Right now we do not allow any write in mvendorid/marchid/mimpid if the vcpu already started, preventing these regs to be changed. However, if userspace doesn't change them, an alternative is to consider the reg write a no-op and avoid erroring out altogether. Userpace can then be oblivious about KVM internals if no changes were intended in the first place. Allow the same form of 'lazy writing' that registers such as zicbom/zicboz_block_size supports: avoid erroring out if userspace makes no changes in mvendorid/marchid/mimpid during reg write. Signed-off-by: Daniel Henrique Barboza <dbarboza@xxxxxxxxxxxxxxxx> --- arch/riscv/kvm/vcpu_onereg.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c index e752e2dca8ed..818900f30859 100644 --- a/arch/riscv/kvm/vcpu_onereg.c +++ b/arch/riscv/kvm/vcpu_onereg.c @@ -235,18 +235,24 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu, return -EINVAL; break; case KVM_REG_RISCV_CONFIG_REG(mvendorid): + if (reg_val == vcpu->arch.mvendorid) + break; if (!vcpu->arch.ran_atleast_once) vcpu->arch.mvendorid = reg_val; else return -EBUSY; break; case KVM_REG_RISCV_CONFIG_REG(marchid): + if (reg_val == vcpu->arch.marchid) + break; if (!vcpu->arch.ran_atleast_once) vcpu->arch.marchid = reg_val; else return -EBUSY; break; case KVM_REG_RISCV_CONFIG_REG(mimpid): + if (reg_val == vcpu->arch.mimpid) + break; if (!vcpu->arch.ran_atleast_once) vcpu->arch.mimpid = reg_val; else -- 2.41.0
