dc civac", address, ret);
break;
case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */
- __user_cache_maint("ic ivau", address, ret);
+ __user_instruction_cache_maint(address, ret);
break;
default:
force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 37b1340e9646..e225f1cd1005 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -90,3 +90,4 @@ WORKAROUND_NVIDIA_CARMEL_CNP
WORKAROUND_QCOM_FALKOR_E1003
WORKAROUND_REPEAT_TLBI
WORKAROUND_SPECULATIVE_AT
+WORKAROUND_NXP_ERR050104
--
2.35.3
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-12 12:55 [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue Ivan T. Ivanov
@ 2023-04-13 11:19 ` Mark Rutland
2023-04-14 11:36 ` Robin Murphy
2023-04-18 13:25 ` Ivan T. Ivanov
2023-04-17 3:07 ` Peng Fan
1 sibling, 2 replies; 9+ messages in thread
From: Mark Rutland @ 2023-04-13 11:19 UTC (permalink / raw)
To: Ivan T. Ivanov
Cc: Catalin Marinas, Will Deacon, Mark Brown, Shawn Guo,
Dong Aisheng, linux-arm-kernel, linux-imx
Hi,
On Wed, Apr 12, 2023 at 03:55:06PM +0300, Ivan T. Ivanov wrote:
> According to NXP errata document[1] i.MX8QuadMax SoC suffers from
> serious cache coherence issue. It was also mentioned in initial
> support[2] for imx8qm mek machine.
That's a fairly horrid bug.
> I chose to use an ALTERNATIVE() framework, instead downstream solution[3],
> for this issue with the hope to reduce effect of this fix on unaffected
> platforms.
>
> Unfortunately I was unable to find a way to identify SoC ID using
> registers. Boot CPU MIDR_EL1 is equal to 0x410fd034. So I fallback to
> using devicetree compatible strings for this.
How does this work with KVM?
VMs have no idea that the host platform is, and so will have no idea that this
erratum applies, so they're going to blow up spectacularly.
So we should probably be disabling KVM (or at the very least, printing a
gigantic warning).
> I know this fix is a suboptimal solution for affected machines, but I
> haven't been able to come up with a less intrusive fix. And I hope once
> TLB caches are invalidated any immediate attempt to invalidate them again
> will be close to NOP operation (flush_tlb_kernel_range())
>
> I have run few simple benchmarks and perf tests on affected and unaffected
> machines and I was not able see any obvious issues. iMX8QM "performance"
> was nearly doubled with 2 A72 bringed online.
>
> Following is excerpt from NXP IMX8_1N94W "Mask Set Errata" document
> Rev. 5, 3/2023. Just in case it gets lost somehow.
>
> ---
> "ERR050104: Arm/A53: Cache coherency issue"
>
> Description
>
> Some maintenance operations exchanged between the A53 and A72
> core clusters, involving some Translation Look-aside Buffer
> Invalidate (TLBI) and Instruction Cache (IC) instructions can
> be corrupted. The upper bits, above bit-35, of ARADDR and ACADDR
> buses within in Arm A53 sub-system have been incorrectly connected.
> Therefore ARADDR and ACADDR address bits above bit-35 should not
> be used.
>
> Workaround
>
> The following software instructions are required to be downgraded
> to TLBI VMALLE1IS: TLBI ASIDE1, TLBI ASIDE1IS, TLBI VAAE1,
> TLBI VAAE1IS, TLBI VAALE1, TLBI VAALE1IS, TLBI VAE1, TLBI VAE1IS,
> TLBI VALE1, TLBI VALE1IS
>
> The following software instructions are required to be downgraded
> to TLBI VMALLS12E1IS: TLBI IPAS2E1IS, TLBI IPAS2LE1IS
>
> The following software instructions are required to be downgraded
> to TLBI ALLE2IS: TLBI VAE2IS, TLBI VALE2IS.
>
> The following software instructions are required to be downgraded
> to TLBI ALLE3IS: TLBI VAE3IS, TLBI VALE3IS.
>
> The following software instructions are required to be downgraded
> to TLBI VMALLE1IS when the Force Broadcast (FB) bit [9] of the
> Hypervisor Configuration Register (HCR_EL2) is set:
> TLBI ASIDE1, TLBI VAAE1, TLBI VAALE1, TLBI VAE1, TLBI VALE1
>
> The following software instruction is required to be downgraded
> to IC IALLUIS: IC IVAU, Xt
>
> Specifically for the IC IVAU, Xt downgrade, setting SCTLR_EL1.UCI
> to 0 will disable EL0 access to this instruction. Any attempt to
> execute from EL0 will generate an EL1 trap, where the downgrade to
> IC ALLUIS can be implemented.
> --
>
> [1] https://www.nxp.com/docs/en/errata/IMX8_1N94W.pdf
> [2] 307fd14d4b14 ("arm64: dts: imx: add imx8qm mek support")
> [3] https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/include/asm/tlbflush.h#L19
>
> Signed-off-by: Ivan T. Ivanov <iivanov@suse.de>
> ---
> Documentation/arm64/silicon-errata.rst | 2 ++
> arch/arm64/Kconfig | 10 ++++++++++
> arch/arm64/include/asm/cpufeature.h | 3 ++-
> arch/arm64/include/asm/tlbflush.h | 6 +++++-
> arch/arm64/kernel/cpu_errata.c | 18 ++++++++++++++++++
> arch/arm64/kernel/traps.c | 22 +++++++++++++++++++++-
> arch/arm64/tools/cpucaps | 1 +
> 7 files changed, 59 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
> index ec5f889d7681..fce231797184 100644
> --- a/Documentation/arm64/silicon-errata.rst
> +++ b/Documentation/arm64/silicon-errata.rst
> @@ -175,6 +175,8 @@ stable kernels.
> +----------------+-----------------+-----------------+-----------------------------+
> | Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
> +----------------+-----------------+-----------------+-----------------------------+
> +| Freescale/NXP | i.MX 8QuadMax | ERR050104 | NXP_IMX8QM_ERRATUM_ERR050104|
> ++----------------+-----------------+-----------------+-----------------------------+
> +----------------+-----------------+-----------------+-----------------------------+
> | Hisilicon | Hip0{5,6,7} | #161010101 | HISILICON_ERRATUM_161010101 |
> +----------------+-----------------+-----------------+-----------------------------+
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1023e896d46b..437cb53f8753 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1159,6 +1159,16 @@ config SOCIONEXT_SYNQUACER_PREITS
>
> If unsure, say Y.
>
> +config NXP_IMX8QM_ERRATUM_ERR050104
> + bool "NXP iMX8QM: Workaround for Arm/A53 Cache coherency issue"
Please use the erratum number, e.g.
bool "NXP iMX8QM ERR050104: broken cache/tlb invalidation"
> + default n
> + help
> + Some maintenance operations exchanged between the A53 and A72 core
> + clusters, involving some Translation Look-aside Buffer Invalidate
> + (TLBI) and Instruction Cache (IC) instructions can be corrupted.
