[PATCH v2 09/18] KVM: arm64: Introduce __pkvm_vcpu_{load,put}()
Quentin Perret
qperret at google.com
Tue Dec 3 02:37:26 PST 2024
From: Marc Zyngier <maz at kernel.org>
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.
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
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 ca2590344313..89c0fac69551 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 a102c3aebdbc..55cc62b2f469 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 f361d8b91930..be52c5b15e21 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 6aa0b13d86e5..95d78db315b3 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 4db88bedf8d5..d5c23449a64c 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 f267bc2486a1..c2ef41fff079 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())
--
2.47.0.338.g60cca15819-goog
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