From: Christoffer Dall <christoffer.d...@linaro.org> 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.
The ARMv8 ARM (ARM DDI 0487C.a) Section D10.2.1 recommends that ACTLR_EL1 has no effect on the processor when running the VHE host, and we can therefore move this register into the EL1 state which is only saved/restored on vcpu_put/load for a VHE host. 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. Reviewed-by: Andrew Jones <drjo...@redhat.com> Reviewed-by: Marc Zyngier <marc.zyng...@arm.com> Signed-off-by: Christoffer Dall <christoffer.d...@linaro.org> --- Notes: Changes since v4: - Clarified rationale for deferring ACTLR_EL1 in the commit message. Changes since v3: - Correct the comment about ACTLR_EL1 and adjust commit text. Changes since v2: - Save restore ACTLR_EL1 as part of the EL1 registers state instead of the user register state, as ACTLR_EL1 can't affect the host's execution on VHE systems. Changes since v1: - Added comment about sp_el0 to common save sysreg save/restore functions arch/arm64/kvm/hyp/sysreg-sr.c | 48 ++++++++++++++++++++++++++++++------------ 1 file changed, 35 insertions(+), 13 deletions(-) diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c index 99fc60516103..d5a5145b4e7c 100644 --- a/arch/arm64/kvm/hyp/sysreg-sr.c +++ b/arch/arm64/kvm/hyp/sysreg-sr.c @@ -28,24 +28,33 @@ static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { } /* * Non-VHE: Both host and guest must save everything. * - * VHE: Host must save tpidr*_el0, actlr_el1, mdscr_el1, sp_el0, + * VHE: Host must save tpidr*_el0, mdscr_el1, sp_el0, * and guest must save everything. */ static void __hyp_text __sysreg_save_common_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); + + /* + * 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_state(struct kvm_cpu_context *ctxt) +static void __hyp_text __sysreg_save_user_state(struct kvm_cpu_context *ctxt) +{ + ctxt->sys_regs[TPIDR_EL0] = read_sysreg(tpidr_el0); + ctxt->sys_regs[TPIDRRO_EL0] = read_sysreg(tpidrro_el0); +} + +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); ctxt->sys_regs[SCTLR_EL1] = read_sysreg_el1(sctlr); + ctxt->sys_regs[ACTLR_EL1] = read_sysreg(actlr_el1); ctxt->sys_regs[CPACR_EL1] = read_sysreg_el1(cpacr); ctxt->sys_regs[TTBR0_EL1] = read_sysreg_el1(ttbr0); ctxt->sys_regs[TTBR1_EL1] = read_sysreg_el1(ttbr1); @@ -73,35 +82,46 @@ 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[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); write_sysreg_el1(ctxt->sys_regs[SCTLR_EL1], sctlr); + write_sysreg(ctxt->sys_regs[ACTLR_EL1], actlr_el1); write_sysreg_el1(ctxt->sys_regs[CPACR_EL1], cpacr); write_sysreg_el1(ctxt->sys_regs[TTBR0_EL1], ttbr0); write_sysreg_el1(ctxt->sys_regs[TTBR1_EL1], ttbr1); @@ -129,19 +149,21 @@ 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); } void __hyp_text __sysreg32_save_state(struct kvm_vcpu *vcpu) -- 2.14.2 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm