[PATCH v1 0/2] KVM: arm: Refuse to enable KVM on systems with SME but not FGT

[Richard Henderson]

On 10/28/22 06:52, Mark Brown wrote:
> The architecture requires that any system which implements SME also has
> fine grained traps since SME is a v9.2 feature, meaning that v8.7 must be
> implemented, and FGT is mandatory from v8.6. SME relies on fine grained
> traps to control access to SMPRI_EL1 and in nVHE mode to TPIDR2_EL0,
> without traps SMPRI_EL1.Priority and TPIDR2_EL0 can be used as side
> channels.
> 
> This series adds support for detecting FGT and refuses to allow KVM to
> be used in architecturally invalid configurations which have SME but not
> FGT, without detection the issue presents as faults due to EL2
> attempting to access the FGT registers which isn't obvious to users.
> Currently fine grained traps are only used in nVHE but but a series
> "arm64/sme: Fix SMPRI_EL1 traps for KVM guests" sent along with this
> will add usage for VHE mode too making the issue more pressing.

Series:
Reviewed-by: Richard Henderson <richard.henderson at linaro.org>


r~