With ARMv9.5, an implementation supporting Nested Virtualization
is allowed to only support NV2, and to avoid supporting the old
(and useless) ARMv8.3 variant.
This is indicated by ID_AA64MMFR2_EL1.NV being 0 (as if NV wasn't
implemented) and ID_AA64MMDR4_EL1.NV_frac being 1 (indicating that
NV2 is actually supported).
Given that KVM only deals with NV2 and refuses to use the old NV,
detecting NV2 or NV_frac is what we need to enable it.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/kernel/cpufeature.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4eb7c6698ae43..94605e91f0e5f 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -497,6 +497,7 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr3[] = {
static const struct arm64_ftr_bits ftr_id_aa64mmfr4[] = {
S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR4_EL1_E2H0_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR4_EL1_NV_frac_SHIFT, 4, 0),
ARM64_FTR_END,
};
@@ -2162,7 +2163,7 @@ static bool has_nested_virt_support(const struct arm64_cpu_capabilities *cap,
if (kvm_get_mode() != KVM_MODE_NV)
return false;
- if (!has_cpuid_feature(cap, scope)) {
+ if (!cpucap_multi_entry_cap_matches(cap, scope)) {
pr_warn("unavailable: %s\n", cap->desc);
return false;
}
@@ -2519,7 +2520,17 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.capability = ARM64_HAS_NESTED_VIRT,
.type = ARM64_CPUCAP_SYSTEM_FEATURE,
.matches = has_nested_virt_support,
- ARM64_CPUID_FIELDS(ID_AA64MMFR2_EL1, NV, NV2)
+ .match_list = (const struct arm64_cpu_capabilities []){
+ {
+ .matches = has_cpuid_feature,
+ ARM64_CPUID_FIELDS(ID_AA64MMFR2_EL1, NV, NV2)
+ },
+ {
+ .matches = has_cpuid_feature,
+ ARM64_CPUID_FIELDS(ID_AA64MMFR4_EL1, NV_frac, NV2_ONLY)
+ },
+ { /* Sentinel */ }
+ },
},
{
.capability = ARM64_HAS_32BIT_EL0_DO_NOT_USE,
--
2.39.2
