On 07/12/17 17:06, Christoffer Dall wrote:
> On non-VHE systems we need to save the ELR_EL2 and SPSR_EL2 so that we
> can return to the host in EL1 in the same state and location where we
> issued a hypercall to EL2, but these registers don't contain anything
> important on VHE, because all of the host runs in EL2. Therefore,
If I may refine the rational: ELR_EL2 and SPSR_EL2 are not useful here
because we never enter a guest as a result of an exception entry that
would be directly handled by KVM. The kernel entry code already saves
ELR_EL1/SPSR_EL1 on exception entry, which is enough.
> factor out these registers into separate save/restore functions, making
> it easy to exclude them from the VHE world-switch path later on.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> ---
> arch/arm64/kvm/hyp/sysreg-sr.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> index a12112494f75..479de0f0dd07 100644
> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> @@ -71,6 +71,10 @@ static void __hyp_text __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
> ctxt->gp_regs.sp_el1 = read_sysreg(sp_el1);
> ctxt->gp_regs.elr_el1 = read_sysreg_el1(elr);
> ctxt->gp_regs.spsr[KVM_SPSR_EL1]= read_sysreg_el1(spsr);
> +}
> +
> +static void __hyp_text __sysreg_save_el2_return_state(struct kvm_cpu_context *ctxt)
> +{
> ctxt->gp_regs.regs.pc = read_sysreg_el2(elr);
> ctxt->gp_regs.regs.pstate = read_sysreg_el2(spsr);
> }
> @@ -80,6 +84,7 @@ void __hyp_text __sysreg_save_state_nvhe(struct kvm_cpu_context *ctxt)
> __sysreg_save_el1_state(ctxt);
> __sysreg_save_common_state(ctxt);
> __sysreg_save_user_state(ctxt);
> + __sysreg_save_el2_return_state(ctxt);
> }
>
> void sysreg_save_host_state_vhe(struct kvm_cpu_context *ctxt)
> @@ -93,6 +98,7 @@ void sysreg_save_guest_state_vhe(struct kvm_cpu_context *ctxt)
> __sysreg_save_el1_state(ctxt);
> __sysreg_save_common_state(ctxt);
> __sysreg_save_user_state(ctxt);
> + __sysreg_save_el2_return_state(ctxt);
> }
>
> static void __hyp_text __sysreg_restore_common_state(struct kvm_cpu_context *ctxt)
> @@ -137,6 +143,11 @@ static void __hyp_text __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
> write_sysreg(ctxt->gp_regs.sp_el1, sp_el1);
> write_sysreg_el1(ctxt->gp_regs.elr_el1, elr);
> write_sysreg_el1(ctxt->gp_regs.spsr[KVM_SPSR_EL1],spsr);
> +}
> +
> +static void __hyp_text
> +__sysreg_restore_el2_return_state(struct kvm_cpu_context *ctxt)
> +{
> write_sysreg_el2(ctxt->gp_regs.regs.pc, elr);
> write_sysreg_el2(ctxt->gp_regs.regs.pstate, spsr);
> }
> @@ -146,6 +157,7 @@ void __hyp_text __sysreg_restore_state_nvhe(struct kvm_cpu_context *ctxt)
> __sysreg_restore_el1_state(ctxt);
> __sysreg_restore_common_state(ctxt);
> __sysreg_restore_user_state(ctxt);
> + __sysreg_restore_el2_return_state(ctxt);
> }
>
> void sysreg_restore_host_state_vhe(struct kvm_cpu_context *ctxt)
> @@ -159,6 +171,7 @@ void sysreg_restore_guest_state_vhe(struct kvm_cpu_context *ctxt)
> __sysreg_restore_el1_state(ctxt);
> __sysreg_restore_common_state(ctxt);
> __sysreg_restore_user_state(ctxt);
> + __sysreg_restore_el2_return_state(ctxt);
> }
>
> static void __hyp_text __fpsimd32_save_state(struct kvm_cpu_context *ctxt)
>
Otherwise:
Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>
M.
--
Jazz is not dead. It just smells funny...
