With FEAT_IDST, unimplemented system registers must be reported using EC=0x18 at the closest handling EL, rather than with an UNDEF. Most system registers are always implemented thanks to their dependency on FEAT_AA64, except for a set of (currently) three registers: GMID_EL1 (depending on MTE2), CCSIDR2_EL1 (depending on FEAT_CCIDX), and SMIDR_EL1 (depending on SME). For these three registers, report their trap as EC=0x18 if they end-up trapping into KVM and that FEAT_IDST is not implemented in the guest. Otherwise, just make them UNDEF. Signed-off-by: Marc Zyngier --- arch/arm64/kvm/sys_regs.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 40f32b017f107..992137822dcf9 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -82,6 +82,16 @@ static bool write_to_read_only(struct kvm_vcpu *vcpu, "sys_reg write to read-only register"); } +static bool idst_access(struct kvm_vcpu *vcpu, struct sys_reg_params *p, + const struct sys_reg_desc *r) +{ + if (kvm_has_feat_enum(vcpu->kvm, ID_AA64MMFR2_EL1, IDS, 0x0)) + return undef_access(vcpu, p, r); + + kvm_inject_sync(vcpu, kvm_vcpu_get_esr(vcpu)); + return false; +} + enum sr_loc_attr { SR_LOC_MEMORY = 0, /* Register definitely in memory */ SR_LOC_LOADED = BIT(0), /* Register on CPU, unless it cannot */ @@ -3396,9 +3406,9 @@ static const struct sys_reg_desc sys_reg_descs[] = { { SYS_DESC(SYS_CCSIDR_EL1), access_ccsidr }, { SYS_DESC(SYS_CLIDR_EL1), access_clidr, reset_clidr, CLIDR_EL1, .set_user = set_clidr, .val = ~CLIDR_EL1_RES0 }, - { SYS_DESC(SYS_CCSIDR2_EL1), undef_access }, - { SYS_DESC(SYS_GMID_EL1), undef_access }, - { SYS_DESC(SYS_SMIDR_EL1), undef_access }, + { SYS_DESC(SYS_CCSIDR2_EL1), idst_access }, + { SYS_DESC(SYS_GMID_EL1), idst_access }, + { SYS_DESC(SYS_SMIDR_EL1), idst_access }, IMPLEMENTATION_ID(AIDR_EL1, GENMASK_ULL(63, 0)), { SYS_DESC(SYS_CSSELR_EL1), access_csselr, reset_unknown, CSSELR_EL1 }, ID_FILTERED(CTR_EL0, ctr_el0, -- 2.47.3