From d8b369c4e31430a4746571bcae45a98933827232 Mon Sep 17 00:00:00 2001 From: David Brazdil Date: Wed, 2 Dec 2020 18:40:57 +0000 Subject: [PATCH] KVM: arm64: Add kvm-arm.mode early kernel parameter Add an early parameter that allows users to select the mode of operation for KVM/arm64. For now, the only supported value is "protected". By passing this flag users opt into the hypervisor placing additional restrictions on the host kernel. These allow the hypervisor to spawn guests whose state is kept private from the host. Restrictions will include stage-2 address translation to prevent host from accessing guest memory, filtering its SMC calls, etc. Without this parameter, the default behaviour remains selecting VHE/nVHE based on hardware support and CONFIG_ARM64_VHE. Signed-off-by: David Brazdil Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20201202184122.26046-2-dbrazdil@google.com --- Documentation/admin-guide/kernel-parameters.txt | 10 ++++++++++ arch/arm64/include/asm/kvm_host.h | 9 +++++++++ arch/arm64/kvm/arm.c | 16 ++++++++++++++++ 3 files changed, 35 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 526d65d8573a4..ee9f137763888 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2259,6 +2259,16 @@ for all guests. Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. + kvm-arm.mode= + [KVM,ARM] Select one of KVM/arm64's modes of operation. + + protected: nVHE-based mode with support for guests whose + state is kept private from the host. + Not valid if the kernel is running in EL2. + + Defaults to VHE/nVHE based on hardware support and + the value of CONFIG_ARM64_VHE. + kvm-arm.vgic_v3_group0_trap= [KVM,ARM] Trap guest accesses to GICv3 group-0 system registers diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 781d029b8aa85..820954ad24776 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -50,6 +50,15 @@ #define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \ KVM_DIRTY_LOG_INITIALLY_SET) +/* + * Mode of operation configurable with kvm-arm.mode early param. + * See Documentation/admin-guide/kernel-parameters.txt for more information. + */ +enum kvm_mode { + KVM_MODE_DEFAULT, + KVM_MODE_PROTECTED, +}; + DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use); extern unsigned int kvm_sve_max_vl; diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 5750ec34960e9..5db90680742c2 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -46,6 +46,8 @@ __asm__(".arch_extension virt"); #endif +static enum kvm_mode kvm_mode = KVM_MODE_DEFAULT; + DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector); static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page); @@ -1790,6 +1792,20 @@ void kvm_arch_exit(void) kvm_perf_teardown(); } +static int __init early_kvm_mode_cfg(char *arg) +{ + if (!arg) + return -EINVAL; + + if (strcmp(arg, "protected") == 0) { + kvm_mode = KVM_MODE_PROTECTED; + return 0; + } + + return -EINVAL; +} +early_param("kvm-arm.mode", early_kvm_mode_cfg); + static int arm_init(void) { int rc = kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE); -- 2.39.5