Likewise, please add a more compelte description here, e.g.
help
On iMX8QM, addresses above bit 35 are not broadcast correctly for
TLBI or IC operations, making TLBI and IC unreliable.
Work around this erratum by using TLBI *ALL*IS and IC IALLUIS
operations. EL0 use of IC IVAU is trapped and upgraded to IC IALLUIS.
> +
> + If unsure, say N.
> +
> endmenu # "ARM errata workarounds via the alternatives framework"
>
> choice
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 6bf013fb110d..1ed648f7f29a 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
> static inline bool system_supports_tlb_range(void)
> {
> return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
> - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
> + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
> + !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
> }
It'd be better to handle this in the detection of ARM64_HAS_TLB_RANGE, as we
have for CNP where has_useable_cnp() checks for ARM64_WORKAROUND_NVIDIA_CARMEL_CNP.
>
> int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt);
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index 412a3b9a3c25..12055b859ce3 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -37,7 +37,11 @@
> : : )
>
> #define __TLBI_1(op, arg) asm (ARM64_ASM_PREAMBLE \
> - "tlbi " #op ", %0\n" \
> + ALTERNATIVE("nop\n nop\n tlbi " #op ", %0", \
> + "tlbi vmalle1is\n dsb ish\n isb", \
> + ARM64_WORKAROUND_NXP_ERR050104) \
> + : : "r" (arg)); \
Why do you need the DSB ISH + ISB here? It's up to the caller to issue those,
and the ARM64_WORKAROUND_REPEAT_TLBI workaround only has DSB ISH to ensure that
the first op completes before the second is issued.
> + asm (ARM64_ASM_PREAMBLE \
> ALTERNATIVE("nop\n nop", \
> "dsb ish\n tlbi " #op ", %0", \
> ARM64_WORKAROUND_REPEAT_TLBI, \
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index 307faa2b4395..7b702a79bf60 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -8,6 +8,7 @@
> #include <linux/arm-smccc.h>
> #include <linux/types.h>
> #include <linux/cpu.h>
> +#include <linux/of.h>
> #include <asm/cpu.h>
> #include <asm/cputype.h>
> #include <asm/cpufeature.h>
> @@ -55,6 +56,14 @@ is_kryo_midr(const struct arm64_cpu_capabilities *entry, int scope)
> return model == entry->midr_range.model;
> }
>
> +static bool __maybe_unused
> +is_imx8qm_soc(const struct arm64_cpu_capabilities *entry, int scope)
> +{
> + WARN_ON(preemptible());
> +
> + return of_machine_is_compatible("fsl,imx8qm");
> +}
As above, what is going to be done for VMs, where this won't be present?
> +
> static bool
> has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry,
> int scope)
> @@ -729,6 +738,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
> MIDR_FIXED(MIDR_CPU_VAR_REV(1,1), BIT(25)),
> .cpu_enable = cpu_clear_bf16_from_user_emulation,
> },
> +#endif
> +#ifdef CONFIG_NXP_IMX8QM_ERRATUM_ERR050104
> + {
> + .desc = "NXP A53 cache coherency issue",
Please use the erratum number, i.e.
.desc = "NXP erratum ERR050104",
> + .capability = ARM64_WORKAROUND_NXP_ERR050104,
> + .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
> + .matches = is_imx8qm_soc,
> + .cpu_enable = cpu_enable_cache_maint_trap,
> + },
> #endif
> {
> }
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 4a79ba100799..4858f8c86fd5 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -529,6 +529,26 @@ void do_el1_fpac(struct pt_regs *regs, unsigned long esr)
> uaccess_ttbr0_disable(); \
> }
>
> +#define __user_instruction_cache_maint(address, res) \
> +do { \
> + if (address >= TASK_SIZE_MAX) { \
> + res = -EFAULT; \
> + } else { \
> + uaccess_ttbr0_enable(); \
> + asm volatile ( \
> + "1:\n" \
> + ALTERNATIVE(" ic ivau, %1\n", \
> + " ic ialluis\n", \
> + ARM64_WORKAROUND_NXP_ERR050104) \
> + " mov %w0, #0\n" \
> + "2:\n" \
> + _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \
> + : "=r" (res) \
> + : "r" (address)); \
> + uaccess_ttbr0_disable(); \
> + } \
> +} while (0)
> +
> static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
> {
> unsigned long tagged_address, address;
> @@ -556,7 +576,7 @@ static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
> __user_cache_maint("dc civac", address, ret);
> break;
> case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */
> - __user_cache_maint("ic ivau", address, ret);
> + __user_instruction_cache_maint(address, ret);
> break;
Hmm... this will silently change any 'IC IVAU' to never fault. That's probably
not the end of the world, since it's IMP-DEF whether IC would raise a
permission fault, but it is a change of behaviour.
It would be a bit simpler to handle this inline within the switch, e.g.
case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */
if (cpus_have_final_cap(ARM64_WORKAROUND_NXP_ERR050104)) {
asm volatile("ic ialluis");
ret = 0;
break;
}
__user_instruction_cache_maint(address, ret);
break;
... as that would avoid duplicating the bulk of the __user_cache_maint() macro.
> default:
> force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index 37b1340e9646..e225f1cd1005 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -90,3 +90,4 @@ WORKAROUND_NVIDIA_CARMEL_CNP
> WORKAROUND_QCOM_FALKOR_E1003
> WORKAROUND_REPEAT_TLBI
> WORKAROUND_SPECULATIVE_AT
> +WORKAROUND_NXP_ERR050104
These definitions are expected to be ordered alphabetically, so this should be
earlier in the list.
Thanks,
Mark.
> --
> 2.35.3
>
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-13 11:19 ` Mark Rutland
@ 2023-04-14 11:36 ` Robin Murphy
2023-04-17 15:35 ` Mark Rutland
2023-04-18 13:25 ` Ivan T. Ivanov
1 sibling, 1 reply; 9+ messages in thread
From: Robin Murphy @ 2023-04-14 11:36 UTC (permalink / raw)
To: Mark Rutland, Ivan T. Ivanov
Cc: Catalin Marinas, Will Deacon, Mark Brown, Shawn Guo,
Dong Aisheng, linux-arm-kernel, linux-imx
On 2023-04-13 12:19, Mark Rutland wrote:
[...]
>> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
>> index 6bf013fb110d..1ed648f7f29a 100644
>> --- a/arch/arm64/include/asm/cpufeature.h
>> +++ b/arch/arm64/include/asm/cpufeature.h
>> @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
>> static inline bool system_supports_tlb_range(void)
>> {
>> return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
>> - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
>> + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
>> + !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
>> }
>
> It'd be better to handle this in the detection of ARM64_HAS_TLB_RANGE, as we
> have for CNP where has_useable_cnp() checks for ARM64_WORKAROUND_NVIDIA_CARMEL_CNP.
