[PATCH v2 2/7] KVM: arm64: Abstract set/clear of CPTR_EL2 bits behind helper
Marc Zyngier
maz at kernel.org
Tue May 21 14:08:46 PDT 2024
On Tue, 21 May 2024 17:37:15 +0100,
Fuad Tabba <tabba at google.com> wrote:
>
> The same traps controlled by CPTR_EL2 or CPACR_EL1 need to be
> toggled in different parts of the code, but the exact bits and
> their polarity differ between these two formats and the mode
> (vhe/nvhe/hvhe).
>
> To reduce the amount of duplicated code and the chance of getting
> the wrong bit/polarity or missing a field, abstract the set/clear
> of CPTR_EL2 bits behind a helper.
>
> Since (h)VHE is the way of the future, use the CPACR_EL1 format,
> which is a subset of the VHE CPTR_EL2, as a reference.
>
> No functional change intended.
>
> Suggested-by: Oliver Upton <oliver.upton at linux.dev>
> Signed-off-by: Fuad Tabba <tabba at google.com>
> ---
> arch/arm64/include/asm/kvm_emulate.h | 34 +++++++++++++++++++++++++
> arch/arm64/kvm/hyp/include/hyp/switch.h | 17 +++----------
> arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 +----
> 3 files changed, 39 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
> index 501e3e019c93..74837d1762e5 100644
> --- a/arch/arm64/include/asm/kvm_emulate.h
> +++ b/arch/arm64/include/asm/kvm_emulate.h
> @@ -557,6 +557,40 @@ static __always_inline void kvm_incr_pc(struct kvm_vcpu *vcpu)
> vcpu_set_flag((v), e); \
> } while (0)
>
> +
> +static inline void __cptr_clear_set_nvhe(u64 cpacr_clr, u64 cpacr_set)
> +{
> + u64 clr = 0, set = 0;
> +
> + if (cpacr_clr & CPACR_ELx_FPEN)
> + set |= CPTR_EL2_TFP;
> + if (cpacr_clr & CPACR_ELx_ZEN)
> + set |= CPTR_EL2_TZ;
> + if (cpacr_clr & CPACR_ELx_SMEN)
These 3 fields are actually pairs of bits. Can we have a compile-time
check that both bits are set?
> + set |= CPTR_EL2_TSM;
> + if (cpacr_clr & CPACR_ELx_TTA)
> + clr |= CPTR_EL2_TTA;
How about TCPAC, TAM, and E0POE?
> +
> + if (cpacr_set & CPACR_ELx_FPEN)
> + clr |= CPTR_EL2_TFP;
> + if (cpacr_set & CPACR_ELx_ZEN)
> + clr |= CPTR_EL2_TZ;
> + if (cpacr_set & CPACR_ELx_SMEN)
> + clr |= CPTR_EL2_TSM;
> + if (cpacr_set & CPACR_ELx_TTA)
> + set |= CPTR_EL2_TTA;
The duplication is pretty unfortunate. Having a single helper that
translate a register layout into another would be better.
> +
> + sysreg_clear_set(cptr_el2, clr, set);
And omit this...
> +}
> +
> +static inline void cpacr_clear_set(u64 clr, u64 set)
> +{
> + if (has_vhe() || has_hvhe())
> + sysreg_clear_set(cpacr_el1, clr, set);
> + else
> + __cptr_clear_set_nvhe(clr, set);
So that this could read as:
sysreg_clear_set(cptr_el2, cpacr_to_cptr(clr), cpacr_to_cptr(set));
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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