Any guest must not get access to any hpmcounter including cycle/instret without any checks. We achieve that by disabling all the bits except TM bit in hcounteren. However, instret and cycle access for guest user space can be enabled upon explicit request (via ONE REG) or on first trap from VU mode to maintain ABI requirement in the future. This patch doesn't support that as ONE REG interface is not settled yet. Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx> Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx> --- arch/riscv/kvm/main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c index 58c5489..c5d400f 100644 --- a/arch/riscv/kvm/main.c +++ b/arch/riscv/kvm/main.c @@ -49,7 +49,8 @@ int kvm_arch_hardware_enable(void) hideleg |= (1UL << IRQ_VS_EXT); csr_write(CSR_HIDELEG, hideleg); - csr_write(CSR_HCOUNTEREN, -1UL); + /* VS should access only the time counter directly. Everything else should trap */ + csr_write(CSR_HCOUNTEREN, 0x02); csr_write(CSR_HVIP, 0); -- 2.25.1
