[PATCH v1 2/3] RISC-V: KVM: Report snapshot write failure to the guest

[SeungJu Cheon]

If kvm_vcpu_write_guest() fails while updating the PMU snapshot area
on counter stop, the guest may receive SBI_SUCCESS without the
snapshot being updated, leaving stale data in shared memory.

Return SBI_ERR_FAILURE when the snapshot write fails.

Fixes: c2f41ddbcdd7 ("RISC-V: KVM: Implement SBI PMU Snapshot feature")
Signed-off-by: SeungJu Cheon <suunj1331 at gmail.com>
---
 arch/riscv/kvm/vcpu_pmu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 56dd5b1b2846..45dd5233340d 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -723,9 +723,10 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
 		}
 	}
 
-	if (shmem_needs_update)
-		kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata,
-					     sizeof(struct riscv_pmu_snapshot_data));
+	if (shmem_needs_update &&
+	    kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata,
+				 sizeof(struct riscv_pmu_snapshot_data)))
+		sbiret = SBI_ERR_FAILURE;
 
 out:
 	retdata->err_val = sbiret;
-- 
2.52.0