RISC-V: KVM: Fix the initial sample period value

The initial sample period value when counter value is not assigned
should be set to maximum value supported by the counter width.
Otherwise, it may result in spurious interrupts.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240420151741.962500-11-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>

diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 86391a5061dda98d534908a3d17ef78f2ff1fd9e..cee1b9ca4ec481c4abd67912b0731b42f70456e1 100644 (file)
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -39,7 +39,7 @@ static u64 kvm_pmu_get_sample_period(struct kvm_pmc *pmc)
        u64 sample_period;
 
        if (!pmc->counter_val)
-               sample_period = counter_val_mask + 1;
+               sample_period = counter_val_mask;
        else
                sample_period = (-pmc->counter_val) & counter_val_mask;