[PATCH v4 33/40] KVM: arm64: Configure c15, PMU, and debug register traps on cpu load/put for VHE
Marc Zyngier
marc.zyngier at arm.com
Wed Feb 21 10:20:54 PST 2018
On Thu, 15 Feb 2018 21:03:25 +0000,
Christoffer Dall wrote:
>
> We do not have to change the c15 trap setting on each switch to/from the
> guest on VHE systems, because this setting only affects EL0.
Did you mean EL1 instead?
>
> The PMU and debug trap configuration can also be done on vcpu load/put
> instead, because they don't affect how the host kernel can access the
> debug registers while executing KVM kernel code.
>
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
> ---
> arch/arm64/include/asm/kvm_hyp.h | 3 +++
> arch/arm64/kvm/hyp/switch.c | 31 ++++++++++++++++++++++---------
> arch/arm64/kvm/hyp/sysreg-sr.c | 4 ++++
> 3 files changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
> index 2b1fda90dde4..949f2e77ae58 100644
> --- a/arch/arm64/include/asm/kvm_hyp.h
> +++ b/arch/arm64/include/asm/kvm_hyp.h
> @@ -147,6 +147,9 @@ void __fpsimd_save_state(struct user_fpsimd_state *fp_regs);
> void __fpsimd_restore_state(struct user_fpsimd_state *fp_regs);
> bool __fpsimd_enabled(void);
>
> +void activate_traps_vhe_load(struct kvm_vcpu *vcpu);
> +void deactivate_traps_vhe_put(void);
> +
> u64 __guest_enter(struct kvm_vcpu *vcpu, struct kvm_cpu_context *host_ctxt);
> void __noreturn __hyp_do_panic(unsigned long, ...);
>
> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> index 9c40e203bd09..5e94955b89ea 100644
> --- a/arch/arm64/kvm/hyp/switch.c
> +++ b/arch/arm64/kvm/hyp/switch.c
> @@ -101,6 +101,8 @@ static void __hyp_text __activate_traps_nvhe(struct kvm_vcpu *vcpu)
> {
> u64 val;
>
> + __activate_traps_common(vcpu);
> +
> val = CPTR_EL2_DEFAULT;
> val |= CPTR_EL2_TTA | CPTR_EL2_TFP | CPTR_EL2_TZ;
> write_sysreg(val, cptr_el2);
> @@ -120,20 +122,12 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
> write_sysreg_s(vcpu->arch.vsesr_el2, SYS_VSESR_EL2);
>
> __activate_traps_fpsimd32(vcpu);
> - __activate_traps_common(vcpu);
> __activate_traps_arch()(vcpu);
> }
>
> static void __hyp_text __deactivate_traps_vhe(void)
> {
> extern char vectors[]; /* kernel exception vectors */
> - u64 mdcr_el2 = read_sysreg(mdcr_el2);
> -
> - mdcr_el2 &= MDCR_EL2_HPMN_MASK |
> - MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT |
> - MDCR_EL2_TPMS;
> -
> - write_sysreg(mdcr_el2, mdcr_el2);
> write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);
> write_sysreg(CPACR_EL1_DEFAULT, cpacr_el1);
> write_sysreg(vectors, vbar_el1);
> @@ -143,6 +137,8 @@ static void __hyp_text __deactivate_traps_nvhe(void)
> {
> u64 mdcr_el2 = read_sysreg(mdcr_el2);
>
> + __deactivate_traps_common();
> +
> mdcr_el2 &= MDCR_EL2_HPMN_MASK;
> mdcr_el2 |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT;
>
> @@ -166,10 +162,27 @@ static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
> if (vcpu->arch.hcr_el2 & HCR_VSE)
> vcpu->arch.hcr_el2 = read_sysreg(hcr_el2);
>
> - __deactivate_traps_common();
> __deactivate_traps_arch()();
> }
>
> +void activate_traps_vhe_load(struct kvm_vcpu *vcpu)
> +{
> + __activate_traps_common(vcpu);
> +}
> +
> +void deactivate_traps_vhe_put(void)
> +{
> + u64 mdcr_el2 = read_sysreg(mdcr_el2);
> +
> + mdcr_el2 &= MDCR_EL2_HPMN_MASK |
> + MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT |
> + MDCR_EL2_TPMS;
> +
> + write_sysreg(mdcr_el2, mdcr_el2);
> +
> + __deactivate_traps_common();
> +}
> +
> static void __hyp_text __activate_vm(struct kvm *kvm)
> {
> write_sysreg(kvm->arch.vttbr, vttbr_el2);
> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> index aacba4636871..b3894df6bf1a 100644
> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> @@ -254,6 +254,8 @@ void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu)
> __sysreg_restore_el1_state(guest_ctxt);
>
> vcpu->arch.sysregs_loaded_on_cpu = true;
> +
> + activate_traps_vhe_load(vcpu);
> }
>
> /**
> @@ -275,6 +277,8 @@ void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu)
> if (!has_vhe())
> return;
>
> + deactivate_traps_vhe_put();
> +
> __sysreg_save_el1_state(guest_ctxt);
> __sysreg_save_user_state(guest_ctxt);
> __sysreg32_save_state(vcpu);
> --
> 2.14.2
>
I must admit that I find these two layers of trap configuration mildly
confusing. I can see why it is done like this (there is hardly any
other way), but still...
Reviewed-by: Marc Zyngier <marc.zyngier at arm.com>
M.
--
Jazz is not dead, it just smell funny.
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