It's not needed in either place, since neither Cortex-A53 or Cortex-A72
support FEAT_TLBIRANGE, so this could never be true on affected
platforms anyway.
Tangentially, I understand this platform has an SMMU[1], so I'd say it
would also be worth checking what SMMU_IDR0.BTM reports. With any luck
it might be 0, but if it's 1 then strictly it would want to be
overridden as part of a complete workaround as well. That wouldn't be a
practical issue right now, not least since the current Linux driver
doesn't even use BTM, but it's something which could need to be borne in
mind in future.
Robin.
[1]
https://lore.kernel.org/linux-arm-kernel/20210807104517.24066-1-peng.fan@oss.nxp.com/
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-12 12:55 [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue Ivan T. Ivanov
2023-04-13 11:19 ` Mark Rutland
@ 2023-04-17 3:07 ` Peng Fan
2023-04-17 14:48 ` Frank Li
1 sibling, 1 reply; 9+ messages in thread
From: Peng Fan @ 2023-04-17 3:07 UTC (permalink / raw)
To: Ivan T. Ivanov, Catalin Marinas, Will Deacon, frank.li
Cc: Mark Brown, Mark Rutland, Shawn Guo, Dong Aisheng,
linux-arm-kernel, linux-imx
+Frank, who had worked on downstream solution.
On 4/12/2023 8:55 PM, Ivan T. Ivanov wrote:
> According to NXP errata document[1] i.MX8QuadMax SoC suffers from
> serious cache coherence issue. It was also mentioned in initial
> support[2] for imx8qm mek machine.
>
> I chose to use an ALTERNATIVE() framework, instead downstream solution[3],
> for this issue with the hope to reduce effect of this fix on unaffected
> platforms.
>
> Unfortunately I was unable to find a way to identify SoC ID using
> registers. Boot CPU MIDR_EL1 is equal to 0x410fd034. So I fallback to
> using devicetree compatible strings for this.
>
> I know this fix is a suboptimal solution for affected machines, but I
> haven't been able to come up with a less intrusive fix. And I hope once
> TLB caches are invalidated any immediate attempt to invalidate them again
> will be close to NOP operation (flush_tlb_kernel_range())
>
> I have run few simple benchmarks and perf tests on affected and unaffected
> machines and I was not able see any obvious issues. iMX8QM "performance"
> was nearly doubled with 2 A72 bringed online.
>
> Following is excerpt from NXP IMX8_1N94W "Mask Set Errata" document
> Rev. 5, 3/2023. Just in case it gets lost somehow.
>
> ---
> "ERR050104: Arm/A53: Cache coherency issue"
>
> Description
>
> Some maintenance operations exchanged between the A53 and A72
> core clusters, involving some Translation Look-aside Buffer
> Invalidate (TLBI) and Instruction Cache (IC) instructions can
> be corrupted. The upper bits, above bit-35, of ARADDR and ACADDR
> buses within in Arm A53 sub-system have been incorrectly connected.
> Therefore ARADDR and ACADDR address bits above bit-35 should not
> be used.
>
> Workaround
>
> The following software instructions are required to be downgraded
> to TLBI VMALLE1IS: TLBI ASIDE1, TLBI ASIDE1IS, TLBI VAAE1,
> TLBI VAAE1IS, TLBI VAALE1, TLBI VAALE1IS, TLBI VAE1, TLBI VAE1IS,
> TLBI VALE1, TLBI VALE1IS
>
> The following software instructions are required to be downgraded
> to TLBI VMALLS12E1IS: TLBI IPAS2E1IS, TLBI IPAS2LE1IS
>
> The following software instructions are required to be downgraded
> to TLBI ALLE2IS: TLBI VAE2IS, TLBI VALE2IS.
>
> The following software instructions are required to be downgraded
> to TLBI ALLE3IS: TLBI VAE3IS, TLBI VALE3IS.
>
> The following software instructions are required to be downgraded
> to TLBI VMALLE1IS when the Force Broadcast (FB) bit [9] of the
> Hypervisor Configuration Register (HCR_EL2) is set:
> TLBI ASIDE1, TLBI VAAE1, TLBI VAALE1, TLBI VAE1, TLBI VALE1
>
> The following software instruction is required to be downgraded
> to IC IALLUIS: IC IVAU, Xt
>
> Specifically for the IC IVAU, Xt downgrade, setting SCTLR_EL1.UCI
> to 0 will disable EL0 access to this instruction. Any attempt to
> execute from EL0 will generate an EL1 trap, where the downgrade to
> IC ALLUIS can be implemented.
> --
>
> [1] https://www.nxp.com/docs/en/errata/IMX8_1N94W.pdf
> [2] 307fd14d4b14 ("arm64: dts: imx: add imx8qm mek support")
> [3] https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/include/asm/tlbflush.h#L19
>
> Signed-off-by: Ivan T. Ivanov <iivanov@suse.de>
> ---
> Documentation/arm64/silicon-errata.rst | 2 ++
> arch/arm64/Kconfig | 10 ++++++++++
> arch/arm64/include/asm/cpufeature.h | 3 ++-
> arch/arm64/include/asm/tlbflush.h | 6 +++++-
> arch/arm64/kernel/cpu_errata.c | 18 ++++++++++++++++++
> arch/arm64/kernel/traps.c | 22 +++++++++++++++++++++-
> arch/arm64/tools/cpucaps | 1 +
> 7 files changed, 59 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
> index ec5f889d7681..fce231797184 100644
> --- a/Documentation/arm64/silicon-errata.rst
> +++ b/Documentation/arm64/silicon-errata.rst
> @@ -175,6 +175,8 @@ stable kernels.
> +----------------+-----------------+-----------------+-----------------------------+
> | Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
> +----------------+-----------------+-----------------+-----------------------------+
> +| Freescale/NXP | i.MX 8QuadMax | ERR050104 | NXP_IMX8QM_ERRATUM_ERR050104|
> ++----------------+-----------------+-----------------+-----------------------------+
> +----------------+-----------------+-----------------+-----------------------------+
> | Hisilicon | Hip0{5,6,7} | #161010101 | HISILICON_ERRATUM_161010101 |
> +----------------+-----------------+-----------------+-----------------------------+
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1023e896d46b..437cb53f8753 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1159,6 +1159,16 @@ config SOCIONEXT_SYNQUACER_PREITS
>
> If unsure, say Y.
