diff options
| author | Yong-Xuan Wang <yongxuan.wang@sifive.com> | 2024-04-17 15:45:25 +0800 |
|---|---|---|
| committer | Anup Patel <anup@brainfault.org> | 2024-04-22 10:37:11 +0530 |
| commit | 2121cadec45aaf61fa45b3aa3d99723ed4e6683a (patch) | |
| tree | 4e2988e18b8011af58bca07e987a3c48d73bea6b /arch/riscv/kvm/vcpu_sbi_hsm.c | |
| parent | f1c48c1ec73538a8e49695445a0fbc52156aac42 (diff) | |
RISCV: KVM: Introduce mp_state_lock to avoid lock inversion
Documentation/virt/kvm/locking.rst advises that kvm->lock should be
acquired outside vcpu->mutex and kvm->srcu. However, when KVM/RISC-V
handling SBI_EXT_HSM_HART_START, the lock ordering is vcpu->mutex,
kvm->srcu then kvm->lock.
Although the lockdep checking no longer complains about this after commit
f0f44752f5f6 ("rcu: Annotate SRCU's update-side lockdep dependencies"),
it's necessary to replace kvm->lock with a new dedicated lock to ensure
only one hart can execute the SBI_EXT_HSM_HART_START call for the target
hart simultaneously.
Additionally, this patch also rename "power_off" to "mp_state" with two
possible values. The vcpu->mp_state_lock also protects the access of
vcpu->mp_state.
Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240417074528.16506-2-yongxuan.wang@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Diffstat (limited to 'arch/riscv/kvm/vcpu_sbi_hsm.c')
| -rw-r--r-- | arch/riscv/kvm/vcpu_sbi_hsm.c | 39 |
1 files changed, 27 insertions, 12 deletions
diff --git a/arch/riscv/kvm/vcpu_sbi_hsm.c b/arch/riscv/kvm/vcpu_sbi_hsm.c index 7dca0e9381d9..827d946ab871 100644 --- a/arch/riscv/kvm/vcpu_sbi_hsm.c +++ b/arch/riscv/kvm/vcpu_sbi_hsm.c @@ -18,12 +18,18 @@ static int kvm_sbi_hsm_vcpu_start(struct kvm_vcpu *vcpu) struct kvm_cpu_context *cp = &vcpu->arch.guest_context; struct kvm_vcpu *target_vcpu; unsigned long target_vcpuid = cp->a0; + int ret = 0; target_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, target_vcpuid); if (!target_vcpu) return SBI_ERR_INVALID_PARAM; - if (!target_vcpu->arch.power_off) - return SBI_ERR_ALREADY_AVAILABLE; + + spin_lock(&target_vcpu->arch.mp_state_lock); + + if (!kvm_riscv_vcpu_stopped(target_vcpu)) { + ret = SBI_ERR_ALREADY_AVAILABLE; + goto out; + } reset_cntx = &target_vcpu->arch.guest_reset_context; /* start address */ @@ -34,19 +40,31 @@ static int kvm_sbi_hsm_vcpu_start(struct kvm_vcpu *vcpu) reset_cntx->a1 = cp->a2; kvm_make_request(KVM_REQ_VCPU_RESET, target_vcpu); - kvm_riscv_vcpu_power_on(target_vcpu); + __kvm_riscv_vcpu_power_on(target_vcpu); - return 0; +out: + spin_unlock(&target_vcpu->arch.mp_state_lock); + + return ret; } static int kvm_sbi_hsm_vcpu_stop(struct kvm_vcpu *vcpu) { - if (vcpu->arch.power_off) - return SBI_ERR_FAILURE; + int ret = 0; - kvm_riscv_vcpu_power_off(vcpu); + spin_lock(&vcpu->arch.mp_state_lock); - return 0; + if (kvm_riscv_vcpu_stopped(vcpu)) { + ret = SBI_ERR_FAILURE; + goto out; + } + + __kvm_riscv_vcpu_power_off(vcpu); + +out: + spin_unlock(&vcpu->arch.mp_state_lock); + + return ret; } static int kvm_sbi_hsm_vcpu_get_status(struct kvm_vcpu *vcpu) @@ -58,7 +76,7 @@ static int kvm_sbi_hsm_vcpu_get_status(struct kvm_vcpu *vcpu) target_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, target_vcpuid); if (!target_vcpu) return SBI_ERR_INVALID_PARAM; - if (!target_vcpu->arch.power_off) + if (!kvm_riscv_vcpu_stopped(target_vcpu)) return SBI_HSM_STATE_STARTED; else if (vcpu->stat.generic.blocking) return SBI_HSM_STATE_SUSPENDED; @@ -71,14 +89,11 @@ static int kvm_sbi_ext_hsm_handler(struct kvm_vcpu *vcpu, struct kvm_run *run, { int ret = 0; struct kvm_cpu_context *cp = &vcpu->arch.guest_context; - struct kvm *kvm = vcpu->kvm; unsigned long funcid = cp->a6; switch (funcid) { case SBI_EXT_HSM_HART_START: - mutex_lock(&kvm->lock); ret = kvm_sbi_hsm_vcpu_start(vcpu); - mutex_unlock(&kvm->lock); break; case SBI_EXT_HSM_HART_STOP: ret = kvm_sbi_hsm_vcpu_stop(vcpu); |