On 07/12/17 17:06, Christoffer Dall wrote:
> There's a semantic difference between the EL1 registers that control
> operation of a kernel running in EL1 and EL1 registers that only control
> userspace execution in EL0. Since we can defer saving/restoring the
> latter, move them into their own function.
>
> We also take this chance to rename the function saving/restoring the
> remaining system register to make it clear this function deals with
> the EL1 system registers.
>
> No functional change.
>
> Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> ---
>
> Notes:
> Changes since v1:
> - Added comment about sp_el0 to common save sysreg save/restore functions
>
> arch/arm64/kvm/hyp/sysreg-sr.c | 44 +++++++++++++++++++++++++++++++-----------
> 1 file changed, 33 insertions(+), 11 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> index 68a7d164e5e1..bbfb4d01af88 100644
> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> @@ -33,15 +33,24 @@ static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { }
> */
>
> static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt)
> +{
> + ctxt->sys_regs[MDSCR_EL1] = read_sysreg(mdscr_el1);
> +
> + /*
> + * The host arm64 Linux uses sp_el0 to point to 'current' and it must
> + * therefore be saved/restored on every entry/exit to/from the guest.
> + */
> + ctxt->gp_regs.regs.sp = read_sysreg(sp_el0);
> +}
> +
> +static void __hyp_text __sysreg_save_user_state(struct kvm_cpu_context *ctxt)
> {
> ctxt->sys_regs[ACTLR_EL1] = read_sysreg(actlr_el1);
What is the rational for keeping ACTLR_EL1 as part of the user state?
> ctxt->sys_regs[TPIDR_EL0] = read_sysreg(tpidr_el0);
> ctxt->sys_regs[TPIDRRO_EL0] = read_sysreg(tpidrro_el0);
> - ctxt->sys_regs[MDSCR_EL1] = read_sysreg(mdscr_el1);
> - ctxt->gp_regs.regs.sp = read_sysreg(sp_el0);
> }
>
> -static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
> +static void __hyp_text __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
> {
> ctxt->sys_regs[MPIDR_EL1] = read_sysreg(vmpidr_el2);
> ctxt->sys_regs[CSSELR_EL1] = read_sysreg(csselr_el1);
> @@ -70,31 +79,42 @@ static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
> }
>
> static hyp_alternate_select(__sysreg_call_save_host_state,
> - __sysreg_save_state, __sysreg_do_nothing,
> + __sysreg_save_el1_state, __sysreg_do_nothing,
> ARM64_HAS_VIRT_HOST_EXTN);
>
> void __hyp_text __sysreg_save_host_state(struct kvm_cpu_context *ctxt)
> {
> __sysreg_call_save_host_state()(ctxt);
> __sysreg_save_common_state(ctxt);
> + __sysreg_save_user_state(ctxt);
> }
>
> void __hyp_text __sysreg_save_guest_state(struct kvm_cpu_context *ctxt)
> {
> - __sysreg_save_state(ctxt);
> + __sysreg_save_el1_state(ctxt);
> __sysreg_save_common_state(ctxt);
> + __sysreg_save_user_state(ctxt);
> }
>
> static void __hyp_text __sysreg_restore_common_state(struct kvm_cpu_context *ctxt)
> {
> - write_sysreg(ctxt->sys_regs[ACTLR_EL1], actlr_el1);
> - write_sysreg(ctxt->sys_regs[TPIDR_EL0], tpidr_el0);
> - write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], tpidrro_el0);
> write_sysreg(ctxt->sys_regs[MDSCR_EL1], mdscr_el1);
> +
> + /*
> + * The host arm64 Linux uses sp_el0 to point to 'current' and it must
> + * therefore be saved/restored on every entry/exit to/from the guest.
> + */
> write_sysreg(ctxt->gp_regs.regs.sp, sp_el0);
> }
>
> -static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
> +static void __hyp_text __sysreg_restore_user_state(struct kvm_cpu_context *ctxt)
> +{
> + write_sysreg(ctxt->sys_regs[ACTLR_EL1], actlr_el1);
Same here.
> + write_sysreg(ctxt->sys_regs[TPIDR_EL0], tpidr_el0);
> + write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], tpidrro_el0);
> +}
> +
> +static void __hyp_text __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
> {
> write_sysreg(ctxt->sys_regs[MPIDR_EL1], vmpidr_el2);
> write_sysreg(ctxt->sys_regs[CSSELR_EL1], csselr_el1);
> @@ -123,19 +143,21 @@ static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
> }
>
> static hyp_alternate_select(__sysreg_call_restore_host_state,
> - __sysreg_restore_state, __sysreg_do_nothing,
> + __sysreg_restore_el1_state, __sysreg_do_nothing,
> ARM64_HAS_VIRT_HOST_EXTN);
>
> void __hyp_text __sysreg_restore_host_state(struct kvm_cpu_context *ctxt)
> {
> __sysreg_call_restore_host_state()(ctxt);
> __sysreg_restore_common_state(ctxt);
> + __sysreg_restore_user_state(ctxt);
> }
>
> void __hyp_text __sysreg_restore_guest_state(struct kvm_cpu_context *ctxt)
> {
> - __sysreg_restore_state(ctxt);
> + __sysreg_restore_el1_state(ctxt);
> __sysreg_restore_common_state(ctxt);
> + __sysreg_restore_user_state(ctxt);
> }
>
> static void __hyp_text __fpsimd32_save_state(struct kvm_cpu_context *ctxt)
>
I think we should move ACTLR_EL1 to the EL1 state, allowing it to be
lazily switched. See the note in D10.2.1 that recommends a VHE enabled
system to have ACTLR_EL1 as a guest-only register.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
