From: Jintack Lim <[email protected]> Add a new ARM64_HAS_NESTED_VIRT feature to indicate that the CPU has the ARMv8.3 nested virtualization capability, together with the 'kvm-arm.mode=nested' command line option.
This will be used to support nested virtualization in KVM. Signed-off-by: Jintack Lim <[email protected]> Signed-off-by: Andre Przywara <[email protected]> Signed-off-by: Christoffer Dall <[email protected]> [maz: moved the command-line option to kvm-arm.mode] Signed-off-by: Marc Zyngier <[email protected]> --- .../admin-guide/kernel-parameters.txt | 7 +++++- arch/arm64/include/asm/kvm_host.h | 5 ++++ arch/arm64/kernel/cpufeature.c | 24 +++++++++++++++++++ arch/arm64/kvm/arm.c | 5 ++++ arch/arm64/tools/cpucaps | 1 + 5 files changed, 41 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f5a27f067db9..466d8fdbaee2 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2391,9 +2391,14 @@ state is kept private from the host. Not valid if the kernel is running in EL2. + nested: VHE-based mode with support for nested + virtualization. Requires at least ARMv8.3 + hardware. + Defaults to VHE/nVHE based on hardware support. Setting mode to "protected" will disable kexec and hibernation - for the host. + for the host. "nested" is experimental and should be + used with extreme caution. kvm-arm.vgic_v3_group0_trap= [KVM,ARM] Trap guest accesses to GICv3 group-0 diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 5bc01e62c08a..115e0e2caf9a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -57,9 +57,14 @@ enum kvm_mode { KVM_MODE_DEFAULT, KVM_MODE_PROTECTED, + KVM_MODE_NV, KVM_MODE_NONE, }; +#ifdef CONFIG_KVM enum kvm_mode kvm_get_mode(void); +#else +static inline enum kvm_mode kvm_get_mode(void) { return KVM_MODE_NONE; }; +#endif DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use); diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index a46ab3b1c4d5..2fa39ce108d0 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1772,6 +1772,20 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused) write_sysreg(read_sysreg(tpidr_el1), tpidr_el2); } +static bool has_nested_virt_support(const struct arm64_cpu_capabilities *cap, + int scope) +{ + if (kvm_get_mode() != KVM_MODE_NV) + return false; + + if (!has_cpuid_feature(cap, scope)) { + pr_warn("unavailable: %s\n", cap->desc); + return false; + } + + return true; +} + static void cpu_has_fwb(const struct arm64_cpu_capabilities *__unused) { u64 val = read_sysreg_s(SYS_CLIDR_EL1); @@ -2005,6 +2019,16 @@ 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, + }, { .capability = ARM64_HAS_32BIT_EL0_DO_NOT_USE, .type = ARM64_CPUCAP_SYSTEM_FEATURE, diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index a4a0063df456..06ca11e90482 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -2209,6 +2209,11 @@ static int __init early_kvm_mode_cfg(char *arg) return 0; } + if (strcmp(arg, "nested") == 0 && !WARN_ON(!is_kernel_in_hyp_mode())) { + kvm_mode = KVM_MODE_NV; + return 0; + } + if (strcmp(arg, "none") == 0) { kvm_mode = KVM_MODE_NONE; return 0; diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 870c39537dd0..a49864b56a07 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -26,6 +26,7 @@ HAS_GENERIC_AUTH_IMP_DEF HAS_IRQ_PRIO_MASKING HAS_LDAPR HAS_LSE_ATOMICS +HAS_NESTED_VIRT HAS_NO_FPSIMD HAS_NO_HW_PREFETCH HAS_PAN -- 2.30.2 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
