[PATCH v2 2/2] RISCV: KVM: Introduce vcpu->reset_cntx_lock

From: Yong-Xuan Wang
Date: Wed Apr 17 2024 - 03:46:02 EST


Originally, the use of kvm->lock in SBI_EXT_HSM_HART_START also avoids
the simultaneous updates to the reset context of target VCPU. Since this
lock has been replace with vcpu->mp_state_lock, and this new lock also
protects the vcpu->mp_state. We have to add a separate lock for
vcpu->reset_cntx.

Signed-off-by: Yong-Xuan Wang <yongxuan.wang@xxxxxxxxxx>
---
arch/riscv/include/asm/kvm_host.h | 1 +
arch/riscv/kvm/vcpu.c | 6 ++++++
arch/riscv/kvm/vcpu_sbi_hsm.c | 3 +++
3 files changed, 10 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 64d35a8c908c..664d1bb00368 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -211,6 +211,7 @@ struct kvm_vcpu_arch {

/* CPU context upon Guest VCPU reset */
struct kvm_cpu_context guest_reset_context;
+ spinlock_t reset_cntx_lock;

/* CPU CSR context upon Guest VCPU reset */
struct kvm_vcpu_csr guest_reset_csr;
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 70937f71c3c4..1a2236e4c7f3 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -64,7 +64,9 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)

memcpy(csr, reset_csr, sizeof(*csr));

+ spin_lock(&vcpu->arch.reset_cntx_lock);
memcpy(cntx, reset_cntx, sizeof(*cntx));
+ spin_unlock(&vcpu->arch.reset_cntx_lock);

kvm_riscv_vcpu_fp_reset(vcpu);

@@ -121,12 +123,16 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
spin_lock_init(&vcpu->arch.hfence_lock);

/* Setup reset state of shadow SSTATUS and HSTATUS CSRs */
+ spin_lock_init(&vcpu->arch.reset_cntx_lock);
+
+ spin_lock(&vcpu->arch.reset_cntx_lock);
cntx = &vcpu->arch.guest_reset_context;
cntx->sstatus = SR_SPP | SR_SPIE;
cntx->hstatus = 0;
cntx->hstatus |= HSTATUS_VTW;
cntx->hstatus |= HSTATUS_SPVP;
cntx->hstatus |= HSTATUS_SPV;
+ spin_unlock(&vcpu->arch.reset_cntx_lock);

if (kvm_riscv_vcpu_alloc_vector_context(vcpu, cntx))
return -ENOMEM;
diff --git a/arch/riscv/kvm/vcpu_sbi_hsm.c b/arch/riscv/kvm/vcpu_sbi_hsm.c
index 115a6c6525fd..cc5038b90e02 100644
--- a/arch/riscv/kvm/vcpu_sbi_hsm.c
+++ b/arch/riscv/kvm/vcpu_sbi_hsm.c
@@ -31,6 +31,7 @@ static int kvm_sbi_hsm_vcpu_start(struct kvm_vcpu *vcpu)
goto out;
}

+ spin_lock(&target_vcpu->arch.reset_cntx_lock);
reset_cntx = &target_vcpu->arch.guest_reset_context;
/* start address */
reset_cntx->sepc = cp->a1;
@@ -38,6 +39,8 @@ static int kvm_sbi_hsm_vcpu_start(struct kvm_vcpu *vcpu)
reset_cntx->a0 = target_vcpuid;
/* private data passed from kernel */
reset_cntx->a1 = cp->a2;
+ spin_unlock(&target_vcpu->arch.reset_cntx_lock);
+
kvm_make_request(KVM_REQ_VCPU_RESET, target_vcpu);

__kvm_riscv_vcpu_power_on(target_vcpu);
--
2.17.1