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RISCV: KVM: Introduce mp_state_lock to avoid lock inversion

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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
f0f44752f5 ("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>
This commit is contained in:
Yong-Xuan Wang
2024-04-17 15:45:25 +08:00
committed by Anup Patel
parent f1c48c1ec7
commit 2121cadec4
4 changed files with 73 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
arch/riscv/include/asm/kvm_host.h
View File

@@ -264,8 +264,9 @@ struct kvm_vcpu_arch {
/* Cache pages needed to program page tables with spinlock held */
struct kvm_mmu_memory_cache mmu_page_cache;
/* VCPU power-off state */
bool power_off;
/* VCPU power state */
struct kvm_mp_state mp_state;
spinlock_t mp_state_lock;
/* Don't run the VCPU (blocked) */
bool pause;
@@ -386,8 +387,11 @@ int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu);
bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, u64 mask);
void __kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
void __kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
bool kvm_riscv_vcpu_stopped(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu);