[PATCH v2 07/10] KVM: arm64: Expose the WFXT feature to guests

Marc Zyngier
2022-04-19T18:34:21Z

Plumb in the capability, and expose WFxT to guests when available.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kernel/cpufeature.c | 12 ++++++++++++
arch/arm64/kvm/sys_regs.c | 2 ++
2 files changed, 14 insertions(+)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index d72c4b4d389c..db6d9ab685e5 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -237,6 +237,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar2[] = {
ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_GPA3_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_RPRES_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_WFXT_SHIFT, 4, 0),
ARM64_FTR_END,
};

@@ -2442,6 +2443,17 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.matches = has_cpuid_feature,
.min_field_value = 1,
},
+ {
+ .desc = "WFx with timeout",
+ .capability = ARM64_HAS_WFXT,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .sys_reg = SYS_ID_AA64ISAR2_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64ISAR2_WFXT_SHIFT,
+ .field_width = 4,
+ .matches = has_cpuid_feature,
+ .min_field_value = ID_AA64ISAR2_WFXT_SUPPORTED,
+ },
{},
};

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 7b45c040cc27..cc9a77546cc0 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1144,6 +1144,8 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
if (!vcpu_has_ptrauth(vcpu))
val &= ~(ARM64_FEATURE_MASK(ID_AA64ISAR2_APA3) |
ARM64_FEATURE_MASK(ID_AA64ISAR2_GPA3));
+ if (!cpus_have_final_cap(ARM64_HAS_WFXT))
+ val &= ~ARM64_FEATURE_MASK(ID_AA64ISAR2_WFXT);
break;
case SYS_ID_AA64DFR0_EL1:
/* Limit debug to ARMv8.0 */
--
2.34.1