[PATCH 03/59] arm64: Add ARM64_HAS_NESTED_VIRT cpufeature

Marc Zyngier
2019-06-21T09:39:23Z

From: Jintack Lim <jintack.lim@linaro.org>

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@linaro.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
.../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 138f6664b2e2..202bb2115d83 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2046,6 +2046,10 @@
[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 33401ebc187c..faa13c1f1f65 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -63,7 +63,8 @@
#define ARM64_HAS_IRQ_PRIO_MASKING 42
#define ARM64_HAS_DCPODP 43
#define ARM64_WORKAROUND_1463225 44
+#define ARM64_HAS_NESTED_VIRT 45

-#define ARM64_NCAPS 45
+#define ARM64_NCAPS 46

#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 434cf53d527b..f3ca7e4796ab 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -693,6 +693,7 @@
/* id_aa64mmfr2 */
#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 80babf451519..2f8e7d4e8e45 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -224,6 +224,7 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr1[] = {
static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
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),
@@ -1161,6 +1162,21 @@ 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)
@@ -1331,6 +1347,16 @@ 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