KVM: arm64: Synchronize SMEN on vcpu schedule out

If we have VHE and need to reenable SME for host in
kvm_arch_vcpu_put_fp, CPACR.SMEN is modified from 0 to 1. Trap
control for reading SVCR is modified from enable to disable.
Synchronization is needed before reading SVCR later in
fpsimd_save, or it may cause sync exception which can not be
handled by host.

Cc: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Nianyao Tang <tangnianyao@huawei.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221220105024.13484-1-dongbo4@huawei.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 02dd7e9ebd391fe13e7b367c74b707812534a609..f5799f571317238119f98b0c11c4ce49a6a20976 100644 (file)
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -184,6 +184,7 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
                        sysreg_clear_set(CPACR_EL1,
                                         CPACR_EL1_SMEN_EL0EN,
                                         CPACR_EL1_SMEN_EL1EN);
+               isb();
        }
 
        if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {