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ANDROID: KVM: arm64: Introduce new spinlock for hypervisor VM vCPUs[] array

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The vCPU structures of the hypervisor VM struct claim to be protected
by 'vm_table_lock', however:

  1. This doesn't appear to be the case on the PSCI paths, where the
     array is walked locklessly when accessing the target vCPU

  2. The 'vm_table_lock' serialises across all VMs, so is overkill

Introduce a new per-VM spinlock for the vCPU array and ensure that it is
held whilst accessing the data structure.

Bug: 357781595
Change-Id: I821639f0c698696e07bf0c228c18beea83434a03
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <willdeacon@google.com>
This commit is contained in:
Will Deacon
2023-07-03 14:39:53 +01:00
committed by Keir Fraser
parent b8c35a6cd3
commit 7d9f60ddf7
2 changed files with 26 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/arm64/kvm/hyp/include/nvhe/pkvm.h
+1 -1
View File
@@ -57,9 +57,9 @@ struct pkvm_hyp_vm {
/*
* The number of vcpus initialized and ready to run.
* Modifying this is protected by 'vm_table_lock'.
*/
unsigned int nr_vcpus;
hyp_spinlock_t vcpus_lock;
/* Array of the hyp vCPU structures for this VM. */
struct pkvm_hyp_vcpu *vcpus[];
arch/arm64/kvm/hyp/nvhe/pkvm.c
+25 -14
View File
@@ -324,7 +324,7 @@ struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle,
hyp_read_lock(&vm_table_lock);
hyp_vm = get_vm_by_handle(handle);
if (!hyp_vm || hyp_vm->nr_vcpus <= vcpu_idx)
if (!hyp_vm || READ_ONCE(hyp_vm->nr_vcpus) <= vcpu_idx)
goto unlock;
hyp_vcpu = hyp_vm->vcpus[vcpu_idx];
@@ -492,6 +492,7 @@ static void init_pkvm_hyp_vm(struct kvm *host_kvm, struct pkvm_hyp_vm *hyp_vm,
hyp_vm->kvm.arch.mmu.last_vcpu_ran = (int __percpu *)last_ran;
memset(last_ran, -1, pkvm_get_last_ran_size());
pkvm_init_features_from_host(hyp_vm, host_kvm);
hyp_spin_lock_init(&hyp_vm->vcpus_lock);
}
static int pkvm_vcpu_init_sve(struct pkvm_hyp_vcpu *hyp_vcpu, struct kvm_vcpu *host_vcpu)
@@ -795,28 +796,32 @@ int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu,
if (!hyp_vcpu)
return -ENOMEM;
hyp_write_lock(&vm_table_lock);
hyp_read_lock(&vm_table_lock);
hyp_vm = get_vm_by_handle(handle);
if (!hyp_vm) {
ret = -ENOENT;
goto unlock;
goto unlock_vm;
}
hyp_spin_lock(&hyp_vm->vcpus_lock);
idx = hyp_vm->nr_vcpus;
if (idx >= hyp_vm->kvm.created_vcpus) {
ret = -EINVAL;
goto unlock;
goto unlock_vcpus;
}
ret = init_pkvm_hyp_vcpu(hyp_vcpu, hyp_vm, host_vcpu, idx);
if (ret)
goto unlock;
goto unlock_vcpus;
hyp_vm->vcpus[idx] = hyp_vcpu;
hyp_vm->nr_vcpus++;
unlock:
hyp_write_unlock(&vm_table_lock);
unlock_vcpus:
hyp_spin_unlock(&hyp_vm->vcpus_lock);
unlock_vm:
hyp_read_unlock(&vm_table_lock);
if (ret) {
unmap_donated_memory(hyp_vcpu, sizeof(*hyp_vcpu));
@@ -941,18 +946,22 @@ void pkvm_reset_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
struct pkvm_hyp_vcpu *pkvm_mpidr_to_hyp_vcpu(struct pkvm_hyp_vm *hyp_vm,
u64 mpidr)
{
struct pkvm_hyp_vcpu *hyp_vcpu;
int i;
mpidr &= MPIDR_HWID_BITMASK;
hyp_spin_lock(&hyp_vm->vcpus_lock);
for (i = 0; i < hyp_vm->nr_vcpus; i++) {
struct pkvm_hyp_vcpu *hyp_vcpu = hyp_vm->vcpus[i];
hyp_vcpu = hyp_vm->vcpus[i];
if (mpidr == kvm_vcpu_get_mpidr_aff(&hyp_vcpu->vcpu))
return hyp_vcpu;
goto unlock;
}
return NULL;
hyp_vcpu = NULL;
unlock:
hyp_spin_unlock(&hyp_vm->vcpus_lock);
return hyp_vcpu;
}
/*
@@ -1051,6 +1060,7 @@ static bool pvm_psci_vcpu_affinity_info(struct pkvm_hyp_vcpu *hyp_vcpu)
* then if at least one is PENDING_ON then return PENDING_ON.
* Otherwise, return OFF.
*/
hyp_spin_lock(&hyp_vm->vcpus_lock);
for (i = 0; i < hyp_vm->nr_vcpus; i++) {
struct pkvm_hyp_vcpu *target = hyp_vm->vcpus[i];
@@ -1067,19 +1077,20 @@ static bool pvm_psci_vcpu_affinity_info(struct pkvm_hyp_vcpu *hyp_vcpu)
break;
case PSCI_0_2_AFFINITY_LEVEL_ON:
ret = PSCI_0_2_AFFINITY_LEVEL_ON;
goto done;
goto unlock;
case PSCI_0_2_AFFINITY_LEVEL_OFF:
break;
default:
ret = PSCI_RET_INTERNAL_FAILURE;
goto done;
goto unlock;
}
}
}
if (!matching_cpus)
ret = PSCI_RET_INVALID_PARAMS;
unlock:
hyp_spin_unlock(&hyp_vm->vcpus_lock);
done:
/* Nothing to be handled by the host. Go back to the guest. */
smccc_set_retval(vcpu, ret, 0, 0, 0);