On 5/15/20 12:36 AM, Thorsten Schubert wrote:
Your linked document [1] describes in detail how to mitigate and also
lists the associated performance degradation.
LWN also provides a good summary for L1TF [2].
Yeah, I am reading up on that. But I am not a kernel developer or a
kernel administrator, hence I was hoping to get some info from here.
On my private machines with older CPUs, I tend to use mitigations=off
to disable all CPU mitigation techniques introduced since Meltdown in
order to gain some performance back.
I see. This is really annoying. I hate having to sacrifice speed for
security. My PC is slow as it is.
I/O and context switches in
general are really slow with enabled mitigations on Sandy and Ivy
Bridge, so I am willing to take some risks on these platforms, which
is of course not recommended and possibly a really bad idea:-)
Exactly what I am afraid of. I run a lot of VMs to test out untrusted
software and practice for CTFs. Basically what this bug does is break
sanboxing completely AFAIK.
$ grep ./sys/devices/system/cpu/vulnerabilities/*
/sys/devices/system/cpu/vulnerabilities/itlb_multihit:KVM: Vulnerable
/sys/devices/system/cpu/vulnerabilities/l1tf:Mitigation: PTE
Inversion; VMX: vulnerable
/sys/devices/system/cpu/vulnerabilities/mds:Vulnerable; SMT vulnerable
/sys/devices/system/cpu/vulnerabilities/meltdown:Vulnerable
/sys/devices/system/cpu/vulnerabilities/spec_store_bypass:Vulnerable
/sys/devices/system/cpu/vulnerabilities/spectre_v1:Vulnerable: __user
pointer sanitization and usercopy barriers only; no swapgs barriers
/sys/devices/system/cpu/vulnerabilities/spectre_v2:Vulnerable, IBPB:
disabled, STIBP: disabled
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort:Not affected
I am just curious, but how many of these vulnerabilities do you find on
AMD CPUs ?
--
Regards,
Sreyan
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