>
> +config NXP_IMX8QM_ERRATUM_ERR050104
> + bool "NXP iMX8QM: Workaround for Arm/A53 Cache coherency issue"
> + default n
> + help
> + Some maintenance operations exchanged between the A53 and A72 core
> + clusters, involving some Translation Look-aside Buffer Invalidate
> + (TLBI) and Instruction Cache (IC) instructions can be corrupted.
> +
> + If unsure, say N.
> +
> endmenu # "ARM errata workarounds via the alternatives framework"
>
> choice
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 6bf013fb110d..1ed648f7f29a 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
> static inline bool system_supports_tlb_range(void)
> {
> return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
> - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
> + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
> + !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
> }
>
> int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt);
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index 412a3b9a3c25..12055b859ce3 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -37,7 +37,11 @@
> : : )
>
> #define __TLBI_1(op, arg) asm (ARM64_ASM_PREAMBLE \
> - "tlbi " #op ", %0\n" \
> + ALTERNATIVE("nop\n nop\n tlbi " #op ", %0", \
> + "tlbi vmalle1is\n dsb ish\n isb", \
> + ARM64_WORKAROUND_NXP_ERR050104) \
> + : : "r" (arg)); \
> + asm (ARM64_ASM_PREAMBLE \
> ALTERNATIVE("nop\n nop", \
> "dsb ish\n tlbi " #op ", %0", \
> ARM64_WORKAROUND_REPEAT_TLBI, \
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index 307faa2b4395..7b702a79bf60 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -8,6 +8,7 @@
> #include <linux/arm-smccc.h>
> #include <linux/types.h>
> #include <linux/cpu.h>
> +#include <linux/of.h>
> #include <asm/cpu.h>
> #include <asm/cputype.h>
> #include <asm/cpufeature.h>
> @@ -55,6 +56,14 @@ is_kryo_midr(const struct arm64_cpu_capabilities *entry, int scope)
> return model == entry->midr_range.model;
> }
>
> +static bool __maybe_unused
> +is_imx8qm_soc(const struct arm64_cpu_capabilities *entry, int scope)
> +{
> + WARN_ON(preemptible());
> +
> + return of_machine_is_compatible("fsl,imx8qm");
> +}
> +
> static bool
> has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry,
> int scope)
> @@ -729,6 +738,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
> MIDR_FIXED(MIDR_CPU_VAR_REV(1,1), BIT(25)),
> .cpu_enable = cpu_clear_bf16_from_user_emulation,
> },
> +#endif
> +#ifdef CONFIG_NXP_IMX8QM_ERRATUM_ERR050104
> + {
> + .desc = "NXP A53 cache coherency issue",
> + .capability = ARM64_WORKAROUND_NXP_ERR050104,
> + .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
> + .matches = is_imx8qm_soc,
> + .cpu_enable = cpu_enable_cache_maint_trap,
> + },
> #endif
> {
> }
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 4a79ba100799..4858f8c86fd5 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -529,6 +529,26 @@ void do_el1_fpac(struct pt_regs *regs, unsigned long esr)
> uaccess_ttbr0_disable(); \
> }
>
> +#define __user_instruction_cache_maint(address, res) \
> +do { \
> + if (address >= TASK_SIZE_MAX) { \
> + res = -EFAULT; \
> + } else { \
> + uaccess_ttbr0_enable(); \
> + asm volatile ( \
> + "1:\n" \
> + ALTERNATIVE(" ic ivau, %1\n", \
> + " ic ialluis\n", \
> + ARM64_WORKAROUND_NXP_ERR050104) \
> + " mov %w0, #0\n" \
> + "2:\n" \
> + _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \
> + : "=r" (res) \
> + : "r" (address)); \
> + uaccess_ttbr0_disable(); \
> + } \
> +} while (0)
> +
> static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
> {
> unsigned long tagged_address, address;
> @@ -556,7 +576,7 @@ static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
> __user_cache_maint("dc civac", address, ret);
> break;
> case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */
> - __user_cache_maint("ic ivau", address, ret);
> + __user_instruction_cache_maint(address, ret);
> break;
> default:
> force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index 37b1340e9646..e225f1cd1005 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -90,3 +90,4 @@ WORKAROUND_NVIDIA_CARMEL_CNP
> WORKAROUND_QCOM_FALKOR_E1003
> WORKAROUND_REPEAT_TLBI
> WORKAROUND_SPECULATIVE_AT
> +WORKAROUND_NXP_ERR050104
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^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-17 3:07 ` Peng Fan
@ 2023-04-17 14:48 ` Frank Li
0 siblings, 0 replies; 9+ messages in thread
From: Frank Li @ 2023-04-17 14:48 UTC (permalink / raw)
To: Peng Fan (OSS), Ivan T. Ivanov, Catalin Marinas, Will Deacon, Jason Liu
Cc: Mark Brown, Mark Rutland, Shawn Guo, Aisheng Dong,
linux-arm-kernel, dl-linux-imx
> -----Original Message-----
> From: Peng Fan (OSS) <peng.fan@oss.nxp.com>
> Sent: Sunday, April 16, 2023 10:08 PM
> To: Ivan T. Ivanov <iivanov@suse.de>; Catalin Marinas
> <catalin.marinas@arm.com>; Will Deacon <will@kernel.org>; Frank Li
> <frank.li@nxp.com>
> Cc: Mark Brown <broonie@kernel.org>; Mark Rutland
> <mark.rutland@arm.com>; Shawn Guo <shawnguo@kernel.org>; Aisheng
> Dong <aisheng.dong@nxp.com>; linux-arm-kernel@lists.infradead.org; dl-
> linux-imx <linux-imx@nxp.com>
> Subject: Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53
> Cache coherency issue
>
> +Frank, who had worked on downstream solution.
+ Jason Liu, who actually work on this.
Best regards
Frank Li
>
> On 4/12/2023 8:55 PM, Ivan T. Ivanov wrote:
> > According to NXP errata document[1] i.MX8QuadMax SoC suffers from
> > serious cache coherence issue. It was also mentioned in initial
> > support[2] for imx8qm mek machine.
> >
> > I chose to use an ALTERNATIVE() framework, instead downstream
> solution[3],
> > for this issue with the hope to reduce effect of this fix on unaffected
> > platforms.
> >
> > Unfortunately I was unable to find a way to identify SoC ID using
> > registers. Boot CPU MIDR_EL1 is equal to 0x410fd034. So I fallback to
> > using devicetree compatible strings for this.
> >
> > I know this fix is a suboptimal solution for affected machines, but I
> > haven't been able to come up with a less intrusive fix. And I hope once
> > TLB caches are invalidated any immediate attempt to invalidate them again
> > will be close to NOP operation (flush_tlb_kernel_range())
> >
> > I have run few simple benchmarks and perf tests on affected and
> unaffected
> > machines and I was not able see any obvious issues. iMX8QM
> "performance"
> > was nearly doubled with 2 A72 bringed online.
