From: Ard Biesheuvel ardb@kernel.org
[ Upstream commit 0609e200246bfd3b7516091c491bec4308349055 ]
Jon reports that the Spectre-BHB init code is filling up the kernel log with spurious notifications about which mitigation has been enabled, every time any CPU comes out of a low power state.
Given that Spectre-BHB mitigations are system wide, only a single mitigation can be enabled, and we already print an error if two types of CPUs coexist in a single system that require different Spectre-BHB mitigations.
This means that the pr_info() that describes the selected mitigation does not need to be emitted for each CPU anyway, and so we can simply emit it only once.
In order to clarify the above in the log message, update it to describe that the selected mitigation will be enabled on all CPUs, including ones that are unaffected. If another CPU comes up later that is affected and requires a different mitigation, we report an error as before.
Fixes: b9baf5c8c5c3 ("ARM: Spectre-BHB workaround") Tested-by: Jon Hunter jonathanh@nvidia.com Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/mm/proc-v7-bugs.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm/mm/proc-v7-bugs.c b/arch/arm/mm/proc-v7-bugs.c index f2c8ff0683fd..b09c54499f95 100644 --- a/arch/arm/mm/proc-v7-bugs.c +++ b/arch/arm/mm/proc-v7-bugs.c @@ -221,10 +221,10 @@ static int spectre_bhb_install_workaround(int method) return SPECTRE_VULNERABLE;
spectre_bhb_method = method; - }
- pr_info("CPU%u: Spectre BHB: using %s workaround\n", - smp_processor_id(), spectre_bhb_method_name(method)); + pr_info("CPU%u: Spectre BHB: enabling %s workaround for all CPUs\n", + smp_processor_id(), spectre_bhb_method_name(method)); + }
return SPECTRE_MITIGATED; }