On Tue, Jul 18 2023, Jing Zhang <jingzhangos@xxxxxxxxxx> wrote:
> All valid fields in ID_AA64DFR0_EL1 and ID_DFR0_EL1 are writable
> from usrespace with this change.
Typo: s/usrespace/userspace/
>
> Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
> ---
> arch/arm64/kvm/sys_regs.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 053d8057ff1e..f33aec83f1b4 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -2008,7 +2008,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
> .set_user = set_id_dfr0_el1,
> .visibility = aa32_id_visibility,
> .reset = read_sanitised_id_dfr0_el1,
> - .val = ID_DFR0_EL1_PerfMon_MASK, },
> + .val = GENMASK(63, 0), },
> ID_HIDDEN(ID_AFR0_EL1),
> AA32_ID_SANITISED(ID_MMFR0_EL1),
> AA32_ID_SANITISED(ID_MMFR1_EL1),
> @@ -2057,7 +2057,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
> .get_user = get_id_reg,
> .set_user = set_id_aa64dfr0_el1,
> .reset = read_sanitised_id_aa64dfr0_el1,
> - .val = ID_AA64DFR0_EL1_PMUVer_MASK, },
> + .val = GENMASK(63, 0), },
> ID_SANITISED(ID_AA64DFR1_EL1),
> ID_UNALLOCATED(5,2),
> ID_UNALLOCATED(5,3),
How does userspace find out whether a given id reg is actually writable,
other than trying to write to it?