> >
> > Following is excerpt from NXP IMX8_1N94W "Mask Set Errata" document
> > Rev. 5, 3/2023. Just in case it gets lost somehow.
> >
> > ---
> > "ERR050104: Arm/A53: Cache coherency issue"
> >
> > Description
> >
> > Some maintenance operations exchanged between the A53 and A72
> > core clusters, involving some Translation Look-aside Buffer
> > Invalidate (TLBI) and Instruction Cache (IC) instructions can
> > be corrupted. The upper bits, above bit-35, of ARADDR and ACADDR
> > buses within in Arm A53 sub-system have been incorrectly connected.
> > Therefore ARADDR and ACADDR address bits above bit-35 should not
> > be used.
> >
> > Workaround
> >
> > The following software instructions are required to be downgraded
> > to TLBI VMALLE1IS: TLBI ASIDE1, TLBI ASIDE1IS, TLBI VAAE1,
> > TLBI VAAE1IS, TLBI VAALE1, TLBI VAALE1IS, TLBI VAE1, TLBI VAE1IS,
> > TLBI VALE1, TLBI VALE1IS
> >
> > The following software instructions are required to be downgraded
> > to TLBI VMALLS12E1IS: TLBI IPAS2E1IS, TLBI IPAS2LE1IS
> >
> > The following software instructions are required to be downgraded
> > to TLBI ALLE2IS: TLBI VAE2IS, TLBI VALE2IS.
> >
> > The following software instructions are required to be downgraded
> > to TLBI ALLE3IS: TLBI VAE3IS, TLBI VALE3IS.
> >
> > The following software instructions are required to be downgraded
> > to TLBI VMALLE1IS when the Force Broadcast (FB) bit [9] of the
> > Hypervisor Configuration Register (HCR_EL2) is set:
> > TLBI ASIDE1, TLBI VAAE1, TLBI VAALE1, TLBI VAE1, TLBI VALE1
> >
> > The following software instruction is required to be downgraded
> > to IC IALLUIS: IC IVAU, Xt
> >
> > Specifically for the IC IVAU, Xt downgrade, setting SCTLR_EL1.UCI
> > to 0 will disable EL0 access to this instruction. Any attempt to
> > execute from EL0 will generate an EL1 trap, where the downgrade to
> > IC ALLUIS can be implemented.
> > --
> >
> > [1] https://www.nxp.com/docs/en/errata/IMX8_1N94W.pdf
> > [2] 307fd14d4b14 ("arm64: dts: imx: add imx8qm mek support")
> > [3] https://github.com/nxp-imx/linux-imx/blob/lf-
> 6.1.y/arch/arm64/include/asm/tlbflush.h#L19
> >
> > Signed-off-by: Ivan T. Ivanov <iivanov@suse.de>
> > ---
> > Documentation/arm64/silicon-errata.rst | 2 ++
> > arch/arm64/Kconfig | 10 ++++++++++
> > arch/arm64/include/asm/cpufeature.h | 3 ++-
> > arch/arm64/include/asm/tlbflush.h | 6 +++++-
> > arch/arm64/kernel/cpu_errata.c | 18 ++++++++++++++++++
> > arch/arm64/kernel/traps.c | 22 +++++++++++++++++++++-
> > arch/arm64/tools/cpucaps | 1 +
> > 7 files changed, 59 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/arm64/silicon-errata.rst
> b/Documentation/arm64/silicon-errata.rst
> > index ec5f889d7681..fce231797184 100644
> > --- a/Documentation/arm64/silicon-errata.rst
> > +++ b/Documentation/arm64/silicon-errata.rst
> > @@ -175,6 +175,8 @@ stable kernels.
> > +----------------+-----------------+-----------------+-----------------------------+
> > | Freescale/NXP | LS2080A/LS1043A | A-008585 |
> FSL_ERRATUM_A008585 |
> > +----------------+-----------------+-----------------+-----------------------------+
> > +| Freescale/NXP | i.MX 8QuadMax | ERR050104 |
> NXP_IMX8QM_ERRATUM_ERR050104|
> > ++----------------+-----------------+-----------------+-----------------------------+
> > +----------------+-----------------+-----------------+-----------------------------+
> > | Hisilicon | Hip0{5,6,7} | #161010101 |
> HISILICON_ERRATUM_161010101 |
> > +----------------+-----------------+-----------------+-----------------------------+
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 1023e896d46b..437cb53f8753 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -1159,6 +1159,16 @@ config SOCIONEXT_SYNQUACER_PREITS
> >
> > If unsure, say Y.
> >
> > +config NXP_IMX8QM_ERRATUM_ERR050104
> > + bool "NXP iMX8QM: Workaround for Arm/A53 Cache coherency
> issue"
> > + default n
> > + help
> > + Some maintenance operations exchanged between the A53 and
> A72 core
> > + clusters, involving some Translation Look-aside Buffer Invalidate
> > + (TLBI) and Instruction Cache (IC) instructions can be corrupted.
> > +
> > + If unsure, say N.
