Patchwork [v2,6/8] arm64: KVM: Add synchronization on translation regime change for erratum 1165522

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Submitter Marc Zyngier
Date Nov. 23, 2018, 6:41 p.m.
Message ID <20181123184107.39334-7-marc.zyngier@arm.com>
Download mbox | patch
Permalink /patch/664007/
State New
Headers show

Comments

Marc Zyngier - Nov. 23, 2018, 6:41 p.m.
In order to ensure that slipping HCR_EL2.TGE is done at the right
time when switching translation regime, let insert the required ISBs
that will be patched in when erratum 1165522 is detected.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/kvm_hyp.h |  7 +++++++
 arch/arm64/kvm/hyp/switch.c      | 19 +++++++++++++++++++
 2 files changed, 26 insertions(+)
James Morse - Nov. 27, 2018, 9:51 a.m.
Hi Marc,

On 23/11/2018 18:41, Marc Zyngier wrote:
> In order to ensure that slipping HCR_EL2.TGE is done at the right
> time when switching translation regime, let insert the required ISBs
> that will be patched in when erratum 1165522 is detected.

Reviewed-by: James Morse <james.morse@arm.com>


> diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
> index 23aca66767f9..ce46bb1c5f4b 100644
> --- a/arch/arm64/include/asm/kvm_hyp.h
> +++ b/arch/arm64/include/asm/kvm_hyp.h
> @@ -163,6 +163,13 @@ static __always_inline void __hyp_text __load_guest_stage2(struct kvm *kvm)
>  {
>  	write_sysreg(kvm->arch.vtcr, vtcr_el2);
>  	write_sysreg(kvm->arch.vttbr, vttbr_el2);
> +
> +	/*
> +	 * ARM erratum 1165522 requires the actual execution of the above
> +	 * before we can switch to the EL1/EL0 translation regime used by
> +	 * the guest.
> +	 */
> +	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_1165522));

(kvm_hyp.h doesn't include alternative.h, .... but already uses ALTERNATIVE())


Thanks,

James

Patch

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 23aca66767f9..ce46bb1c5f4b 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -163,6 +163,13 @@  static __always_inline void __hyp_text __load_guest_stage2(struct kvm *kvm)
 {
 	write_sysreg(kvm->arch.vtcr, vtcr_el2);
 	write_sysreg(kvm->arch.vttbr, vttbr_el2);
+
+	/*
+	 * ARM erratum 1165522 requires the actual execution of the above
+	 * before we can switch to the EL1/EL0 translation regime used by
+	 * the guest.
+	 */
+	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_1165522));
 }
 
 #endif /* __ARM64_KVM_HYP_H__ */
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index a8fa61c68c32..31ee0bfc432f 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -143,6 +143,14 @@  static void deactivate_traps_vhe(void)
 {
 	extern char vectors[];	/* kernel exception vectors */
 	write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);
+
+	/*
+	 * ARM erratum 1165522 requires the actual execution of the above
+	 * before we can switch to the EL2/EL0 translation regime used by
+	 * the host.
+	 */
+	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_1165522));
+
 	write_sysreg(CPACR_EL1_DEFAULT, cpacr_el1);
 	write_sysreg(vectors, vbar_el1);
 }
@@ -499,6 +507,17 @@  int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
 
 	sysreg_save_host_state_vhe(host_ctxt);
 
+	/*
+	 * ARM erratum 1165522 requires us to configure both stage 1 and
+	 * stage 2 translation for the guest context before we clear
+	 * HCR_EL2.TGE.
+	 *
+	 * We have already configured the guest's stage 1 translation in
+	 * kvm_vcpu_load_sysregs above.  We must now call __activate_vm
+	 * before __activate_traps, because __activate_vm configures
+	 * stage 2 translation, and __activate_traps clear HCR_EL2.TGE
+	 * (among other things).
+	 */
 	__activate_vm(vcpu->kvm);
 	__activate_traps(vcpu);