Re: [PATCH v3 05/10] KVM: arm64: Add trap configs for PMSDSFR_EL1

Joey Gouly
2025-07-09T11:32:25Z

Hi James!

On Thu, Jun 05, 2025 at 11:49:03AM +0100, James Clark wrote:
> SPE data source filtering (SPE_FEAT_FDS) adds a new register
> PMSDSFR_EL1, add the trap configs for it. PMSNEVFR_EL1 was also missing
> its VNCR offset so add it along with PMSDSFR_EL1.
>

A (well behaving) guest won't try access this because:
The presence of PMSDSFR_EL1 is checked by accessing PMSDSFR_EL1.FDS, which is
currently `undef_access` and we hide SPE from the guest in
read_sanitised_id_aa64dfr0_el1().

So makes sense it is just undef!

Reviewed-by: Joey Gouly <joey.gouly@arm.com>

Thanks,
Joey

> Tested-by: Leo Yan <leo.yan@arm.com>
> Signed-off-by: James Clark <james.clark@linaro.org>
> ---
> arch/arm64/include/asm/vncr_mapping.h | 2 ++
> arch/arm64/kvm/emulate-nested.c | 1 +
> arch/arm64/kvm/sys_regs.c | 1 +
> 3 files changed, 4 insertions(+)
>
> diff --git a/arch/arm64/include/asm/vncr_mapping.h b/arch/arm64/include/asm/vncr_mapping.h
> index 6f556e993644..dba0e58a5fac 100644
> --- a/arch/arm64/include/asm/vncr_mapping.h
> +++ b/arch/arm64/include/asm/vncr_mapping.h
> @@ -92,6 +92,8 @@
> #define VNCR_PMSICR_EL1 0x838
> #define VNCR_PMSIRR_EL1 0x840
> #define VNCR_PMSLATFR_EL1 0x848
> +#define VNCR_PMSNEVFR_EL1 0x850
> +#define VNCR_PMSDSFR_EL1 0x858
> #define VNCR_TRFCR_EL1 0x880
> #define VNCR_MPAM1_EL1 0x900
> #define VNCR_MPAMHCR_EL2 0x930
> diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
> index 3a384e9660b8..60bd8b7f0e5b 100644
> --- a/arch/arm64/kvm/emulate-nested.c
> +++ b/arch/arm64/kvm/emulate-nested.c
> @@ -1174,6 +1174,7 @@ static const struct encoding_to_trap_config encoding_to_cgt[] __initconst = {
> SR_TRAP(SYS_PMSIRR_EL1, CGT_MDCR_TPMS),
> SR_TRAP(SYS_PMSLATFR_EL1, CGT_MDCR_TPMS),
> SR_TRAP(SYS_PMSNEVFR_EL1, CGT_MDCR_TPMS),
> + SR_TRAP(SYS_PMSDSFR_EL1, CGT_MDCR_TPMS),
> SR_TRAP(SYS_TRFCR_EL1, CGT_MDCR_TTRF),
> SR_TRAP(SYS_TRBBASER_EL1, CGT_MDCR_E2TB),
> SR_TRAP(SYS_TRBLIMITR_EL1, CGT_MDCR_E2TB),
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index a6cf2888d150..4a88ba15c7df 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -3008,6 +3008,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
> { SYS_DESC(SYS_PMBLIMITR_EL1), undef_access },
> { SYS_DESC(SYS_PMBPTR_EL1), undef_access },
> { SYS_DESC(SYS_PMBSR_EL1), undef_access },
> + { SYS_DESC(SYS_PMSDSFR_EL1), undef_access },
> /* PMBIDR_EL1 is not trapped */
>
> { PMU_SYS_REG(PMINTENSET_EL1),
>
> --
> 2.34.1
>