Hi Marc,
On Tue, May 29, 2018 at 01:11:04PM +0100, Marc Zyngier wrote:
> This patch series implements the Linux kernel side of the "Spectre-v4"
> (CVE-2018-3639) mitigation known as "Speculative Store Bypass Disable"
> (SSBD).
>
> More information can be found at:
>
>
This small series makes use of features recently introduced in the
ARMv8 architecture to relax the cache maintenance operations on CPUs
that implement these features.
FWB is the most important one. It allows stage-2 to enforce the
cacheability of memory, no matter what the guest says. It also
Up to ARMv8.3, the combinaison of Stage-1 and Stage-2 attributes
results in the strongest attribute of the two stages. This means
that the hypervisor has to perform quite a lot of cache maintenance
just in case the guest has some non-cacheable mappings around.
ARMv8.4 solves this problem by
Set/Way handling is one of the ugliest corners of KVM. We shouldn't
have to handle that, but better safe than sorry.
Thankfully, FWB fixes this for us by not requiering any maintenance
whatsoever, which means we don't have to emulate S/W CMOs, and don't
have to track VM ops either.
We still have
The arm and arm64 KVM page tables accessors are pointlessly different
between the two architectures, and likely both wrong one way or another:
arm64 lacks a dsb(), and arm doesn't use WRITE_ONCE.
Let's unify them.
Signed-off-by: Marc Zyngier
---
arch/arm/include/asm/kvm_mmu.h | 12
The {pmd,pud,pgd}_populate accessors usage in the kernel have always
been a bit weird in KVM. We don't have a struct mm to pass (and
neither does the kernel most of the time, but still...), and
the 32bit code has all kind of cache maintenance that doesn't make
sense on ARMv7+ when MP extensions
