| Message ID | 20171207170630.592-16-christoffer.dall@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@redhat.com> > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> > --- > > 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.
On Mon, Dec 11, 2017 at 10:14:23AM +0000, Marc Zyngier wrote: > 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@redhat.com> > > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> > > --- > > > > 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? > The rationale was that I missed the note you pointed me to below, and therefore I figured that ACTLR_EL1 couldn't affect the host kernel, because it runs in EL2, but could affect host userspace, which is incorrect. So I was basically just being overlay cautious. > > 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 for this pointer. I will adjust the code as you suggest. -Christoffer
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); 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); + 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)