On Mon, Feb 10, 2025 at 06:06:38PM +0000, Will Deacon wrote:
On Mon, Feb 10, 2025 at 04:59:56PM +0000, Mark Rutland wrote:
On Mon, Feb 10, 2025 at 04:12:43PM +0000, Will Deacon wrote:
On Thu, Feb 06, 2025 at 02:10:56PM +0000, Mark Rutland wrote:
| static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code) | { | ... | | /* Valid trap */ | | /* | * Enable everything EL2 might need to save/restore state. | * Maybe each of the bits should depend on system_has_xxx() | */ | cpacr_clear_set(0, CPACR_EL1_FPEN | CPACR_EL1_ZEN | CPACR_EL1_SMEN */ | isb(); | | ... | | /* Write out the host state if it's in the registers */ | if (is_protected_kvm_enabled() && host_owns_fp_regs()) | kvm_hyp_save_fpsimd_host(vcpu); | | /* Restore guest state */ | | ... | | /* | * Enable traps for the VCPU. The ERET will cause the traps to | * take effect in the guest, so no ISB is necessary. | */ | cpacr_guest = CPACR_EL1_FPEN; | if (vcpu_has_sve(vcpu)) | cpacr_guest |= CPACR_EL1_ZEN; | if (vcpu_has_sme(vcpu)) // whenever we add this | cpacr_guest |= CPACR_EL1_SMEN; | cpacr_clear_set(CPACR_EL1_FPEN | CPACR_EL1_ZEN | CPACR_EL1_SMEN, | cpacr_guest); | | return true; | }
... where we'd still have the CPACR write to re-enable traps, but it'd be unconditional, and wouldn't need an extra ISB.
If that makes sense to you, I can go spin that as a subsequent cleanup atop this series.
That looks very clean, yes please! Don't forget to drop the part from kvm_hyp_save_fpsimd_host() too.
Yep, that was the idea!
To avoid confusion: I've sent out v3 of this series *without* the change, and I'll prepare that as a follow-up.
Mark.