[PATCH v1 6/7] KVM: arm64: Eagerly restore host fpsimd/sve state in pKVM
Oliver Upton
oliver.upton at linux.dev
Fri May 17 10:09:31 PDT 2024
Hi Fuad,
On Fri, May 17, 2024 at 02:18:13PM +0100, Fuad Tabba wrote:
> static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu)
> {
> - __fpsimd_save_state(*host_data_ptr(fpsimd_state));
> + /*
> + * Non-protected kvm relies on the host restoring its sve state.
> + * Protected kvm restores the host's sve state as not to reveal that
> + * fpsimd was used by a guest nor leak upper sve bits.
> + */
> + if (unlikely(is_protected_kvm_enabled() && system_supports_sve())) {
> + __hyp_sve_save_host();
> +
> + /* Re-enable SVE traps for guests that do not support it. */
> + if (!vcpu_has_sve(vcpu))
> + sysreg_clear_set(cptr_el2, 0, CPTR_EL2_TZ);
This doesn't account for hVHE. I wonder we'd be better off abstracting
CPTR_EL2 behind a helper wherever it gets used in nVHE and translate
into the VHE-format behind the scenes:
static inline void __cptr_clear_set_hvhe(u64 cptr_clr, u64 cptr_set)
{
u64 clr = 0, set = 0;
if (cptr_clr & CPTR_EL2_TFP)
set |= CPACR_ELx_FPEN;
if (cptr_clr & CPTR_EL2_TZ)
set |= CPACR_ELx_ZEN;
if (cptr_clr & CPTR_EL2_TSM)
set |= CPACR_ELx_SMEN;
if (cptr_set & CPTR_EL2_TFP)
clr |= CPACR_ELx_FPEN;
if (cptr_set & CPTR_EL2_TZ)
clr |= CPACR_ELx_ZEN;
if (cptr_set & CPTR_EL2_TSM)
clr |= CPACR_ELx_SMEN;
sysreg_clear_set(cpacr_el1, clr, set);
}
static inline void cptr_clear_set(u64 clr, u64 set)
{
if (has_hvhe())
__cptr_clear_set_hvhe(clr, set);
else
sysreg_clear_set(cptr_el2, clr, set);
}
--
Thanks,
Oliver
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