From f7d03fcbf1f482069e9afac55b17de3bd323b8f6 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Wed, 18 Dec 2024 19:40:50 +0000 Subject: [PATCH] KVM: arm64: Introduce __pkvm_vcpu_{load,put}() Rather than look-up the hyp vCPU on every run hypercall at EL2, introduce a per-CPU 'loaded_hyp_vcpu' tracking variable which is updated by a pair of load/put hypercalls called directly from kvm_arch_vcpu_{load,put}() when pKVM is enabled. Tested-by: Fuad Tabba Reviewed-by: Fuad Tabba Signed-off-by: Quentin Perret Link: https://lore.kernel.org/r/20241218194059.3670226-10-qperret@google.com Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/kvm_asm.h | 2 ++ arch/arm64/kvm/arm.c | 14 ++++++++ arch/arm64/kvm/hyp/include/nvhe/pkvm.h | 7 ++++ arch/arm64/kvm/hyp/nvhe/hyp-main.c | 47 ++++++++++++++++++++------ arch/arm64/kvm/hyp/nvhe/pkvm.c | 29 ++++++++++++++++ arch/arm64/kvm/vgic/vgic-v3.c | 6 ++-- 6 files changed, 93 insertions(+), 12 deletions(-) diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index ca25903443135..89c0fac695516 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -79,6 +79,8 @@ enum __kvm_host_smccc_func { __KVM_HOST_SMCCC_FUNC___pkvm_init_vm, __KVM_HOST_SMCCC_FUNC___pkvm_init_vcpu, __KVM_HOST_SMCCC_FUNC___pkvm_teardown_vm, + __KVM_HOST_SMCCC_FUNC___pkvm_vcpu_load, + __KVM_HOST_SMCCC_FUNC___pkvm_vcpu_put, }; #define DECLARE_KVM_VHE_SYM(sym) extern char sym[] diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index a102c3aebdbc4..55cc62b2f4691 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -619,12 +619,26 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) kvm_arch_vcpu_load_debug_state_flags(vcpu); + if (is_protected_kvm_enabled()) { + kvm_call_hyp_nvhe(__pkvm_vcpu_load, + vcpu->kvm->arch.pkvm.handle, + vcpu->vcpu_idx, vcpu->arch.hcr_el2); + kvm_call_hyp(__vgic_v3_restore_vmcr_aprs, + &vcpu->arch.vgic_cpu.vgic_v3); + } + if (!cpumask_test_cpu(cpu, vcpu->kvm->arch.supported_cpus)) vcpu_set_on_unsupported_cpu(vcpu); } void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) { + if (is_protected_kvm_enabled()) { + kvm_call_hyp(__vgic_v3_save_vmcr_aprs, + &vcpu->arch.vgic_cpu.vgic_v3); + kvm_call_hyp_nvhe(__pkvm_vcpu_put); + } + kvm_arch_vcpu_put_debug_state_flags(vcpu); kvm_arch_vcpu_put_fp(vcpu); if (has_vhe()) diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h index f361d8b91930d..be52c5b15e219 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h +++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h @@ -20,6 +20,12 @@ struct pkvm_hyp_vcpu { /* Backpointer to the host's (untrusted) vCPU instance. */ struct kvm_vcpu *host_vcpu; + + /* + * If this hyp vCPU is loaded, then this is a backpointer to the + * per-cpu pointer tracking us. Otherwise, NULL if not loaded. + */ + struct pkvm_hyp_vcpu **loaded_hyp_vcpu; }; /* @@ -69,6 +75,7 @@ int __pkvm_teardown_vm(pkvm_handle_t handle); struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle, unsigned int vcpu_idx); void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu); +struct pkvm_hyp_vcpu *pkvm_get_loaded_hyp_vcpu(void); struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle); void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 6aa0b13d86e58..95d78db315b3f 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -141,16 +141,46 @@ static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu) host_cpu_if->vgic_lr[i] = hyp_cpu_if->vgic_lr[i]; } +static void handle___pkvm_vcpu_load(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1); + DECLARE_REG(unsigned int, vcpu_idx, host_ctxt, 2); + DECLARE_REG(u64, hcr_el2, host_ctxt, 3); + struct pkvm_hyp_vcpu *hyp_vcpu; + + if (!is_protected_kvm_enabled()) + return; + + hyp_vcpu = pkvm_load_hyp_vcpu(handle, vcpu_idx); + if (!hyp_vcpu) + return; + + if (pkvm_hyp_vcpu_is_protected(hyp_vcpu)) { + /* Propagate WFx trapping flags */ + hyp_vcpu->vcpu.arch.hcr_el2 &= ~(HCR_TWE | HCR_TWI); + hyp_vcpu->vcpu.arch.hcr_el2 |= hcr_el2 & (HCR_TWE | HCR_TWI); + } +} + +static void handle___pkvm_vcpu_put(struct kvm_cpu_context *host_ctxt) +{ + struct pkvm_hyp_vcpu *hyp_vcpu; + + if (!is_protected_kvm_enabled()) + return; + + hyp_vcpu = pkvm_get_loaded_hyp_vcpu(); + if (hyp_vcpu) + pkvm_put_hyp_vcpu(hyp_vcpu); +} + static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt) { DECLARE_REG(struct kvm_vcpu *, host_vcpu, host_ctxt, 1); int ret; - host_vcpu = kern_hyp_va(host_vcpu); - if (unlikely(is_protected_kvm_enabled())) { - struct pkvm_hyp_vcpu *hyp_vcpu; - struct kvm *host_kvm; + struct pkvm_hyp_vcpu *hyp_vcpu = pkvm_get_loaded_hyp_vcpu(); /* * KVM (and pKVM) doesn't support SME guests for now, and @@ -163,9 +193,6 @@ static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt) goto out; } - host_kvm = kern_hyp_va(host_vcpu->kvm); - hyp_vcpu = pkvm_load_hyp_vcpu(host_kvm->arch.pkvm.handle, - host_vcpu->vcpu_idx); if (!hyp_vcpu) { ret = -EINVAL; goto out; @@ -176,12 +203,10 @@ static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt) ret = __kvm_vcpu_run(&hyp_vcpu->vcpu); sync_hyp_vcpu(hyp_vcpu); - pkvm_put_hyp_vcpu(hyp_vcpu); } else { /* The host is fully trusted, run its vCPU directly. */ - ret = __kvm_vcpu_run(host_vcpu); + ret = __kvm_vcpu_run(kern_hyp_va(host_vcpu)); } - out: cpu_reg(host_ctxt, 1) = ret; } @@ -409,6 +434,8 @@ static const hcall_t host_hcall[] = { HANDLE_FUNC(__pkvm_init_vm), HANDLE_FUNC(__pkvm_init_vcpu), HANDLE_FUNC(__pkvm_teardown_vm), + HANDLE_FUNC(__pkvm_vcpu_load), + HANDLE_FUNC(__pkvm_vcpu_put), }; static void handle_host_hcall(struct kvm_cpu_context *host_ctxt) diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index d46a02e24e4aa..496d186efb03b 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -23,6 +23,12 @@ unsigned int kvm_arm_vmid_bits; unsigned int kvm_host_sve_max_vl; +/* + * The currently loaded hyp vCPU for each physical CPU. Used only when + * protected KVM is enabled, but for both protected and non-protected VMs. + */ +static DEFINE_PER_CPU(struct pkvm_hyp_vcpu *, loaded_hyp_vcpu); + /* * Set trap register values based on features in ID_AA64PFR0. */ @@ -306,15 +312,30 @@ struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle, struct pkvm_hyp_vcpu *hyp_vcpu = NULL; struct pkvm_hyp_vm *hyp_vm; + /* Cannot load a new vcpu without putting the old one first. */ + if (__this_cpu_read(loaded_hyp_vcpu)) + return NULL; + hyp_spin_lock(&vm_table_lock); hyp_vm = get_vm_by_handle(handle); if (!hyp_vm || hyp_vm->nr_vcpus <= vcpu_idx) goto unlock; hyp_vcpu = hyp_vm->vcpus[vcpu_idx]; + + /* Ensure vcpu isn't loaded on more than one cpu simultaneously. */ + if (unlikely(hyp_vcpu->loaded_hyp_vcpu)) { + hyp_vcpu = NULL; + goto unlock; + } + + hyp_vcpu->loaded_hyp_vcpu = this_cpu_ptr(&loaded_hyp_vcpu); hyp_page_ref_inc(hyp_virt_to_page(hyp_vm)); unlock: hyp_spin_unlock(&vm_table_lock); + + if (hyp_vcpu) + __this_cpu_write(loaded_hyp_vcpu, hyp_vcpu); return hyp_vcpu; } @@ -323,10 +344,18 @@ void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu) struct pkvm_hyp_vm *hyp_vm = pkvm_hyp_vcpu_to_hyp_vm(hyp_vcpu); hyp_spin_lock(&vm_table_lock); + hyp_vcpu->loaded_hyp_vcpu = NULL; + __this_cpu_write(loaded_hyp_vcpu, NULL); hyp_page_ref_dec(hyp_virt_to_page(hyp_vm)); hyp_spin_unlock(&vm_table_lock); } +struct pkvm_hyp_vcpu *pkvm_get_loaded_hyp_vcpu(void) +{ + return __this_cpu_read(loaded_hyp_vcpu); + +} + struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle) { struct pkvm_hyp_vm *hyp_vm; diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c index f267bc2486a18..c2ef41fff079b 100644 --- a/arch/arm64/kvm/vgic/vgic-v3.c +++ b/arch/arm64/kvm/vgic/vgic-v3.c @@ -734,7 +734,8 @@ void vgic_v3_load(struct kvm_vcpu *vcpu) { struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3; - kvm_call_hyp(__vgic_v3_restore_vmcr_aprs, cpu_if); + if (likely(!is_protected_kvm_enabled())) + kvm_call_hyp(__vgic_v3_restore_vmcr_aprs, cpu_if); if (has_vhe()) __vgic_v3_activate_traps(cpu_if); @@ -746,7 +747,8 @@ void vgic_v3_put(struct kvm_vcpu *vcpu) { struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3; - kvm_call_hyp(__vgic_v3_save_vmcr_aprs, cpu_if); + if (likely(!is_protected_kvm_enabled())) + kvm_call_hyp(__vgic_v3_save_vmcr_aprs, cpu_if); WARN_ON(vgic_v4_put(vcpu)); if (has_vhe())