[RFC PATCH v1 27/30] KVM: arm64: remove unsupported pVM features

[Fuad Tabba]

Remove code for unsupported features for protected VMs from
__kvm_vcpu_run_pvm(). Do not run unsupported code (SVE) in
__hyp_handle_fpsimd().

Enforcement of this is in the fixed features patch series [1].
The code removed or disabled is related to the following:
- PMU
- Debug
- Arm32
- SPE
- SVE

[1]
Link: https://lore.kernel.org/kvmarm/20210922124704.600087-1-tabba@google.com/T/#u

Signed-off-by: Fuad Tabba <tabba at google.com>
---
 arch/arm64/kvm/hyp/include/hyp/switch.h |  5 ++--
 arch/arm64/kvm/hyp/nvhe/switch.c        | 36 -------------------------
 2 files changed, 3 insertions(+), 38 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 433601f79b94..3ef429cfd9af 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -232,6 +232,7 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_hyp_state *vcpu_hyps = &hyp_state(vcpu);
 	struct kvm_cpu_context *vcpu_ctxt = &vcpu_ctxt(vcpu);
+	const bool is_protected = is_nvhe_hyp_code() && kvm_vm_is_protected(kern_hyp_va(vcpu->kvm));
 	bool sve_guest, sve_host;
 	u8 esr_ec;
 	u64 reg;
@@ -239,7 +240,7 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
 	if (!system_supports_fpsimd())
 		return false;
 
-	if (system_supports_sve()) {
+	if (system_supports_sve() && !is_protected) {
 		sve_guest = hyp_state_has_sve(vcpu_hyps);
 		sve_host = hyp_state_flags(vcpu_hyps) & KVM_ARM64_HOST_SVE_IN_USE;
 	} else {
@@ -247,7 +248,7 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
 		sve_host = false;
 	}
 
-	esr_ec = kvm_vcpu_trap_get_class(vcpu);
+	esr_ec = kvm_hyp_state_trap_get_class(vcpu_hyps);
 	if (esr_ec != ESR_ELx_EC_FP_ASIMD &&
 	    esr_ec != ESR_ELx_EC_SVE)
 		return false;
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 0d654b324612..aa0dc4f0433b 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -288,7 +288,6 @@ static int __kvm_vcpu_run_pvm(struct kvm_vcpu *vcpu)
 	struct vgic_dist *vgic = &kvm->arch.vgic;
 	struct kvm_cpu_context *host_ctxt;
 	struct kvm_cpu_context *guest_ctxt;
-	bool pmu_switch_needed;
 	u64 exit_code;
 
 	/*
@@ -306,29 +305,10 @@ static int __kvm_vcpu_run_pvm(struct kvm_vcpu *vcpu)
 	set_hyp_running_vcpu(host_ctxt, vcpu);
 	guest_ctxt = &vcpu->arch.ctxt;
 
-	pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);
-
 	__sysreg_save_state_nvhe(host_ctxt);
-	/*
-	 * We must flush and disable the SPE buffer for nVHE, as
-	 * the translation regime(EL1&0) is going to be loaded with
-	 * that of the guest. And we must do this before we change the
-	 * translation regime to EL2 (via MDCR_EL2_E2PB == 0) and
-	 * before we load guest Stage1.
-	 */
-	__debug_save_host_buffers_nvhe(vcpu);
 
 	kvm_adjust_pc(vcpu_ctxt, vcpu_hyps);
 
-	/*
-	 * We must restore the 32-bit state before the sysregs, thanks
-	 * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
-	 *
-	 * Also, and in order to be able to deal with erratum #1319537 (A57)
-	 * and #1319367 (A72), we must ensure that all VM-related sysreg are
-	 * restored before we enable S2 translation.
-	 */
-	__sysreg32_restore_state(vcpu);
 	__sysreg_restore_state_nvhe(guest_ctxt);
 
 	__load_guest_stage2(kern_hyp_va(vcpu->arch.hw_mmu));
@@ -337,8 +317,6 @@ static int __kvm_vcpu_run_pvm(struct kvm_vcpu *vcpu)
 	__hyp_vgic_restore_state(vcpu);
 	__timer_enable_traps();
 
-	__debug_switch_to_guest(vcpu);
-
 	do {
 		struct kvm_cpu_context *hyp_ctxt = this_cpu_ptr(&kvm_hyp_ctxt);
 		set_hyp_running_vcpu(hyp_ctxt, vcpu);
@@ -350,7 +328,6 @@ static int __kvm_vcpu_run_pvm(struct kvm_vcpu *vcpu)
 	} while (fixup_guest_exit(vcpu, vgic, &exit_code));
 
 	__sysreg_save_state_nvhe(guest_ctxt);
-	__sysreg32_save_state(vcpu);
 	__timer_disable_traps();
 	__hyp_vgic_save_state(vcpu);
 
@@ -359,19 +336,6 @@ static int __kvm_vcpu_run_pvm(struct kvm_vcpu *vcpu)
 
 	__sysreg_restore_state_nvhe(host_ctxt);
 
-	if (hyp_state_flags(vcpu_hyps) & KVM_ARM64_FP_ENABLED)
-		__fpsimd_save_fpexc32(vcpu);
-
-	__debug_switch_to_host(vcpu);
-	/*
-	 * This must come after restoring the host sysregs, since a non-VHE
-	 * system may enable SPE here and make use of the TTBRs.
-	 */
-	__debug_restore_host_buffers_nvhe(vcpu);
-
-	if (pmu_switch_needed)
-		__pmu_switch_to_host(host_ctxt);
-
 	/* Returning to host will clear PSR.I, remask PMR if needed */
 	if (system_uses_irq_prio_masking())
 		gic_write_pmr(GIC_PRIO_IRQOFF);
-- 
2.33.0.685.g46640cef36-goog