On Thu, Feb 06, 2025 at 02:10:57PM +0000, Mark Rutland wrote: > When KVM is in VHE mode, the host kernel tries to save and restore the > configuration of CPACR_EL1.ZEN (i.e. CPTR_EL2.ZEN when HCR_EL2.E2H=1) > across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the > configuration may be clobbered by hyp when running a vCPU. This logic is > currently redundant. > > The VHE hyp code unconditionally configures CPTR_EL2.ZEN to 0b01 when > returning to the host, permitting host kernel usage of SVE. > > Now that the host eagerly saves and unbinds its own FPSIMD/SVE/SME > state, there's no need to save/restore the state of the EL0 SVE trap. > The kernel can safely save/restore state without trapping, as described > above, and will restore userspace state (including trap controls) before > returning to userspace. > > Remove the redundant logic. > > Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> > Reviewed-by: Mark Brown <broonie@xxxxxxxxxx> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > Cc: Fuad Tabba <tabba@xxxxxxxxxx> > Cc: Marc Zyngier <maz@xxxxxxxxxx> > Cc: Mark Brown <broonie@xxxxxxxxxx> > Cc: Oliver Upton <oliver.upton@xxxxxxxxx> > Cc: Will Deacon <will@xxxxxxxxxx> > --- > arch/arm64/include/asm/kvm_host.h | 1 - > arch/arm64/kvm/fpsimd.c | 16 ---------------- > 2 files changed, 17 deletions(-) Acked-by: Will Deacon <will@xxxxxxxxxx> Will
