Messages in this thread | | | Subject | Re: [PATCH v3 1/7] sysfs/cpu: Allow individual architectures to select vulnerabilities | From | Jeremy Linton <> | Date | Fri, 18 Jan 2019 10:31:00 -0600 |
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On 01/18/2019 09:46 AM, Greg KH wrote: > On Mon, Jan 14, 2019 at 10:02:21AM +0000, Suzuki K Poulose wrote: >> >> >> On 09/01/2019 23:55, Jeremy Linton wrote: >>> As suggested on the list, https://lkml.org/lkml/2019/1/4/282, there are >>> a number of cases where its useful for a system to avoid exporting a >>> sysfs entry for a given vulnerability. This set adds an architecture >>> specific callback which returns the bitmap of vulnerabilities the >>> architecture would like to advertise. >>> >>> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >>> Cc: Rafael J. Wysocki <rafael@kernel.org> >>> Cc: Thomas Gleixner <tglx@linutronix.de> >>> Cc: Josh Poimboeuf <jpoimboe@redhat.com> >>> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>> Cc: Ingo Molnar <mingo@kernel.org> >>> Cc: Waiman Long <longman@redhat.com> >>> Cc: Andi Kleen <ak@linux.intel.com> >>> Cc: Jiri Kosina <jkosina@suse.cz> >>> --- >>> drivers/base/cpu.c | 19 +++++++++++++++++++ >>> include/linux/cpu.h | 7 +++++++ >>> 2 files changed, 26 insertions(+) >>> >>> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c >>> index eb9443d5bae1..35f6dfb24cd6 100644 >>> --- a/drivers/base/cpu.c >>> +++ b/drivers/base/cpu.c >>> @@ -561,6 +561,11 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = { >>> NULL >>> }; >>> +uint __weak arch_supported_vuln_attr_fields(void) >>> +{ >>> + return VULN_MELTDOWN|VULN_SPECTREV1|VULN_SPECTREV2|VULN_SSB|VULN_L1TF; >>> +} >>> + >>> static const struct attribute_group cpu_root_vulnerabilities_group = { >>> .name = "vulnerabilities", >>> .attrs = cpu_root_vulnerabilities_attrs, >>> @@ -568,6 +573,20 @@ static const struct attribute_group cpu_root_vulnerabilities_group = { >>> static void __init cpu_register_vulnerabilities(void) >>> { >>> + int fld; >>> + int max_fields = ARRAY_SIZE(cpu_root_vulnerabilities_attrs) - 1; >>> + struct attribute **hd = cpu_root_vulnerabilities_attrs; >>> + uint enabled_fields = arch_supported_vuln_attr_fields(); >>> + >>> + /* only enable entries requested by the arch code */ >>> + for (fld = 0; fld < max_fields; fld++) { >>> + if (enabled_fields & 1 << fld) { >>> + *hd = cpu_root_vulnerabilities_attrs[fld]; >>> + hd++; >>> + } >>> + } >>> + *hd = NULL; >>> + >> >> nit: Could we use "is_visible" callback in the attribute group to check this >> dynamically ? > > You should, that is what it is there for.
Yes, its a good suggestion. OTOH, I think the plan is to drop this functionality all together by removing the ability to build kernels without the vulnerability checking/processor white lists. That will simplify some of the #ifdef'ing going on as well.
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