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KVM: arm64: pkvm: Report optional ID register traps with a 0x18 syndrome

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With FEAT_IDST, unimplemented system registers in the feature ID space
must be reported using EC=0x18 at the closest handling EL, rather than
with an UNDEF.

Most of these 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 implemented in the guest.
Otherwise, just make them UNDEF.

Link: https://patch.msgid.link/20260108173233.2911955-9-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2026-01-08 17:32:32 +00:00
parent e5d40a5a97
commit 592dc2c020
1 changed files with 15 additions and 0 deletions
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15
arch/arm64/kvm/hyp/nvhe/sys_regs.c
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@ -347,6 +347,18 @@ static bool pvm_gic_read_sre(struct kvm_vcpu *vcpu,
return true;
}
static bool pvm_idst_access(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
if (kvm_has_feat(vcpu->kvm, ID_AA64MMFR2_EL1, IDS, IMP))
inject_sync64(vcpu, kvm_vcpu_get_esr(vcpu));
else
inject_undef64(vcpu);
return false;
}
/* Mark the specified system register as an AArch32 feature id register. */
#define AARCH32(REG) { SYS_DESC(REG), .access = pvm_access_id_aarch32 }
@ -477,6 +489,9 @@ static const struct sys_reg_desc pvm_sys_reg_descs[] = {
HOST_HANDLED(SYS_CCSIDR_EL1),
HOST_HANDLED(SYS_CLIDR_EL1),
{ SYS_DESC(SYS_CCSIDR2_EL1), .access = pvm_idst_access },
{ SYS_DESC(SYS_GMID_EL1), .access = pvm_idst_access },
{ SYS_DESC(SYS_SMIDR_EL1), .access = pvm_idst_access },
HOST_HANDLED(SYS_AIDR_EL1),
HOST_HANDLED(SYS_CSSELR_EL1),
HOST_HANDLED(SYS_CTR_EL0),