| Message ID | 20210409152154.198566-3-alexandru.elisei@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Hide SPE from guests | expand |
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 402cd11aa4fc..61ee9bfb8826 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1063,6 +1063,8 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, val = cpuid_feature_cap_perfmon_field(val, ID_AA64DFR0_PMUVER_SHIFT, kvm_vcpu_has_pmu(vcpu) ? ID_AA64DFR0_PMUVER_8_4 : 0); + /* Hide SPE from guests */ + val &= ~FEATURE(ID_AA64DFR0_PMSVER); break; case SYS_ID_DFR0_EL1: /* Limit guests to PMUv3 for ARMv8.4 */
Even though KVM sets up MDCR_EL2 to trap accesses to the SPE buffer and sampling control registers and to inject an undefined exception, the presence of FEAT_SPE is still advertised in the ID_AA64DFR0_EL1 register, if the hardware supports it. Getting an undefined exception when accessing a register usually happens for a hardware feature which is not implemented, and indeed this is how PMU emulation is handled when the virtual machine has been created without the KVM_ARM_VCPU_PMU_V3 feature. Let's be consistent and never advertise FEAT_SPE, because KVM doesn't have support for emulating it yet. Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> --- arch/arm64/kvm/sys_regs.c | 2 ++ 1 file changed, 2 insertions(+)