From: Jintack Lim <jintack.lim@xxxxxxxxxx>
Add a new ARM64_HAS_NESTED_VIRT feature to indicate that the
CPU has the ARMv8.3 nested virtualization capability.
This will be used to support nested virtualization in KVM.
Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx>
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
.../admin-guide/kernel-parameters.txt | 4 +++
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/kernel/cpufeature.c | 26 +++++++++++++++++++
4 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index dbc22d684627..cb61ace641f1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2151,6 +2151,10 @@
[KVM,ARM] Allow use of GICv4 for direct injection of
LPIs.
+ kvm-arm.nested=
+ [KVM,ARM] Allow nested virtualization in KVM/ARM.
+ Default is 0 (disabled)
+
kvm-intel.ept= [KVM,Intel] Disable extended page tables
(virtualized MMU) support on capable Intel chips.
Default is 1 (enabled)
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 865e0253fc1e..21f0067d8d40 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -58,7 +58,8 @@
#define ARM64_WORKAROUND_SPECULATIVE_AT_NVHE 48
#define ARM64_HAS_E0PD 49
#define ARM64_HAS_RNG 50
+#define ARM64_HAS_NESTED_VIRT 51
-#define ARM64_NCAPS 51
+#define ARM64_NCAPS 52
#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index b91570ff9db1..00b283d6d31a 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -687,6 +687,7 @@
#define ID_AA64MMFR2_E0PD_SHIFT 60
#define ID_AA64MMFR2_FWB_SHIFT 40
#define ID_AA64MMFR2_AT_SHIFT 32
+#define ID_AA64MMFR2_NV_SHIFT 24
#define ID_AA64MMFR2_LVA_SHIFT 16
#define ID_AA64MMFR2_IESB_SHIFT 12
#define ID_AA64MMFR2_LSM_SHIFT 8
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 0b6715625cf6..f0e58450eb16 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -243,6 +243,7 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_E0PD_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_FWB_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_AT_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_NV_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LVA_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_IESB_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LSM_SHIFT, 4, 0),
@@ -1241,6 +1242,21 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
if (!alternative_is_applied(ARM64_HAS_VIRT_HOST_EXTN))
write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
}
+
+static bool nested_param;
+static bool has_nested_virt_support(const struct arm64_cpu_capabilities *cap,
+ int scope)
+{
+ return has_cpuid_feature(cap, scope) &&
+ nested_param;
+}
+
+static int __init kvmarm_nested_cfg(char *buf)
+{
+ return strtobool(buf, &nested_param);
+}
+
+early_param("kvm-arm.nested", kvmarm_nested_cfg);
#endif
static void cpu_has_fwb(const struct arm64_cpu_capabilities *__unused)
@@ -1419,6 +1435,16 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.matches = runs_at_el2,
.cpu_enable = cpu_copy_el2regs,
},
+ {
+ .desc = "Nested Virtualization Support",
+ .capability = ARM64_HAS_NESTED_VIRT,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_nested_virt_support,
+ .sys_reg = SYS_ID_AA64MMFR2_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64MMFR2_NV_SHIFT,
+ .min_field_value = 1,
+ },
#endif /* CONFIG_ARM64_VHE */
{
.desc = "32-bit EL0 Support",
--
2.20.1