> > +
> > endmenu # "ARM errata workarounds via the alternatives framework"
> >
> > choice
> > diff --git a/arch/arm64/include/asm/cpufeature.h
> b/arch/arm64/include/asm/cpufeature.h
> > index 6bf013fb110d..1ed648f7f29a 100644
> > --- a/arch/arm64/include/asm/cpufeature.h
> > +++ b/arch/arm64/include/asm/cpufeature.h
> > @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
> > static inline bool system_supports_tlb_range(void)
> > {
> > return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
> > - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
> > + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
> > +
> !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
> > }
> >
> > int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt);
> > diff --git a/arch/arm64/include/asm/tlbflush.h
> b/arch/arm64/include/asm/tlbflush.h
> > index 412a3b9a3c25..12055b859ce3 100644
> > --- a/arch/arm64/include/asm/tlbflush.h
> > +++ b/arch/arm64/include/asm/tlbflush.h
> > @@ -37,7 +37,11 @@
> > : : )
> >
> > #define __TLBI_1(op, arg) asm (ARM64_ASM_PREAMBLE
> \
> > - "tlbi " #op ", %0\n" \
> > + ALTERNATIVE("nop\n nop\n tlbi " #op ", %0", \
> > + "tlbi vmalle1is\n dsb ish\n isb", \
> > + ARM64_WORKAROUND_NXP_ERR050104)
> \
> > + : : "r" (arg)); \
> > + asm (ARM64_ASM_PREAMBLE
> \
> > ALTERNATIVE("nop\n nop", \
> > "dsb ish\n tlbi " #op ", %0", \
> > ARM64_WORKAROUND_REPEAT_TLBI,
> \
> > diff --git a/arch/arm64/kernel/cpu_errata.c
> b/arch/arm64/kernel/cpu_errata.c
> > index 307faa2b4395..7b702a79bf60 100644
> > --- a/arch/arm64/kernel/cpu_errata.c
> > +++ b/arch/arm64/kernel/cpu_errata.c
> > @@ -8,6 +8,7 @@
> > #include <linux/arm-smccc.h>
> > #include <linux/types.h>
> > #include <linux/cpu.h>
> > +#include <linux/of.h>
> > #include <asm/cpu.h>
> > #include <asm/cputype.h>
> > #include <asm/cpufeature.h>
> > @@ -55,6 +56,14 @@ is_kryo_midr(const struct arm64_cpu_capabilities
> *entry, int scope)
> > return model == entry->midr_range.model;
> > }
> >
> > +static bool __maybe_unused
> > +is_imx8qm_soc(const struct arm64_cpu_capabilities *entry, int scope)
> > +{
> > + WARN_ON(preemptible());
> > +
> > + return of_machine_is_compatible("fsl,imx8qm");
> > +}
> > +
> > static bool
> > has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry,
> > int scope)
> > @@ -729,6 +738,15 @@ const struct arm64_cpu_capabilities arm64_errata[]
> = {
> > MIDR_FIXED(MIDR_CPU_VAR_REV(1,1), BIT(25)),
> > .cpu_enable = cpu_clear_bf16_from_user_emulation,
> > },
> > +#endif
> > +#ifdef CONFIG_NXP_IMX8QM_ERRATUM_ERR050104
> > + {
> > + .desc = "NXP A53 cache coherency issue",
> > + .capability = ARM64_WORKAROUND_NXP_ERR050104,
> > + .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
> > + .matches = is_imx8qm_soc,
> > + .cpu_enable = cpu_enable_cache_maint_trap,
> > + },
> > #endif
> > {
> > }
> > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> > index 4a79ba100799..4858f8c86fd5 100644
> > --- a/arch/arm64/kernel/traps.c
> > +++ b/arch/arm64/kernel/traps.c
> > @@ -529,6 +529,26 @@ void do_el1_fpac(struct pt_regs *regs, unsigned
> long esr)
> > uaccess_ttbr0_disable(); \
> > }
> >
> > +#define __user_instruction_cache_maint(address, res) \
> > +do { \
> > + if (address >= TASK_SIZE_MAX) { \
> > + res = -EFAULT; \
> > + } else { \
> > + uaccess_ttbr0_enable(); \
> > + asm volatile ( \
> > + "1:\n" \
> > + ALTERNATIVE(" ic ivau, %1\n", \
> > + " ic ialluis\n", \
> > + ARM64_WORKAROUND_NXP_ERR050104)
> \
> > + " mov %w0, #0\n" \
> > + "2:\n" \
> > + _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \
> > + : "=r" (res) \
> > + : "r" (address)); \
> > + uaccess_ttbr0_disable(); \
> > + } \
> > +} while (0)
> > +
> > static void user_cache_maint_handler(unsigned long esr, struct pt_regs
> *regs)
> > {
> > unsigned long tagged_address, address;
> > @@ -556,7 +576,7 @@ static void user_cache_maint_handler(unsigned
> long esr, struct pt_regs *regs)
> > __user_cache_maint("dc civac", address, ret);
> > break;
> > case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */
> > - __user_cache_maint("ic ivau", address, ret);
> > + __user_instruction_cache_maint(address, ret);
> > break;
> > default:
> > force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
> > diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> > index 37b1340e9646..e225f1cd1005 100644
> > --- a/arch/arm64/tools/cpucaps
> > +++ b/arch/arm64/tools/cpucaps
> > @@ -90,3 +90,4 @@ WORKAROUND_NVIDIA_CARMEL_CNP
> > WORKAROUND_QCOM_FALKOR_E1003
> > WORKAROUND_REPEAT_TLBI
> > WORKAROUND_SPECULATIVE_AT
> > +WORKAROUND_NXP_ERR050104
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-14 11:36 ` Robin Murphy
@ 2023-04-17 15:35 ` Mark Rutland
2023-04-18 16:54 ` Ivan T. Ivanov
0 siblings, 1 reply; 9+ messages in thread
From: Mark Rutland @ 2023-04-17 15:35 UTC (permalink / raw)
To: Robin Murphy
Cc: Ivan T. Ivanov, Catalin Marinas, Will Deacon, Mark Brown,
Shawn Guo, Dong Aisheng, linux-arm-kernel, linux-imx
On Fri, Apr 14, 2023 at 12:36:53PM +0100, Robin Murphy wrote:
> On 2023-04-13 12:19, Mark Rutland wrote:
> [...]
> > > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> > > index 6bf013fb110d..1ed648f7f29a 100644
> > > --- a/arch/arm64/include/asm/cpufeature.h
> > > +++ b/arch/arm64/include/asm/cpufeature.h
> > > @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
> > > static inline bool system_supports_tlb_range(void)
> > > {
> > > return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
> > > - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
> > > + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
> > > + !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
> > > }
> >
> > It'd be better to handle this in the detection of ARM64_HAS_TLB_RANGE, as we
> > have for CNP where has_useable_cnp() checks for ARM64_WORKAROUND_NVIDIA_CARMEL_CNP.
>
> It's not needed in either place, since neither Cortex-A53 or Cortex-A72
> support FEAT_TLBIRANGE, so this could never be true on affected platforms
> anyway.
Ah, even better -- we can just drop it.
> Tangentially, I understand this platform has an SMMU[1], so I'd say it would
> also be worth checking what SMMU_IDR0.BTM reports. With any luck it might be
> 0, but if it's 1 then strictly it would want to be overridden as part of a
> complete workaround as well. That wouldn't be a practical issue right now,
> not least since the current Linux driver doesn't even use BTM, but it's
> something which could need to be borne in mind in future.
Absolutely.
Mark.
>
> Robin.
>
> [1] https://lore.kernel.org/linux-arm-kernel/20210807104517.24066-1-peng.fan@oss.nxp.com/
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-13 11:19 ` Mark Rutland
2023-04-14 11:36 ` Robin Murphy
@ 2023-04-18 13:25 ` Ivan T. Ivanov
1 sibling, 0 replies; 9+ messages in thread
From: Ivan T. Ivanov @ 2023-04-18 13:25 UTC (permalink / raw)
To: Mark Rutland
Cc: Catalin Marinas, Will Deacon, Mark Brown, Shawn Guo,
Dong Aisheng, linux-arm-kernel, linux-imx
On 04-13 12:19, Mark Rutland wrote:
> >
> > Unfortunately I was unable to find a way to identify SoC ID using
> > registers. Boot CPU MIDR_EL1 is equal to 0x410fd034. So I fallback to
> > using devicetree compatible strings for this.
>
> How does this work with KVM?
