[PATCHv2] arm64/kvm: Prohibit guest LOR accesses

[Christoffer Dall]

On Tue, Feb 13, 2018 at 01:39:23PM +0000, Mark Rutland wrote:
> We don't currently limit guest accesses to the LOR registers, which we
> neither virtualize nor context-switch. As such, guests are provided with
> unusable information/controls, and are not isolated from each other (or
> the host).
> 
> To prevent these issues, we can trap register accesses and present the
> illusion LORegions are unssupported by the CPU. To do this, we mask
> ID_AA64MMFR1.LO, and set HCR_EL2.TLOR to trap accesses to the following
> registers:
> 
> * LORC_EL1
> * LOREA_EL1
> * LORID_EL1
> * LORN_EL1
> * LORSA_EL1
> 
> ... when trapped, we inject an UNDEFINED exception to EL1, simulating
> their non-existence.
> 
> As noted in D7.2.67, when no LORegions are implemented, LoadLOAcquire
> and StoreLORelease must behave as LoadAcquire and StoreRelease
> respectively. We can ensure this by clearing LORC_EL1.EN when a CPU's
> EL2 is first initialized, as the host kernel will not modify this.
> 
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Vladimir Murzin <vladimir.murzin at arm.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Christoffer Dall <christoffer.dall at linaro.org>
> Cc: Marc Zyngier <marc.zyngier at arm.com>
> Cc: Will Deacon <will.deacon at arm.com>
> Cc: kvmarm at lists.cs.columbia.edu

Applied, thanks.
-Christoffer