This allows KVM users to enable the workaround until a mechanism
is implemented to automatically communicate this information.
Signed-off-by: Scott Wood <oss@xxxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 9 +++++++++
drivers/clocksource/arm_arch_timer.c | 20 +++++++++++++++++++-
2 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a4f4d69..25037de 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -698,6 +698,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
loops can be debugged more effectively on production
systems.
+ clocksource.arm_arch_timer.fsl-a008585=
+ [ARM64]
+ Format: <bool>
+ Enable/disable the workaround of Freescale/NXP
+ erratum A-008585. This can be useful for KVM
+ guests, if the guest device tree doesn't show the
+ erratum. If unspecified, the workaround is
+ enabled based on the device tree.
+
clearcpuid=BITNUM [X86]
Disable CPUID feature X for the kernel. See
arch/x86/include/asm/cpufeatures.h for the valid bit
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 36d4ee1..e70e530 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -98,6 +98,22 @@ early_param("clocksource.arm_arch_timer.evtstrm", early_evtstrm_cfg);
DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled);
EXPORT_SYMBOL_GPL(arch_timer_read_ool_enabled);
+static int fsl_a008585_enable = -1;
+
+static int __init early_fsl_a008585_cfg(char *buf)
+{
+ int ret;
+ bool val;
+
+ ret = strtobool(buf, &val);
+ if (ret)
+ return ret;
+
+ fsl_a008585_enable = val;
+ return 0;
+}
+early_param("clocksource.arm_arch_timer.fsl-a008585", early_fsl_a008585_cfg);
+
/*
* __always_inline is used to ensure that func() is not an actual function
* pointer, which would result in the register accesses potentially being too
@@ -895,7 +911,9 @@ static int __init arch_timer_of_init(struct device_node *np)
arch_timer_c3stop = !of_property_read_bool(np, "always-on");
#ifdef CONFIG_FSL_ERRATUM_A008585
- if (of_property_read_bool(np, "fsl,erratum-a008585"))
+ if (fsl_a008585_enable < 0)
+ fsl_a008585_enable = of_property_read_bool(np, "fsl,erratum-a008585");
+ if (fsl_a008585_enable)
static_branch_enable(&arch_timer_read_ool_enabled);
#endif
--
2.7.4
--
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