>
> VMs have no idea that the host platform is, and so will have no idea that this
> erratum applies, so they're going to blow up spectacularly.
I don't think this platform it is supposed to run KVM guests, but
who knows?! Someone suggested using SMBIOS tables or something around
this, but I am not sure how reliable way this is.
>
> So we should probably be disabling KVM (or at the very least, printing a
> gigantic warning).
I will see if I can come up with something. Suggestions are of course
welcomed.
>
> >
> > +config NXP_IMX8QM_ERRATUM_ERR050104
> > + bool "NXP iMX8QM: Workaround for Arm/A53 Cache coherency issue"
>
> Please use the erratum number, e.g.
>
Ok.
> bool "NXP iMX8QM ERR050104: broken cache/tlb invalidation"
>
> > + default n
> > + help
> > + Some maintenance operations exchanged between the A53 and A72 core
> > + clusters, involving some Translation Look-aside Buffer Invalidate
> > + (TLBI) and Instruction Cache (IC) instructions can be corrupted.
>
> Likewise, please add a more compelte description here, e.g.
>
> help
> On iMX8QM, addresses above bit 35 are not broadcast correctly for
> TLBI or IC operations, making TLBI and IC unreliable.
>
> Work around this erratum by using TLBI *ALL*IS and IC IALLUIS
> operations. EL0 use of IC IVAU is trapped and upgraded to IC IALLUIS.
>
Ok.
> > +
> > + If unsure, say N.
> > +
> > endmenu # "ARM errata workarounds via the alternatives framework"
> >
> > choice
> > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> > index 6bf013fb110d..1ed648f7f29a 100644
> > --- a/arch/arm64/include/asm/cpufeature.h
> > +++ b/arch/arm64/include/asm/cpufeature.h
> > @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
> > static inline bool system_supports_tlb_range(void)
> > {
> > return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
> > - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
> > + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
> > + !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
> > }
>
> It'd be better to handle this in the detection of ARM64_HAS_TLB_RANGE, as we
> have for CNP where has_useable_cnp() checks for ARM64_WORKAROUND_NVIDIA_CARMEL_CNP.
Thanks, I will rework this.
>
> >
> > int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt);
> > diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> > index 412a3b9a3c25..12055b859ce3 100644
> > --- a/arch/arm64/include/asm/tlbflush.h
> > +++ b/arch/arm64/include/asm/tlbflush.h
> > @@ -37,7 +37,11 @@
> > : : )
> >
> > #define __TLBI_1(op, arg) asm (ARM64_ASM_PREAMBLE \
> > - "tlbi " #op ", %0\n" \
> > + ALTERNATIVE("nop\n nop\n tlbi " #op ", %0", \
> > + "tlbi vmalle1is\n dsb ish\n isb", \
> > + ARM64_WORKAROUND_NXP_ERR050104) \
> > + : : "r" (arg)); \
>
> Why do you need the DSB ISH + ISB here? It's up to the caller to issue those,
> and the ARM64_WORKAROUND_REPEAT_TLBI workaround only has DSB ISH to ensure that
> the first op completes before the second is issued.
Right, perhaps I was gone too far here :-)
>
> > + asm (ARM64_ASM_PREAMBLE \
> > ALTERNATIVE("nop\n nop", \
> > "dsb ish\n tlbi " #op ", %0", \
> > ARM64_WORKAROUND_REPEAT_TLBI, \
> > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> > index 307faa2b4395..7b702a79bf60 100644
> > --- a/arch/arm64/kernel/cpu_errata.c
> > +++ b/arch/arm64/kernel/cpu_errata.c
> > @@ -8,6 +8,7 @@
> > #include <linux/arm-smccc.h>
> > #include <linux/types.h>
> > #include <linux/cpu.h>
> > +#include <linux/of.h>
> > #include <asm/cpu.h>
> > #include <asm/cputype.h>
> > #include <asm/cpufeature.h>
> > @@ -55,6 +56,14 @@ is_kryo_midr(const struct arm64_cpu_capabilities *entry, int scope)
> > return model == entry->midr_range.model;
> > }
> >
> > +static bool __maybe_unused
> > +is_imx8qm_soc(const struct arm64_cpu_capabilities *entry, int scope)
> > +{
> > + WARN_ON(preemptible());
> > +
> > + return of_machine_is_compatible("fsl,imx8qm");
> > +}
>
> As above, what is going to be done for VMs, where this won't be present?
As I said, not sure this is usable for running VM's, but I am open for
suggestions. Maybe NXP has some register which could be used for SoC
identification, but judging by downstream implementation there is none.
>
> > +
> > static bool
> > has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry,
> > int scope)
> > @@ -729,6 +738,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
> > MIDR_FIXED(MIDR_CPU_VAR_REV(1,1), BIT(25)),
> > .cpu_enable = cpu_clear_bf16_from_user_emulation,
> > },
> > +#endif
> > +#ifdef CONFIG_NXP_IMX8QM_ERRATUM_ERR050104
> > + {
> > + .desc = "NXP A53 cache coherency issue",
>
> Please use the erratum number, i.e.
>
> .desc = "NXP erratum ERR050104",
Ok.
>
> > + .capability = ARM64_WORKAROUND_NXP_ERR050104,
> > + .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
> > + .matches = is_imx8qm_soc,
> > + .cpu_enable = cpu_enable_cache_maint_trap,
> > + },
> > #endif
> > {
> > }
> > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> > index 4a79ba100799..4858f8c86fd5 100644
> > --- a/arch/arm64/kernel/traps.c
> > +++ b/arch/arm64/kernel/traps.c
> > @@ -529,6 +529,26 @@ void do_el1_fpac(struct pt_regs *regs, unsigned long esr)
> > uaccess_ttbr0_disable(); \
> > }
> >
> > +#define __user_instruction_cache_maint(address, res) \
> > +do { \
> > + if (address >= TASK_SIZE_MAX) { \
> > + res = -EFAULT; \
> > + } else { \
> > + uaccess_ttbr0_enable(); \
> > + asm volatile ( \
> > + "1:\n" \
> > + ALTERNATIVE(" ic ivau, %1\n", \
> > + " ic ialluis\n", \
> > + ARM64_WORKAROUND_NXP_ERR050104) \
> > + " mov %w0, #0\n" \
> > + "2:\n" \
> > + _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \
> > + : "=r" (res) \
> > + : "r" (address)); \
> > + uaccess_ttbr0_disable(); \
> > + } \
> > +} while (0)
> > +
> > static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
> > {
> > unsigned long tagged_address, address;
> > @@ -556,7 +576,7 @@ static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
> > __user_cache_maint("dc civac", address, ret);
> > break;
> > case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */
> > - __user_cache_maint("ic ivau", address, ret);
> > + __user_instruction_cache_maint(address, ret);
> > break;
>
> Hmm... this will silently change any 'IC IVAU' to never fault. That's probably
> not the end of the world, since it's IMP-DEF whether IC would raise a
> permission fault, but it is a change of behaviour.
>
> It would be a bit simpler to handle this inline within the switch, e.g.
>
> case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */
> if (cpus_have_final_cap(ARM64_WORKAROUND_NXP_ERR050104)) {
> asm volatile("ic ialluis");
> ret = 0;
> break;
> }
> __user_instruction_cache_maint(address, ret);
> break;
>
> ... as that would avoid duplicating the bulk of the __user_cache_maint() macro.
Ok.
>
>
> > default:
> > force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
> > diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> > index 37b1340e9646..e225f1cd1005 100644
> > --- a/arch/arm64/tools/cpucaps
> > +++ b/arch/arm64/tools/cpucaps
> > @@ -90,3 +90,4 @@ WORKAROUND_NVIDIA_CARMEL_CNP
> > WORKAROUND_QCOM_FALKOR_E1003
> > WORKAROUND_REPEAT_TLBI
> > WORKAROUND_SPECULATIVE_AT
> > +WORKAROUND_NXP_ERR050104
>
> These definitions are expected to be ordered alphabetically, so this should be
> earlier in the list.
>
Ok. Thanks!
Ivan
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-17 15:35 ` Mark Rutland
@ 2023-04-18 16:54 ` Ivan T. Ivanov
2023-04-20 17:02 ` Robin Murphy
0 siblings, 1 reply; 9+ messages in thread
From: Ivan T. Ivanov @ 2023-04-18 16:54 UTC (permalink / raw)
To: Mark Rutland
Cc: Robin Murphy, Catalin Marinas, Will Deacon, Mark Brown,
Shawn Guo, Dong Aisheng, linux-arm-kernel, linux-imx
On 04-17 16:35, Mark Rutland wrote:
> > > > @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
> > > > static inline bool system_supports_tlb_range(void)
> > > > {
> > > > return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
> > > > - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
> > > > + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
> > > > + !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
> > > > }
> > >
> > > It'd be better to handle this in the detection of ARM64_HAS_TLB_RANGE, as we
> > > have for CNP where has_useable_cnp() checks for ARM64_WORKAROUND_NVIDIA_CARMEL_CNP.
> >
> > It's not needed in either place, since neither Cortex-A53 or Cortex-A72
> > support FEAT_TLBIRANGE, so this could never be true on affected platforms
> > anyway.
>
> Ah, even better -- we can just drop it.
Ok.
>
> > Tangentially, I understand this platform has an SMMU[1], so I'd say it would
> > also be worth checking what SMMU_IDR0.BTM reports. With any luck it might be
> > 0, but if it's 1 then strictly it would want to be overridden as part of a
> > complete workaround as well. That wouldn't be a practical issue right now,
> > not least since the current Linux driver doesn't even use BTM, but it's
> > something which could need to be borne in mind in future.
>
> Absolutely.
I don't completely understand implication of this, but for SMMU inside
iMX8QM report that "Broadcast TLB maintenance is supported"
Regards,
Ivan
>
> >
> > [1] https://lore.kernel.org/linux-arm-kernel/20210807104517.24066-1-peng.fan@oss.nxp.com/
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^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue
2023-04-18 16:54 ` Ivan T. Ivanov
@ 2023-04-20 17:02 ` Robin Murphy
0 siblings, 0 replies; 9+ messages in thread
From: Robin Murphy @ 2023-04-20 17:02 UTC (permalink / raw)
To: Ivan T. Ivanov, Mark Rutland
Cc: Catalin Marinas, Will Deacon, Mark Brown, Shawn Guo,
Dong Aisheng, linux-arm-kernel, linux-imx
On 18/04/2023 5:54 pm, Ivan T. Ivanov wrote:
> On 04-17 16:35, Mark Rutland wrote:
>
>>>>> @@ -835,7 +835,8 @@ static inline bool system_supports_bti(void)
>>>>> static inline bool system_supports_tlb_range(void)
>>>>> {
>>>>> return IS_ENABLED(CONFIG_ARM64_TLB_RANGE) &&
>>>>> - cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
>>>>> + cpus_have_const_cap(ARM64_HAS_TLB_RANGE) &&
>>>>> + !cpus_have_const_cap(ARM64_WORKAROUND_NXP_ERR050104);
>>>>> }
>>>>
>>>> It'd be better to handle this in the detection of ARM64_HAS_TLB_RANGE, as we
>>>> have for CNP where has_useable_cnp() checks for ARM64_WORKAROUND_NVIDIA_CARMEL_CNP.
>>>
>>> It's not needed in either place, since neither Cortex-A53 or Cortex-A72
>>> support FEAT_TLBIRANGE, so this could never be true on affected platforms
>>> anyway.
>>
>> Ah, even better -- we can just drop it.
>
> Ok.
>
>>
>>> Tangentially, I understand this platform has an SMMU[1], so I'd say it would
>>> also be worth checking what SMMU_IDR0.BTM reports. With any luck it might be
>>> 0, but if it's 1 then strictly it would want to be overridden as part of a
>>> complete workaround as well. That wouldn't be a practical issue right now,
>>> not least since the current Linux driver doesn't even use BTM, but it's
>>> something which could need to be borne in mind in future.
>>
>> Absolutely.
>
> I don't completely understand implication of this, but for SMMU inside
> iMX8QM report that "Broadcast TLB maintenance is supported"
Aha, in fact it seems we might be OK. I double-checked and it turns out
that thanks to an MMU-500 erratum, we can't necessarily believe IDR0.BTM
anyway. Thus anyone who adds DVM support to an SMMUv2 driver is going to
need to implement some new firmware property or platform detection, at
which point the chances of it getting silently enabled for i.MX8 (if
indeed BTM isn't already a lie there) seem sufficiently remote that I'd
feel fairly comfortable not doing anything explicit for now.
(The case of concern wouldn't be so much the expected use of DVM to
share CPU pagetables with the SMMU, which in principle the regular CPU
workaround should already cover, but more anyone trying to play clever
tricks using DVM and CPU instructions to maintain private SMMU contexts
rather than register-based commands.)
Thanks,
Robin.
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^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-04-20 17:03 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-04-12 12:55 [PATCH] arm64: errata: Add NXP iMX8QM workaround for A53 Cache coherency issue Ivan T. Ivanov
2023-04-13 11:19 ` Mark Rutland
2023-04-14 11:36 ` Robin Murphy
2023-04-17 15:35 ` Mark Rutland
2023-04-18 16:54 ` Ivan T. Ivanov
2023-04-20 17:02 ` Robin Murphy
2023-04-18 13:25 ` Ivan T. Ivanov
2023-04-17 3:07 ` Peng Fan
2023-04-17 14:48 ` Frank Li
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